- title: ECMAScript® 2025 Language Specification + title: ECMAScript® 2027 Language Specification shortname: ECMA-262 status: draft + committee: 39 location: https://tc39.es/ecma262/ markEffects: true + boilerplate: + copyright: alternative
About this Specification
-The document at https://tc39.es/ecma262/ is the most accurate and up-to-date ECMAScript specification. It contains the content of the most recent yearly snapshot plus any finished proposals (those that have reached Stage 4 in the proposal process and thus are implemented in several implementations and will be in the next practical revision) since that snapshot was taken.
+The document at https://tc39.es/ecma262/ is the most accurate and up-to-date ECMAScript specification. It contains the content of the most recent yearly snapshot plus any finished proposals — those that have reached Stage 4 in the proposal process and thus are implemented in several implementations and will be included in the next yearly snapshot. Historical snapshots are available at https://ecma-international.org/publications-and-standards/standards/ecma-262/.
This document is available as a single page and as multiple pages.
Contributing to this Specification
This specification is developed on GitHub with the help of the ECMAScript community. There are a number of ways to contribute to the development of this specification:
@@ -49,9 +138,12 @@Contributing to this Specification
Contributing to this Specification
Introduction
-This Ecma Standard defines the ECMAScript 2025 Language. It is the sixteenth edition of the ECMAScript Language Specification. Since publication of the first edition in 1997, ECMAScript has grown to be one of the world's most widely used general-purpose programming languages. It is best known as the language embedded in web browsers but has also been widely adopted for server and embedded applications.
-ECMAScript is based on several originating technologies, the most well-known being JavaScript (Netscape) and JScript (Microsoft). The language was invented by Brendan Eich at Netscape and first appeared in that company's Navigator 2.0 browser. It has appeared in all subsequent browsers from Netscape and in all browsers from Microsoft starting with Internet Explorer 3.0.
+This Ecma Standard defines the ECMAScript 2027 Language. It is the eighteenth edition of the ECMAScript Language Specification. ECMAScript is based on several originating technologies, the most well-known being JavaScript (Netscape) and JScript (Microsoft). The language was invented by Brendan Eich at Netscape and first appeared in that company's Navigator 2.0 browser. Though best known as the language embedded in web browsers, it has also been widely adopted for use outside the browser, including server and embedded applications, and has grown to be one of the world's most widely used general-purpose programming languages.
The development of the ECMAScript Language Specification started in November 1996. The first edition of this Ecma Standard was adopted by the Ecma General Assembly of June 1997.
That Ecma Standard was submitted to ISO/IEC JTC 1 for adoption under the fast-track procedure, and approved as international standard ISO/IEC 16262, in April 1998. The Ecma General Assembly of June 1998 approved the second edition of ECMA-262 to keep it fully aligned with ISO/IEC 16262. Changes between the first and the second edition are editorial in nature.
The third edition of the Standard introduced powerful regular expressions, better string handling, new control statements, try/catch exception handling, tighter definition of errors, formatting for numeric output and minor changes in anticipation of future language growth. The third edition of the ECMAScript standard was adopted by the Ecma General Assembly of December 1999 and published as ISO/IEC 16262:2002 in June 2002.
@@ -79,13 +170,15 @@Introduction
Focused development of the sixth edition started in 2009, as the fifth edition was being prepared for publication. However, this was preceded by significant experimentation and language enhancement design efforts dating to the publication of the third edition in 1999. In a very real sense, the completion of the sixth edition is the culmination of a fifteen year effort. The goals for this edition included providing better support for large applications, library creation, and for use of ECMAScript as a compilation target for other languages. Some of its major enhancements included modules, class declarations, lexical block scoping, iterators and generators, promises for asynchronous programming, destructuring patterns, and proper tail calls. The ECMAScript library of built-ins was expanded to support additional data abstractions including maps, sets, and arrays of binary numeric values as well as additional support for Unicode supplementary characters in strings and regular expressions. The built-ins were also made extensible via subclassing. The sixth edition provides the foundation for regular, incremental language and library enhancements. The sixth edition was adopted by the General Assembly of June 2015.
ECMAScript 2016 was the first ECMAScript edition released under Ecma TC39's new yearly release cadence and open development process. A plain-text source document was built from the ECMAScript 2015 source document to serve as the base for further development entirely on GitHub. Over the year of this standard's development, hundreds of pull requests and issues were filed representing thousands of bug fixes, editorial fixes and other improvements. Additionally, numerous software tools were developed to aid in this effort including Ecmarkup, Ecmarkdown, and Grammarkdown. ES2016 also included support for a new exponentiation operator and adds a new method to `Array.prototype` called `includes`.
ECMAScript 2017 introduced Async Functions, Shared Memory, and Atomics along with smaller language and library enhancements, bug fixes, and editorial updates. Async functions improve the asynchronous programming experience by providing syntax for promise-returning functions. Shared Memory and Atomics introduce a new memory model that allows multi-agent programs to communicate using atomic operations that ensure a well-defined execution order even on parallel CPUs. It also included new static methods on Object: `Object.values`, `Object.entries`, and `Object.getOwnPropertyDescriptors`.
-ECMAScript 2018 introduced support for asynchronous iteration via the AsyncIterator protocol and async generators. It also included four new regular expression features: the `dotAll` flag, named capture groups, Unicode property escapes, and look-behind assertions. Lastly it included object rest and spread properties.
+ECMAScript 2018 introduced support for asynchronous iteration via the async iterator protocol and async generators. It also included four new regular expression features: the `dotAll` flag, named capture groups, Unicode property escapes, and look-behind assertions. Lastly it included object rest and spread properties.
ECMAScript 2019 introduced a few new built-in functions: `flat` and `flatMap` on `Array.prototype` for flattening arrays, `Object.fromEntries` for directly turning the return value of `Object.entries` into a new Object, and `trimStart` and `trimEnd` on `String.prototype` as better-named alternatives to the widely implemented but non-standard `String.prototype.trimLeft` and `trimRight` built-ins. In addition, it included a few minor updates to syntax and semantics. Updated syntax included optional catch binding parameters and allowing U+2028 (LINE SEPARATOR) and U+2029 (PARAGRAPH SEPARATOR) in string literals to align with JSON. Other updates included requiring that `Array.prototype.sort` be a stable sort, requiring that `JSON.stringify` return well-formed UTF-8 regardless of input, and clarifying `Function.prototype.toString` by requiring that it either return the corresponding original source text or a standard placeholder.
ECMAScript 2020, the 11th edition, introduced the `matchAll` method for Strings, to produce an iterator for all match objects generated by a global regular expression; `import()`, a syntax to asynchronously import Modules with a dynamic specifier; `BigInt`, a new number primitive for working with arbitrary precision integers; `Promise.allSettled`, a new Promise combinator that does not short-circuit; `globalThis`, a universal way to access the global `this` value; dedicated `export * as ns from 'module'` syntax for use within modules; increased standardization of `for-in` enumeration order; `import.meta`, a host-populated object available in Modules that may contain contextual information about the Module; as well as adding two new syntax features to improve working with “nullish” values (*undefined* or *null*): nullish coalescing, a value selection operator; and optional chaining, a property access and function invocation operator that short-circuits if the value to access/invoke is nullish.
ECMAScript 2021, the 12th edition, introduced the `replaceAll` method for Strings; `Promise.any`, a Promise combinator that short-circuits when an input value is fulfilled; `AggregateError`, a new Error type to represent multiple errors at once; logical assignment operators (`??=`, `&&=`, `||=`); `WeakRef`, for referring to a target object without preserving it from garbage collection, and `FinalizationRegistry`, to manage registration and unregistration of cleanup operations performed when target objects are garbage collected; separators for numeric literals (`1_000`); and `Array.prototype.sort` was made more precise, reducing the amount of cases that result in an implementation-defined sort order.
ECMAScript 2022, the 13th edition, introduced top-level `await`, allowing the keyword to be used at the top level of modules; new class elements: public and private instance fields, public and private static fields, private instance methods and accessors, and private static methods and accessors; static blocks inside classes, to perform per-class evaluation initialization; the `#x in obj` syntax, to test for presence of private fields on objects; regular expression match indices via the `/d` flag, which provides start and end indices for matched substrings; the `cause` property on `Error` objects, which can be used to record a causation chain in errors; the `at` method for Strings, Arrays, and TypedArrays, which allows relative indexing; and `Object.hasOwn`, a convenient alternative to `Object.prototype.hasOwnProperty`.
ECMAScript 2023, the 14th edition, introduced the `toSorted`, `toReversed`, `with`, `findLast`, and `findLastIndex` methods on `Array.prototype` and `TypedArray.prototype`, as well as the `toSpliced` method on `Array.prototype`; added support for `#!` comments at the beginning of files to better facilitate executable ECMAScript files; and allowed the use of most Symbols as keys in weak collections.
ECMAScript 2024, the 15th edition, added facilities for resizing and transferring ArrayBuffers and SharedArrayBuffers; added a new RegExp `/v` flag for creating RegExps with more advanced features for working with sets of strings; and introduced the `Promise.withResolvers` convenience method for constructing Promises, the `Object.groupBy` and `Map.groupBy` methods for aggregating data, the `Atomics.waitAsync` method for asynchronously waiting for a change to shared memory, and the `String.prototype.isWellFormed` and `String.prototype.toWellFormed` methods for checking and ensuring that strings contain only well-formed Unicode.
+ECMAScript 2025, the 16th edition, added a new `Iterator` global with associated static and prototype methods for working with iterators; added methods to `Set.prototype` for performing common operations on Sets; added support for importing JSON modules as well as syntax for declaring attributes of imported modules; added the `RegExp.escape` method for escaping a string to be safely used in a regular expression; added syntax for enabling and disabling modifier flags inline within regular expressions; added the `Promise.try` method for calling functions which may or may not return a `Promise` and ensuring the result is always a `Promise`; and added a new `Float16Array` TypedArray kind as well as the related `DataView.prototype.getFloat16`, `DataView.prototype.setFloat16`, and `Math.f16round` methods.
+ECMAScript 2026, the 17th edition, added `Math.sumPrecise` for summing an iterable of Numbers of varying magnitude while minimizing precision loss; `Iterator.concat` for sequencing iterators; `Array.fromAsync` for constructing Arrays from async iterables and other async sources; `Error.isError` for identifying error objects; methods to `Map.prototype` and `WeakMap.prototype` for providing a default value to use during retrieval when a key is not already present; methods to `Uint8Array` for converting to and from Strings of hexadecimal- and base64-encoded binary data; a parameter to `JSON.parse` revivers to access the matched segment of JSON source; and `JSON.rawJSON` for fine control over `JSON.stringify` output for primitive values.
Dozens of individuals representing many organizations have made very significant contributions within Ecma TC39 to the development of this edition and to the prior editions. In addition, a vibrant community has emerged supporting TC39's ECMAScript efforts. This community has reviewed numerous drafts, filed thousands of bug reports, performed implementation experiments, contributed test suites, and educated the world-wide developer community about ECMAScript. Unfortunately, it is impossible to identify and acknowledge every person and organization who has contributed to this effort.
Allen Wirfs-Brock
@@ -99,23 +192,39 @@
Introduction
Jordan HarbandECMA-262, Project Editor, 10th through 12th Editions +
+ Kevin Gibbons
+ ECMA-262, Project Editor, 12th through 17th Editions
+
Shu-yu Guo
- ECMA-262, Project Editor, 12th through 15th Editions
+ ECMA-262, Project Editor, 12th through 18th Editions
Michael Ficarra
- ECMA-262, Project Editor, 12th through 15th Editions
+ ECMA-262, Project Editor, 12th through 18th Editions
- Kevin Gibbons
- ECMA-262, Project Editor, 12th through 15th Editions
+ Richard Gibson
+ ECMA-262, Project Editor, 18th Edition
+
+ Ron Buckton
+ ECMA-262, Project Editor, 18th Edition
+
+ Nicolò Ribaudo
+ ECMA-262, Project Editor, 18th Edition
+
+ Linus Groh
+ ECMA-262, Project Editor, 18th Edition
Scope
-This Standard defines the ECMAScript 2025 general-purpose programming language.
+This Standard defines the ECMAScript 2027 general-purpose programming language.
Conformance
A conforming implementation of ECMAScript may support program and regular expression syntax not described in this specification. In particular, a conforming implementation of ECMAScript may support program syntax that makes use of any “future reserved words” noted in subclause
A conforming implementation of ECMAScript must not implement any extension that is listed as a Forbidden Extension in subclause
A conforming implementation of ECMAScript must not redefine any facilities that are not implementation-defined, implementation-approximated, or host-defined.
-A conforming implementation of ECMAScript may choose to implement or not implement Normative Optional subclauses. If any Normative Optional behaviour is implemented, all of the behaviour in the containing Normative Optional clause must be implemented. A Normative Optional clause is denoted in this specification with the words "Normative Optional" in a coloured box, as shown below.
+A conforming implementation of ECMAScript may choose to implement or not implement Normative Optional subclauses, unless otherwise indicated. Web browsers are generally required to implement all normative optional subclauses. (See Annex
Example Normative Optional Clause Heading
@@ -386,7 +495,7 @@Number value
Number type
-set of all possible Number values including the special “Not-a-Number” (NaN) value, positive infinity, and negative infinity
+set of all possible Number values including *NaN* (“not a number”), *+∞*𝔽 (positive infinity), and *-∞*𝔽 (negative infinity)
Infinity
NaN
-Number value that is an IEEE 754-2019 “Not-a-Number” value
+Number value that is an IEEE 754-2019 NaN (“not a number”) value
The Syntactic Grammar
Productions of the syntactic grammar are distinguished by having just one colon “:” as punctuation.
The syntactic grammar as presented in clauses
In certain cases, in order to avoid ambiguities, the syntactic grammar uses generalized productions that permit token sequences that do not form a valid ECMAScript |Script| or |Module|. For example, this technique is used for object literals and object destructuring patterns. In such cases a more restrictive supplemental grammar is provided that further restricts the acceptable token sequences. Typically, an early error rule will then state that, in certain contexts, "_P_ must cover an _N_", where _P_ is a Parse Node (an instance of the generalized production) and _N_ is a nonterminal from the supplemental grammar. This means:
+In certain cases, in order to avoid ambiguities, the syntactic grammar uses generalized productions that permit token sequences that do not form a valid ECMAScript |Script| or |Module|. For example, this technique is used for object literals and object destructuring patterns. In such cases a more restrictive supplemental grammar is provided that further restricts the acceptable token sequences. Typically, an early error rule will then state that, in certain contexts, “_p_ must cover an _n_”, where _p_ is a Parse Node (an instance of the generalized production) and _n_ is a nonterminal from the supplemental grammar. This means:
-
-
- The sequence of tokens originally matched by _P_ is parsed again using _N_ as the goal symbol. If _N_ takes grammatical parameters, then they are set to the same values used when _P_ was originally parsed. -
- If the sequence of tokens can be parsed as a single instance of _N_, with no tokens left over, then: +
- No early error rules are applied to _p_ or any of its descendants. +
- The sequence of tokens originally matched by _p_ is parsed again using _n_ as the goal symbol. If _n_ takes grammatical parameters, then they are set to the same values used when _p_ was originally parsed. +
- If the sequence of tokens can be parsed as a single instance of _n_, with no tokens left over, then:
-
-
- We refer to that instance of _N_ (a Parse Node, unique for a given _P_) as "the _N_ that is covered by _P_". -
- All Early Error rules for _N_ and its derived productions also apply to the _N_ that is covered by _P_. +
- We refer to that instance of _n_ (a Parse Node, unique for a given _p_) as “the _n_ that is covered by _p_”. +
- Early error rules are applied to the _n_ that is covered by _p_ and to its descendants, as modified by further cases of "must cover".
- Otherwise (if the parse fails), it is an early Syntax Error. @@ -588,7 +698,7 @@
- In the lexical and RegExp grammars, Unicode code points without a conventional printed representation are instead shown in the form "<ABBREV>" where "ABBREV" is a mnemonic for the code point or set of code points. These forms are defined in
, , and .
+ - In the lexical and RegExp grammars, Unicode code points without a conventional printed representation are instead shown in the form “<ABBREV>” where “ABBREV” is a mnemonic for the code point or set of code points. These forms are defined in
, , and . - In the syntactic grammar, certain terminal symbols (e.g. |IdentifierName| and |RegularExpressionLiteral|) are shown in italics, as they refer to the nonterminals of the same name in the lexical grammar.
Terminal Symbols
In contrast, in the syntactic grammar, a contiguous run of fixed-width code points is a single terminal symbol.
Terminal symbols come in two other forms:
-
-
Grammatical Parameters
ReturnStatement ExpressionStatement -Multiple parameters produce a combinatory number of productions, not all of which are necessarily referenced in a complete grammar.
+Multiple parameters produce a combinatoric number of productions, not all of which are necessarily referenced in a complete grammar.
References to nonterminals on the right-hand side of a production can also be parameterized. For example:
Algorithm Conventions
1. SubsubsubsubsubstepA step or substep may be written as an “if” predicate that conditions its substeps. In this case, the substeps are only applied if the predicate is true. If a step or substep begins with the word “else”, it is a predicate that is the negation of the preceding “if” predicate step at the same level.
-A step may specify the iterative application of its substeps.
-A step that begins with “Assert:” asserts an invariant condition of its algorithm. Such assertions are used to make explicit algorithmic invariants that would otherwise be implicit. Such assertions add no additional semantic requirements and hence need not be checked by an implementation. They are used simply to clarify algorithms.
+A step may begin with “For each” or “Repeat” to specify the iterative application of its substeps.
+A step that begins with “Assert:” asserts an invariant condition of its algorithm. Such assertions are used to make explicit algorithmic invariants that would otherwise be implicit. Similarly, a step that begins with “NOTE:” provides pertinent context for nearby steps. Assertion steps and note steps are strictly informative; they add no additional semantic requirements and hence need not be checked by an implementation.
Algorithm steps may declare named aliases for any value using the form “Let _x_ be _someValue_”. These aliases are reference-like in that both _x_ and _someValue_ refer to the same underlying data and modifications to either are visible to both. Algorithm steps that want to avoid this reference-like behaviour should explicitly make a copy of the right-hand side: “Let _x_ be a copy of _someValue_” creates a shallow copy of _someValue_.
Once declared, an alias may be referenced in any subsequent steps and must not be referenced from steps prior to the alias's declaration. Aliases may be modified using the form “Set _x_ to _someOtherValue_”.
+Evaluation Order
+When complex expressions appear in algorithm steps, these are to be understood as being evaluated in a left-to-right, inside-to-outside order. For example, the step
+is equivalent to
+where the various _tmpN_ aliases are ephemeral and visible only in these steps.
+Abstract Operations
In order to facilitate their use in multiple parts of this specification, some algorithms, called abstract operations, are named and written in parameterized functional form so that they may be referenced by name from within other algorithms. Abstract operations are typically referenced using a functional application style such as OperationName(_arg1_, _arg2_). Some abstract operations are treated as polymorphically dispatched methods of class-like specification abstractions. Such method-like abstract operations are typically referenced using a method application style such as _someValue_.OperationName(_arg1_, _arg2_).
@@ -911,6 +1040,8 @@
- description
- It is used to emphasize that a Completion Record is being returned.
+ - skip return checks
+ - true
1. Assert: _completionRecord_ is a Completion Record.
@@ -919,85 +1050,63 @@
Throw an Exception
-Algorithms steps that say to throw an exception, such as
+Throw
+In algorithm steps, the word “throw” is shorthand for returning the result of calling ThrowCompletion. For example,
mean the same things as:
+is equivalent to
ReturnIfAbrupt
-Algorithms steps that say or are otherwise equivalent to:
+Algorithm steps that say to throw an exception of a particular type construct an exception of that type to be thrown. For example,
mean the same thing as:
-Algorithms steps that say or are otherwise equivalent to:
-mean the same thing as:
-Where _hygienicTemp_ is ephemeral and visible only in the steps pertaining to ReturnIfAbrupt.
-Algorithms steps that say or are otherwise equivalent to:
-mean the same thing as:
+is equivalent to
ReturnIfAbrupt Shorthands
-Invocations of abstract operations and syntax-directed operations that are prefixed by `?` indicate that ReturnIfAbrupt should be applied to the resulting Completion Record. For example, the step:
+Shorthands for Unwrapping Completion Records
+Prefix “?” and “!” are used as shorthands which unwrap Completion Records. “?” is used to propagate an abrupt completion to the caller, or otherwise to unwrap a normal completion. “!” is used to assert that a Completion Record is normal and unwrap it. Formally, the step
is equivalent to the following step:
+is equivalent to
Similarly, for method application style, the step:
+Likewise, the step
is equivalent to:
+is equivalent to
Similarly, prefix `!` is used to indicate that the following invocation of an abstract or syntax-directed operation will never return an abrupt completion and that the resulting Completion Record's [[Value]] field should be used in place of the return value of the operation. For example, the step:
+When “?” or “!” is used in any other context, first apply the rewrite given in
is equivalent to the following steps:
+can be rewritten to
Syntax-directed operations for runtime semantics make use of this shorthand by placing `!` or `?` before the invocation of the operation:
+which in turn expands to
ReturnIfAbrupt Shorthands
Implicit Normal Completion
In algorithms within abstract operations which are declared to return a Completion Record, and within all built-in functions, the returned value is first passed to NormalCompletion, and the result is used instead. This rule does not apply within the Completion algorithm or when the value being returned is clearly marked as a Completion Record in that step; these cases are:
-
-
- when the result of applying Completion, NormalCompletion, or ThrowCompletion is directly returned +
- when the result of applying Completion, NormalCompletion, ThrowCompletion, or ReturnCompletion is directly returned
- when the result of constructing a Completion Record is directly returned
It is an editorial error if a Completion Record is returned from such an abstract operation through any other means. For example, within these abstract operations,
@@ -1025,7 +1134,7 @@Implicit Normal Completion
Note that, through the ReturnIfAbrupt expansion, the following example is allowed, as within the expanded steps, the result of applying Completion is returned directly in the abrupt case and the implicit NormalCompletion application occurs after unwrapping in the normal case.
+Note that, through
Mathematical Operations
In the language of this specification, numerical values are distinguished among different numeric kinds using subscript suffixes. The subscript 𝔽 refers to Numbers, and the subscript ℤ refers to BigInts. Numeric values without a subscript suffix refer to mathematical values. This specification denotes most numeric values in base 10; it also uses numeric values of the form 0x followed by digits 0-9 or A-F as base-16 values.
-In general, when this specification refers to a numerical value, such as in the phrase, "the length of _y_" or "the integer represented by the four hexadecimal digits ...", without explicitly specifying a numeric kind, the phrase refers to a mathematical value. Phrases which refer to a Number or a BigInt value are explicitly annotated as such; for example, "the Number value for the number of code points in …" or "the BigInt value for …".
-When the term integer is used in this specification, it refers to a mathematical value which is in the set of integers, unless otherwise stated. When the term integral Number is used in this specification, it refers to a Number value whose mathematical value is in the set of integers.
+In general, when this specification refers to a numerical value, such as in the phrase, “the length of _y_” or “the integer represented by the four hexadecimal digits ...”, without explicitly specifying a numeric kind, the phrase refers to a mathematical value. Phrases which refer to a Number or a BigInt value are explicitly annotated as such; for example, “the Number value for the number of code points in …” or “the BigInt value for …”.
+When the term integer is used in this specification, it refers to a mathematical value which is in the set of integers, unless otherwise stated. When the term integral Number is used in this specification, it refers to a finite Number value whose mathematical value is in the set of integers.
Numeric operators such as +, ×, =, and ≥ refer to those operations as determined by the type of the operands. When applied to mathematical values, the operators refer to the usual mathematical operations. When applied to extended mathematical values, the operators refer to the usual mathematical operations over the extended real numbers; indeterminate forms are not defined and their use in this specification should be considered an editorial error. When applied to Numbers, the operators refer to the relevant operations within IEEE 754-2019. When applied to BigInts, the operators refer to the usual mathematical operations applied to the mathematical value of the BigInt. Numeric operators applied to mixed-type operands (such as a Number and a mathematical value) are not defined and should be considered an editorial error in this specification.
-Conversions between mathematical values and Numbers or BigInts are always explicit in this document. A conversion from a mathematical value or extended mathematical value _x_ to a Number is denoted as "the Number value for _x_" or
Conversions between mathematical values and Numbers or BigInts are always explicit in this document. A conversion from a mathematical value or extended mathematical value _x_ to a Number is denoted as “the Number value for _x_” or
The mathematical function
The mathematical function
The mathematical function
The notation “
The phrase "the result of clamping _x_ between _lower_ and _upper_" (where _x_ is an extended mathematical value and _lower_ and _upper_ are mathematical values such that _lower_ ≤ _upper_) produces _lower_ if _x_ < _lower_, produces _upper_ if _x_ > _upper_, and otherwise produces _x_.
+The phrase “the result of clamping _x_ between _lower_ and _upper_” (where _x_ is an extended mathematical value and _lower_ and _upper_ are mathematical values such that _lower_ ≤ _upper_) produces _lower_ if _x_ < _lower_, produces _upper_ if _x_ > _upper_, and otherwise produces _x_.
The mathematical function
Value Notation
Identity
In this specification, both specification values and ECMAScript language values are compared for equality. When comparing for equality, values fall into one of two categories. Values without identity are equal to other values without identity if all of their innate characteristics are the same — characteristics such as the magnitude of an integer or the length of a sequence. Values without identity may be manifest without prior reference by fully describing their characteristics. In contrast, each value with identity is unique and therefore only equal to itself. Values with identity are like values without identity but with an additional unguessable, unchangeable, universally-unique characteristic called identity. References to existing values with identity cannot be manifest simply by describing them, as the identity itself is indescribable; instead, references to these values must be explicitly passed from one place to another. Some values with identity are mutable and therefore can have their characteristics (except their identity) changed in-place, causing all holders of the value to observe the new characteristics. A value without identity is never equal to a value with identity.
-From the perspective of this specification, the word “is” is used to compare two values for equality, as in “If _bool_ is *true*, then ...”, and the word “contains” is used to search for a value inside lists using equality comparisons, as in "If _list_ contains a Record _r_ such that _r_.[[Foo]] is *true*, then ...". The specification identity of values determines the result of these comparisons and is axiomatic in this specification.
+From the perspective of this specification, the word “is” is used to compare two values for equality, as in “If _bool_ is *true*, then ...”, and the word “contains” is used to search for a value inside lists using equality comparisons, as in “If _list_ contains a Record _r_ such that _r_.[[Foo]] is *true*, then ...”. The specification identity of values determines the result of these comparisons and is axiomatic in this specification.
From the perspective of the ECMAScript language, language values are compared for equality using the SameValue abstract operation and the abstract operations it transitively calls. The algorithms of these comparison abstract operations determine language identity of ECMAScript language values.
For specification values, examples of values without specification identity include, but are not limited to: mathematical values and extended mathematical values; ECMAScript source text, surrogate pairs, Directive Prologues, etc; UTF-16 code units; Unicode code points; enums; abstract operations, including syntax-directed operations, host hooks, etc; and ordered pairs. Examples of specification values with specification identity include, but are not limited to: any kind of Records, including Property Descriptors, PrivateElements, etc; Parse Nodes; Lists;
Specification identity agrees with language identity for all ECMAScript language values except Symbol values produced by
Identity
ECMAScript Data Types and Values
-Algorithms within this specification manipulate values each of which has an associated type. The possible value types are exactly those defined in this clause. Types are further subclassified into ECMAScript language types and specification types.
-Within this specification, the notation “Type(_x_)” is used as shorthand for “the type of _x_” where “type” refers to the ECMAScript language and specification types defined in this clause.
+Algorithms within this specification manipulate values each of which has an associated type. The possible value types are exactly those defined in this clause. Types are further classified into ECMAScript language types and specification types.
ECMAScript Language Types
@@ -1138,10 +1247,10 @@The String Type
The rationale behind this design was to keep the implementation of Strings as simple and high-performing as possible. If ECMAScript source text is in Normalized Form C, string literals are guaranteed to also be normalized, as long as they do not contain any Unicode escape sequences.
In this specification, the phrase "the string-concatenation of _A_, _B_, ..." (where each argument is a String value, a code unit, or a sequence of code units) denotes the String value whose sequence of code units is the concatenation of the code units (in order) of each of the arguments (in order).
-The phrase "the substring of _S_ from _inclusiveStart_ to _exclusiveEnd_" (where _S_ is a String value or a sequence of code units and _inclusiveStart_ and _exclusiveEnd_ are integers) denotes the String value consisting of the consecutive code units of _S_ beginning at index _inclusiveStart_ and ending immediately before index _exclusiveEnd_ (which is the empty String when _inclusiveStart_ = _exclusiveEnd_). If the "to" suffix is omitted, the length of _S_ is used as the value of _exclusiveEnd_.
+In this specification, the phrase “the string-concatenation of _A_, _B_, ...” (where each argument is a String value, a code unit, or a sequence of code units) denotes the String value whose sequence of code units is the concatenation of the code units (in order) of each of the arguments (in order).
+The phrase “the substring of _string_ from _inclusiveStart_ to _exclusiveEnd_” (where _string_ is a String value or a sequence of code units and _inclusiveStart_ and _exclusiveEnd_ are integers) denotes the String value consisting of the consecutive code units of _string_ beginning at index _inclusiveStart_ and ending immediately before index _exclusiveEnd_ (which is the empty String when _inclusiveStart_ = _exclusiveEnd_). If the "to" suffix is omitted, the length of _string_ is used as the value of _exclusiveEnd_.
- The phrase "the ASCII word characters" denotes the following String value, which consists solely of every letter and number in the Unicode Basic Latin block along with U+005F (LOW LINE):
+ The phrase “the ASCII word characters” denotes the following String value, which consists solely of every letter and number in the Unicode Basic Latin block along with U+005F (LOW LINE):
*"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_"*.
For historical reasons, it has significance to various algorithms.
- 1. Let _len_ be the length of _string_.
- 1. If _searchValue_ is the empty String and _fromIndex_ ≤ _len_, return _fromIndex_.
- 1. Let _searchLen_ be the length of _searchValue_.
- 1. For each integer _i_ such that _fromIndex_ ≤ _i_ ≤ _len_ - _searchLen_, in ascending order, do
- 1. Let _candidate_ be the substring of _string_ from _i_ to _i_ + _searchLen_.
+ 1. Let _length_ be the length of _string_.
+ 1. If _searchValue_ is the empty String and _fromIndex_ ≤ _length_, return _fromIndex_.
+ 1. Let _searchLength_ be the length of _searchValue_.
+ 1. For each integer _i_ such that _fromIndex_ ≤ _i_ ≤ _length_ - _searchLength_, in ascending order, do
+ 1. Let _candidate_ be the substring of _string_ from _i_ to _i_ + _searchLength_.
1. If _candidate_ is _searchValue_, return _i_.
1. Return ~not-found~.
@@ -1184,11 +1293,11 @@
- 1. Let _len_ be the length of _string_.
- 1. Let _searchLen_ be the length of _searchValue_.
- 1. Assert: _fromIndex_ + _searchLen_ ≤ _len_.
+ 1. Let _length_ be the length of _string_.
+ 1. Let _searchLength_ be the length of _searchValue_.
+ 1. Assert: _fromIndex_ + _searchLength_ ≤ _length_.
1. For each integer _i_ such that 0 ≤ _i_ ≤ _fromIndex_, in descending order, do
- 1. Let _candidate_ be the substring of _string_ from _i_ to _i_ + _searchLen_.
+ 1. Let _candidate_ be the substring of _string_ from _i_ to _i_ + _searchLength_.
1. If _candidate_ is _searchValue_, return _i_.
1. Return ~not-found~.
@@ -1201,40 +1310,65 @@
The Symbol Type
The Symbol type is the set of all non-String values that may be used as the key of an Object property (
- Each possible Symbol value is unique and immutable.
- Each Symbol value immutably holds an associated value called [[Description]] that is either *undefined* or a String value.
+ Each Symbol is unique and immutable.
+ Each Symbol has an immutable [[Description]] internal slot whose value is either a String or *undefined*.
Well-Known Symbols
Well-known symbols are built-in Symbol values that are explicitly referenced by algorithms of this specification. They are typically used as the keys of properties whose values serve as extension points of a specification algorithm. Unless otherwise specified, well-known symbols values are shared by all realms (
- Within this specification a well-known symbol is referred to by using a notation of the form @@name, where “name” is one of the values listed in
+ Within this specification a well-known symbol is referred to using the standard intrinsic notation where the intrinsic is one of the values listed in
+ Previous editions of this specification used a notation of the form @@name, where the current edition would use `%Symbol.name%`. In particular, the following names were used: @@asyncIterator, @@hasInstance, @@isConcatSpreadable, @@iterator , @@match, @@matchAll, @@replace, @@search, @@species, @@split, @@toPrimitive, @@toStringTag, and @@unscopables.
+
+
+
+ Specification Name
+
+
+ [[Description]]
+
+
+ Value and Purpose
+
+
+
-
- Specification Name
-
-
- [[Description]]
-
-
- Value and Purpose
-
+
+ %Symbol.asyncDispose%
+
+
+ *"Symbol.asyncDispose"*
+
+
+ A method that asynchronously performs resource cleanup on an object. Called by AsyncDisposableStack objects and `await using` declarations when evaluation of their containing scope completes.
+
- @@asyncIterator
+ %Symbol.asyncIterator%
*"Symbol.asyncIterator"*
- A method that returns the default AsyncIterator for an object. Called by the semantics of the `for`-`await`-`of` statement.
+ A method that returns the default async iterator for an object. Called by the semantics of the `for`-`await`-`of` statement.
- @@hasInstance
+ %Symbol.dispose%
+
+
+ *"Symbol.dispose"*
+
+
+ A method that performs explicit resource cleanup on an object. Called by DisposableStack objects, AsyncDisposableStack objects, and `using` declarations when evaluation of their containing scope completes.
+
+
+
+
+ %Symbol.hasInstance%
*"Symbol.hasInstance"*
@@ -1245,7 +1379,7 @@ Well-Known Symbols
- @@isConcatSpreadable
+ %Symbol.isConcatSpreadable%
*"Symbol.isConcatSpreadable"*
@@ -1256,18 +1390,18 @@ Well-Known Symbols
- @@iterator
+ %Symbol.iterator%
*"Symbol.iterator"*
- A method that returns the default Iterator for an object. Called by the semantics of the for-of statement.
+ A method that returns the default iterator for an object. Called by the semantics of the for-of statement.
- @@match
+ %Symbol.match%
*"Symbol.match"*
@@ -1278,18 +1412,18 @@ Well-Known Symbols
- @@matchAll
+ %Symbol.matchAll%
*"Symbol.matchAll"*
- A regular expression method that returns an iterator, that yields matches of the regular expression against a string. Called by the `String.prototype.matchAll` method.
+ A regular expression method that returns an iterator that yields matches of the regular expression against a string. Called by the `String.prototype.matchAll` method.
- @@replace
+ %Symbol.replace%
*"Symbol.replace"*
@@ -1300,7 +1434,7 @@ Well-Known Symbols
- @@search
+ %Symbol.search%
*"Symbol.search"*
@@ -1311,7 +1445,7 @@ Well-Known Symbols
- @@species
+ %Symbol.species%
*"Symbol.species"*
@@ -1322,7 +1456,7 @@ Well-Known Symbols
- @@split
+ %Symbol.split%
*"Symbol.split"*
@@ -1333,7 +1467,7 @@ Well-Known Symbols
- @@toPrimitive
+ %Symbol.toPrimitive%
*"Symbol.toPrimitive"*
@@ -1344,7 +1478,7 @@ Well-Known Symbols
- @@toStringTag
+ %Symbol.toStringTag%
*"Symbol.toStringTag"*
@@ -1355,7 +1489,7 @@ Well-Known Symbols
- @@unscopables
+ %Symbol.unscopables%
*"Symbol.unscopables"*
@@ -1371,23 +1505,25 @@ Well-Known Symbols
Numeric Types
- ECMAScript has two built-in numeric types: Number and BigInt. The following abstract operations are defined over these numeric types. The "Result" column shows the return type, along with an indication if it is possible for some invocations of the operation to return an abrupt completion.
+ ECMAScript has two built-in numeric types: Number and BigInt. The following abstract operations are defined over these numeric types. The “Result” column shows the return type, along with an indication if it is possible for some invocations of the operation to return an abrupt completion.
-
-
- Operation
-
-
- Example source
-
-
- Invoked by the Evaluation semantics of ...
-
-
- Result
-
-
+
+
+
+ Operation
+
+
+ Example source
+
+
+ Invoked by the Evaluation semantics of ...
+
+
+ Result
+
+
+
@@ -1728,9 +1864,8 @@ Numeric Types
`[x].includes(y)`
- Array, Map, and Set methods,
via
Boolean
@@ -1828,7 +1963,7 @@ Numeric Types
The Number Type
- The Number type has exactly 18,437,736,874,454,810,627 (that is, 264 - 253 + 3 ) values, representing the double-precision floating point IEEE 754-2019 binary64 values as specified in the IEEE Standard for Binary Floating-Point Arithmetic, except that the 9,007,199,254,740,990 (that is, 253 - 2 ) distinct “Not-a-Number” values of the IEEE Standard are represented in ECMAScript as a single special *NaN* value. (Note that the *NaN* value is produced by the program expression `NaN`.) In some implementations, external code might be able to detect a difference between various Not-a-Number values, but such behaviour is implementation-defined; to ECMAScript code, all *NaN* values are indistinguishable from each other.
+ The Number type has exactly 18,437,736,874,454,810,627 (that is, 264 - 253 + 3 ) values, representing the double-precision floating point IEEE 754-2019 binary64 values as specified in the IEEE Standard for Binary Floating-Point Arithmetic, except that the 9,007,199,254,740,990 (that is, 253 - 2 ) distinct NaN values of the IEEE Standard are represented in ECMAScript as a single special *NaN* value. (Note that the *NaN* value is produced by the program expression `NaN`.) In some implementations, external code might be able to detect a difference between various NaN values, but such behaviour is implementation-defined; to ECMAScript code, all *NaN* values are indistinguishable from each other.
The bit pattern that might be observed in an ArrayBuffer (see
@@ -1855,28 +1990,28 @@ The Number Type
Number::unaryMinus (
- _x_: a Number,
+ _number_: a Number,
): a Number
- 1. If _x_ is *NaN*, return *NaN*.
- 1. Return the result of negating _x_; that is, compute a Number with the same magnitude but opposite sign.
+ 1. If _number_ is *NaN*, return *NaN*.
+ 1. Return the negation of _number_; that is, compute a Number with the same magnitude but opposite sign.
Number::bitwiseNOT (
- _x_: a Number,
+ _number_: a Number,
): an integral Number
- 1. Let _oldValue_ be ! ToInt32(_x_).
- 1. Return the result of applying bitwise complement to _oldValue_. The mathematical value of the result is exactly representable as a 32-bit two's complement bit string.
+ 1. Let _oldValue_ be ! ToInt32(_number_).
+ 1. Return the bitwise complement of _oldValue_. The mathematical value of the result is exactly representable as a 32-bit two's complement bit string.
@@ -1896,28 +2031,32 @@
1. If _exponent_ is either *+0*𝔽 or *-0*𝔽, return *1*𝔽.
1. If _base_ is *NaN*, return *NaN*.
1. If _base_ is *+∞*𝔽, then
- 1. If _exponent_ > *+0*𝔽, return *+∞*𝔽. Otherwise, return *+0*𝔽.
+ 1. If _exponent_ > *+0*𝔽, return *+∞*𝔽.
+ 1. Return *+0*𝔽.
1. If _base_ is *-∞*𝔽, then
1. If _exponent_ > *+0*𝔽, then
- 1. If _exponent_ is an odd integral Number, return *-∞*𝔽. Otherwise, return *+∞*𝔽.
- 1. Else,
- 1. If _exponent_ is an odd integral Number, return *-0*𝔽. Otherwise, return *+0*𝔽.
+ 1. If _exponent_ is an odd integral Number, return *-∞*𝔽.
+ 1. Return *+∞*𝔽.
+ 1. If _exponent_ is an odd integral Number, return *-0*𝔽.
+ 1. Return *+0*𝔽.
1. If _base_ is *+0*𝔽, then
- 1. If _exponent_ > *+0*𝔽, return *+0*𝔽. Otherwise, return *+∞*𝔽.
+ 1. If _exponent_ > *+0*𝔽, return *+0*𝔽.
+ 1. Return *+∞*𝔽.
1. If _base_ is *-0*𝔽, then
1. If _exponent_ > *+0*𝔽, then
- 1. If _exponent_ is an odd integral Number, return *-0*𝔽. Otherwise, return *+0*𝔽.
- 1. Else,
- 1. If _exponent_ is an odd integral Number, return *-∞*𝔽. Otherwise, return *+∞*𝔽.
+ 1. If _exponent_ is an odd integral Number, return *-0*𝔽.
+ 1. Return *+0*𝔽.
+ 1. If _exponent_ is an odd integral Number, return *-∞*𝔽.
+ 1. Return *+∞*𝔽.
1. Assert: _base_ is finite and is neither *+0*𝔽 nor *-0*𝔽.
1. If _exponent_ is *+∞*𝔽, then
1. If abs(ℝ(_base_)) > 1, return *+∞*𝔽.
1. If abs(ℝ(_base_)) = 1, return *NaN*.
- 1. If abs(ℝ(_base_)) < 1, return *+0*𝔽.
+ 1. Return *+0*𝔽.
1. If _exponent_ is *-∞*𝔽, then
1. If abs(ℝ(_base_)) > 1, return *+0*𝔽.
1. If abs(ℝ(_base_)) = 1, return *NaN*.
- 1. If abs(ℝ(_base_)) < 1, return *+∞*𝔽.
+ 1. Return *+∞*𝔽.
1. Assert: _exponent_ is finite and is neither *+0*𝔽 nor *-0*𝔽.
1. If _base_ < *-0*𝔽 and _exponent_ is not an integral Number, return *NaN*.
1. Return an implementation-approximated Number value representing the result of raising ℝ(_base_) to the ℝ(_exponent_) power.
@@ -1950,10 +2089,10 @@
1. Return -_y_.
1. If _x_ is *-0*𝔽, then
1. If _y_ is *-0*𝔽 or _y_ < *-0*𝔽, return *+0*𝔽.
- 1. Else, return *-0*𝔽.
+ 1. Return *-0*𝔽.
1. If _y_ is *-0*𝔽, then
1. If _x_ < *-0*𝔽, return *+0*𝔽.
- 1. Else, return *-0*𝔽.
+ 1. Return *-0*𝔽.
1. Return 𝔽(ℝ(_x_) × ℝ(_y_)).
@@ -1979,17 +2118,21 @@
1. If _y_ is *+0*𝔽 or _y_ > *+0*𝔽, return _x_.
1. Return -_x_.
1. If _y_ is *+∞*𝔽, then
- 1. If _x_ is *+0*𝔽 or _x_ > *+0*𝔽, return *+0*𝔽. Otherwise, return *-0*𝔽.
+ 1. If _x_ is *+0*𝔽 or _x_ > *+0*𝔽, return *+0*𝔽.
+ 1. Return *-0*𝔽.
1. If _y_ is *-∞*𝔽, then
- 1. If _x_ is *+0*𝔽 or _x_ > *+0*𝔽, return *-0*𝔽. Otherwise, return *+0*𝔽.
+ 1. If _x_ is *+0*𝔽 or _x_ > *+0*𝔽, return *-0*𝔽.
+ 1. Return *+0*𝔽.
1. If _x_ is either *+0*𝔽 or *-0*𝔽, then
1. If _y_ is either *+0*𝔽 or *-0*𝔽, return *NaN*.
1. If _y_ > *+0*𝔽, return _x_.
1. Return -_x_.
1. If _y_ is *+0*𝔽, then
- 1. If _x_ > *+0*𝔽, return *+∞*𝔽. Otherwise, return *-∞*𝔽.
+ 1. If _x_ > *+0*𝔽, return *+∞*𝔽.
+ 1. Return *-∞*𝔽.
1. If _y_ is *-0*𝔽, then
- 1. If _x_ > *+0*𝔽, return *-∞*𝔽. Otherwise, return *+∞*𝔽.
+ 1. If _x_ > *+0*𝔽, return *-∞*𝔽.
+ 1. Return *+∞*𝔽.
1. Return 𝔽(ℝ(_x_) / ℝ(_y_)).
@@ -1997,26 +2140,26 @@
Number::remainder (
- _n_: a Number,
- _d_: a Number,
+ _numerator_: a Number,
+ _denominator_: a Number,
): a Number
- description
- - It yields the remainder from an implied division of its operands where _n_ is the dividend and _d_ is the divisor.
+ - It yields the remainder from an implied division of its operands where _numerator_ is the dividend and _denominator_ is the divisor.
- 1. If _n_ is *NaN* or _d_ is *NaN*, return *NaN*.
- 1. If _n_ is either *+∞*𝔽 or *-∞*𝔽, return *NaN*.
- 1. If _d_ is either *+∞*𝔽 or *-∞*𝔽, return _n_.
- 1. If _d_ is either *+0*𝔽 or *-0*𝔽, return *NaN*.
- 1. If _n_ is either *+0*𝔽 or *-0*𝔽, return _n_.
- 1. Assert: _n_ and _d_ are finite and non-zero.
- 1. Let _quotient_ be ℝ(_n_) / ℝ(_d_).
- 1. Let _q_ be truncate(_quotient_).
- 1. Let _r_ be ℝ(_n_) - (ℝ(_d_) × _q_).
- 1. If _r_ = 0 and _n_ < *-0*𝔽, return *-0*𝔽.
- 1. Return 𝔽(_r_).
+ 1. If _numerator_ is *NaN* or _denominator_ is *NaN*, return *NaN*.
+ 1. If _numerator_ is either *+∞*𝔽 or *-∞*𝔽, return *NaN*.
+ 1. If _denominator_ is either *+∞*𝔽 or *-∞*𝔽, return _numerator_.
+ 1. If _denominator_ is either *+0*𝔽 or *-0*𝔽, return *NaN*.
+ 1. If _numerator_ is either *+0*𝔽 or *-0*𝔽, return _numerator_.
+ 1. Assert: _numerator_ and _denominator_ are finite and non-zero.
+ 1. Let _quotient_ be ℝ(_numerator_) / ℝ(_denominator_).
+ 1. Let _truncatedQuotient_ be truncate(_quotient_).
+ 1. Let _remainder_ be ℝ(_numerator_) - (ℝ(_denominator_) × _truncatedQuotient_).
+ 1. If _remainder_ = 0 and _numerator_ < *-0*𝔽, return *-0*𝔽.
+ 1. Return 𝔽(_remainder_).
In C and C++, the remainder operator accepts only integral operands; in ECMAScript, it also accepts floating-point operands.
@@ -2079,10 +2222,10 @@
- 1. Let _lnum_ be ! ToInt32(_x_).
- 1. Let _rnum_ be ! ToUint32(_y_).
- 1. Let _shiftCount_ be ℝ(_rnum_) modulo 32.
- 1. Return the result of left shifting _lnum_ by _shiftCount_ bits. The mathematical value of the result is exactly representable as a 32-bit two's complement bit string.
+ 1. Let _leftNumber_ be ! ToInt32(_x_).
+ 1. Let _rightNumber_ be ! ToUint32(_y_).
+ 1. Let _shiftCount_ be ℝ(_rightNumber_) modulo 32.
+ 1. Return the result of left shifting _leftNumber_ by _shiftCount_ bits. The mathematical value of the result is exactly representable as a 32-bit two's complement bit string.
@@ -2096,10 +2239,10 @@
- 1. Let _lnum_ be ! ToInt32(_x_).
- 1. Let _rnum_ be ! ToUint32(_y_).
- 1. Let _shiftCount_ be ℝ(_rnum_) modulo 32.
- 1. Return the result of performing a sign-extending right shift of _lnum_ by _shiftCount_ bits. The most significant bit is propagated. The mathematical value of the result is exactly representable as a 32-bit two's complement bit string.
+ 1. Let _leftNumber_ be ! ToInt32(_x_).
+ 1. Let _rightNumber_ be ! ToUint32(_y_).
+ 1. Let _shiftCount_ be ℝ(_rightNumber_) modulo 32.
+ 1. Return the result of performing a sign-extending right shift of _leftNumber_ by _shiftCount_ bits. The most significant bit is propagated. The mathematical value of the result is exactly representable as a 32-bit two's complement bit string.
@@ -2113,10 +2256,10 @@
- 1. Let _lnum_ be ! ToUint32(_x_).
- 1. Let _rnum_ be ! ToUint32(_y_).
- 1. Let _shiftCount_ be ℝ(_rnum_) modulo 32.
- 1. Return the result of performing a zero-filling right shift of _lnum_ by _shiftCount_ bits. Vacated bits are filled with zero. The mathematical value of the result is exactly representable as a 32-bit unsigned bit string.
+ 1. Let _leftNumber_ be ! ToUint32(_x_).
+ 1. Let _rightNumber_ be ! ToUint32(_y_).
+ 1. Let _shiftCount_ be ℝ(_rightNumber_) modulo 32.
+ 1. Return the result of performing a zero-filling right shift of _leftNumber_ by _shiftCount_ bits. Vacated bits are filled with zero. The mathematical value of the result is exactly representable as a 32-bit unsigned bit string.
@@ -2140,7 +2283,8 @@
1. If _y_ is *-∞*𝔽, return *false*.
1. If _x_ is *-∞*𝔽, return *true*.
1. Assert: _x_ and _y_ are finite.
- 1. If ℝ(_x_) < ℝ(_y_), return *true*. Otherwise, return *false*.
+ 1. If ℝ(_x_) < ℝ(_y_), return *true*.
+ 1. Return *false*.
@@ -2210,17 +2354,17 @@
- 1. Let _lnum_ be ! ToInt32(_x_).
- 1. Let _rnum_ be ! ToInt32(_y_).
- 1. Let _lbits_ be the 32-bit two's complement bit string representing ℝ(_lnum_).
- 1. Let _rbits_ be the 32-bit two's complement bit string representing ℝ(_rnum_).
+ 1. Let _leftNumber_ be ! ToInt32(_x_).
+ 1. Let _rightNumber_ be ! ToInt32(_y_).
+ 1. Let _leftBits_ be the 32-bit two's complement bit string representing ℝ(_leftNumber_).
+ 1. Let _rightBits_ be the 32-bit two's complement bit string representing ℝ(_rightNumber_).
1. If _op_ is `&`, then
- 1. Let _result_ be the result of applying the bitwise AND operation to _lbits_ and _rbits_.
+ 1. Let _result_ be the result of applying the bitwise AND operation to _leftBits_ and _rightBits_.
1. Else if _op_ is `^`, then
- 1. Let _result_ be the result of applying the bitwise exclusive OR (XOR) operation to _lbits_ and _rbits_.
+ 1. Let _result_ be the result of applying the bitwise exclusive OR (XOR) operation to _leftBits_ and _rightBits_.
1. Else,
1. Assert: _op_ is `|`.
- 1. Let _result_ be the result of applying the bitwise inclusive OR operation to _lbits_ and _rbits_.
+ 1. Let _result_ be the result of applying the bitwise inclusive OR operation to _leftBits_ and _rightBits_.
1. Return the Number value for the integer represented by the 32-bit two's complement bit string _result_.
@@ -2289,18 +2433,17 @@
1. Return the string-concatenation of:
* the code units of the _k_ digits of the representation of _s_ using radix _radix_
* _n_ - _k_ occurrences of the code unit 0x0030 (DIGIT ZERO)
- 1. Else if _n_ > 0, then
+ 1. If _n_ > 0, then
1. Return the string-concatenation of:
* the code units of the most significant _n_ digits of the representation of _s_ using radix _radix_
* the code unit 0x002E (FULL STOP)
* the code units of the remaining _k_ - _n_ digits of the representation of _s_ using radix _radix_
- 1. Else,
- 1. Assert: _n_ ≤ 0.
- 1. Return the string-concatenation of:
- * the code unit 0x0030 (DIGIT ZERO)
- * the code unit 0x002E (FULL STOP)
- * -_n_ occurrences of the code unit 0x0030 (DIGIT ZERO)
- * the code units of the _k_ digits of the representation of _s_ using radix _radix_
+ 1. Assert: _n_ ≤ 0.
+ 1. Return the string-concatenation of:
+ * the code unit 0x0030 (DIGIT ZERO)
+ * the code unit 0x002E (FULL STOP)
+ * -_n_ occurrences of the code unit 0x0030 (DIGIT ZERO)
+ * the code units of the _k_ digits of the representation of _s_ using radix _radix_
1. NOTE: In this case, the input will be represented using scientific E notation, such as `1.2e+3`.
1. Assert: _radix_ is 10.
1. If _n_ < 0, then
@@ -2335,14 +2478,14 @@
For implementations that provide more accurate conversions than required by the rules above, it is recommended that the following alternative version of step
- 1. Let _n_, _k_, and _s_ be integers such that _k_ ≥ 1, _radix__k_ - 1 ≤ _s_ < _radix__k_, 𝔽(_s_ × _radix__n_ - _k_) is _x_, and _k_ is as small as possible. If there are multiple possibilities for _s_, choose the value of _s_ for which _s_ × _radix__n_ - _k_ is closest in value to ℝ(_x_). If there are two such possible values of _s_, choose the one that is even. Note that _k_ is the number of digits in the representation of _s_ using radix _radix_ and that _s_ is not divisible by _radix_.
+ 1. Let _n_, _k_, and _s_ be integers such that _k_ ≥ 1, _radix__k_ - 1 ≤ _s_ < _radix__k_, 𝔽(_s_ × _radix__n_ - _k_) is _x_, and _k_ is as small as possible. If there are multiple possibilities for _s_, choose _s_ such that _s_ × _radix__n_ - _k_ is closest to ℝ(_x_). If there are two such possible values of _s_, choose the one that is even. Note that _k_ is the number of digits in the representation of _s_ using radix _radix_ and that _s_ is not divisible by _radix_.
Implementers of ECMAScript may find useful the paper and code written by David M. Gay for binary-to-decimal conversion of floating-point numbers:
Gay, David M. Correctly Rounded Binary-Decimal and Decimal-Binary Conversions. Numerical Analysis, Manuscript 90-10. AT&T Bell Laboratories (Murray Hill, New Jersey). 30 November 1990. Available as
- http://ampl.com/REFS/abstracts.html#rounding. Associated code available as
+ https://ampl.com/_archive/first-website/REFS/rounding.pdf. Associated code available as
http://netlib.sandia.gov/fp/dtoa.c and as
http://netlib.sandia.gov/fp/g_fmt.c and may also be found at the various `netlib` mirror sites.
@@ -2357,29 +2500,29 @@ The BigInt Type
BigInt::unaryMinus (
- _x_: a BigInt,
+ _bigint_: a BigInt,
): a BigInt
- 1. If _x_ = *0*ℤ, return *0*ℤ.
- 1. Return -_x_.
+ 1. If _bigint_ = *0*ℤ, return *0*ℤ.
+ 1. Return -_bigint_.
BigInt::bitwiseNOT (
- _x_: a BigInt,
+ _bigint_: a BigInt,
): a BigInt
- description
- - It returns the one's complement of _x_.
+ - It returns the one's complement of _bigint_.
- 1. Return -_x_ - *1*ℤ.
+ 1. Return -_bigint_ - *1*ℤ.
@@ -2433,18 +2576,18 @@
BigInt::remainder (
- _n_: a BigInt,
- _d_: a BigInt,
+ _numerator_: a BigInt,
+ _denominator_: a BigInt,
): either a normal completion containing a BigInt or a throw completion
- 1. If _d_ = *0*ℤ, throw a *RangeError* exception.
- 1. If _n_ = *0*ℤ, return *0*ℤ.
- 1. Let _quotient_ be ℝ(_n_) / ℝ(_d_).
- 1. Let _q_ be ℤ(truncate(_quotient_)).
- 1. Return _n_ - (_d_ × _q_).
+ 1. If _denominator_ = *0*ℤ, throw a *RangeError* exception.
+ 1. If _numerator_ = *0*ℤ, return *0*ℤ.
+ 1. Let _quotient_ be ℝ(_numerator_) / ℝ(_denominator_).
+ 1. Let _truncatedQuotient_ be ℤ(truncate(_quotient_)).
+ 1. Return _numerator_ - (_denominator_ × _truncatedQuotient_).
The sign of the result is the sign of the dividend.
@@ -2532,7 +2675,8 @@
- 1. If ℝ(_x_) < ℝ(_y_), return *true*; otherwise return *false*.
+ 1. If ℝ(_x_) < ℝ(_y_), return *true*.
+ 1. Return *false*.
@@ -2546,7 +2690,8 @@
- 1. If ℝ(_x_) = ℝ(_y_), return *true*; otherwise return *false*.
+ 1. If ℝ(_x_) = ℝ(_y_), return *true*.
+ 1. Return *false*.
@@ -2561,7 +2706,7 @@
1. If _x_ = 1 and _y_ = 1, return 1.
- 1. Else, return 0.
+ 1. Return 0.
@@ -2576,7 +2721,7 @@
1. If _x_ = 1 or _y_ = 1, return 1.
- 1. Else, return 0.
+ 1. Return 0.
@@ -2591,8 +2736,8 @@
1. If _x_ = 1 and _y_ = 0, return 1.
- 1. Else if _x_ = 0 and _y_ = 1, return 1.
- 1. Else, return 0.
+ 1. If _x_ = 0 and _y_ = 1, return 1.
+ 1. Return 0.
@@ -2625,13 +2770,13 @@
1. Set _x_ to (_x_ - _xDigit_) / 2.
1. Set _y_ to (_y_ - _yDigit_) / 2.
1. If _op_ is `&`, then
- 1. Let _tmp_ be BinaryAnd(_x_ modulo 2, _y_ modulo 2).
+ 1. Let _signBit_ be BinaryAnd(_x_ modulo 2, _y_ modulo 2).
1. Else if _op_ is `|`, then
- 1. Let _tmp_ be BinaryOr(_x_ modulo 2, _y_ modulo 2).
+ 1. Let _signBit_ be BinaryOr(_x_ modulo 2, _y_ modulo 2).
1. Else,
1. Assert: _op_ is `^`.
- 1. Let _tmp_ be BinaryXor(_x_ modulo 2, _y_ modulo 2).
- 1. If _tmp_ ≠ 0, then
+ 1. Let _signBit_ be BinaryXor(_x_ modulo 2, _y_ modulo 2).
+ 1. If _signBit_ ≠ 0, then
1. Set _result_ to _result_ - 2_shift_.
1. NOTE: This extends the sign.
1. Return the BigInt value for _result_.
@@ -2710,7 +2855,7 @@ The Object Type
An accessor property associates a key value with one or two accessor functions, and a set of Boolean attributes. The accessor functions are used to store or retrieve an ECMAScript language value that is associated with the property.
-
The properties of an object are uniquely identified using property keys. A property key is either a String or a Symbol. All Strings and Symbols, including the empty String, are valid as property keys. A property name is a property key that is a String.
+ The properties of an object are uniquely identified using property keys. A property key is either a String or a Symbol. All Strings and Symbols, including the empty String, are valid as property keys. A property name is a property key that is a String.
An integer index is a property name _n_ such that CanonicalNumericIndexString(_n_) returns an integral Number in the inclusive interval from *+0*𝔽 to 𝔽(253 - 1). An array index is an integer index _n_ such that CanonicalNumericIndexString(_n_) returns an integral Number in the inclusive interval from *+0*𝔽 to 𝔽(232 - 2).
Every non-negative safe integer has a corresponding integer index. Every 32-bit unsigned integer except 232 - 1 has a corresponding array index. *"-0"* is neither an integer index nor an array index.
@@ -2724,13 +2869,15 @@ Property Attributes
Attributes are used in this specification to define and explain the state of Object properties as described in
-
- Attribute Name
- Types of property for which it is present
- Value Domain
- Default Value
- Description
-
+
+
+ Attribute Name
+ Types of property for which it is present
+ Value Domain
+ Default Value
+ Description
+
+
[[Value]]
@@ -2767,36 +2914,36 @@ Property Attributes
- [[Get]]
+ [[Getter]]
accessor property
- an Object or *undefined*
+ a function object or *undefined*
*undefined*
- If the value is an Object it must be a function object. The function's [[Call]] internal method (
- [[Set]]
+ [[Setter]]
accessor property
- an Object or *undefined*
+ a function object or *undefined*
*undefined*
- If the value is an Object it must be a function object. The function's [[Call]] internal method (
@@ -2841,7 +2988,7 @@ Property Attributes
Object Internal Methods and Internal Slots
The actual semantics of objects, in ECMAScript, are specified via algorithms called internal methods. Each object in an ECMAScript engine is associated with a set of internal methods that defines its runtime behaviour. These internal methods are not part of the ECMAScript language. They are defined by this specification purely for expository purposes. However, each object within an implementation of ECMAScript must behave as specified by the internal methods associated with it. The exact manner in which this is accomplished is determined by the implementation.
Internal method names are polymorphic. This means that different object values may perform different algorithms when a common internal method name is invoked upon them. That actual object upon which an internal method is invoked is the “target” of the invocation. If, at runtime, the implementation of an algorithm attempts to use an internal method of an object that the object does not support, a *TypeError* exception is thrown.
- Internal slots correspond to internal state that is associated with objects and used by various ECMAScript specification algorithms. Internal slots are not object properties and they are not inherited. Depending upon the specific internal slot specification, such state may consist of values of any ECMAScript language type or of specific ECMAScript specification type values. Unless explicitly specified otherwise, internal slots are allocated as part of the process of creating an object and may not be dynamically added to an object. Unless specified otherwise, the initial value of an internal slot is the value *undefined*. Various algorithms within this specification create objects that have internal slots. However, the ECMAScript language provides no direct way to associate internal slots with an object.
+ Internal slots correspond to internal state that is associated with objects, Symbols, or Private Names and used by various ECMAScript specification algorithms. Internal slots are not object properties and they are not inherited. Depending upon the specific internal slot specification, such state may consist of values of any ECMAScript language type or of specific ECMAScript specification type values. Unless explicitly specified otherwise, internal slots are allocated as part of the process of creating an object, Symbol, or Private Name and may not be dynamically added. Unless specified otherwise, the initial value of an internal slot is the value *undefined*. Various algorithms within this specification create values that have internal slots. However, the ECMAScript language provides no direct way to manipulate internal slots.
All objects have an internal slot named [[PrivateElements]], which is a List of PrivateElements. This List represents the values of the private fields, methods, and accessors for the object. Initially, it is an empty List.
Internal methods and internal slots are identified within this specification using names enclosed in double square brackets [[ ]].
@@ -2864,17 +3011,19 @@ Object Internal Methods and Internal Slots
An internal method implicitly returns a Completion Record, either a normal completion that wraps a value of the return type shown in its invocation pattern, or a throw completion.
-
-
- Internal Method
-
-
- Signature
-
-
- Description
-
-
+
+
+
+ Internal Method
+
+
+ Signature
+
+
+ Description
+
+
+
[[GetPrototypeOf]]
@@ -2935,10 +3084,10 @@ Object Internal Methods and Internal Slots
[[DefineOwnProperty]]
- (_propertyKey_, _PropertyDescriptor_) → Boolean
+ (_propertyKey_, _propertyDesc_) → Boolean
- Create or alter the own property, whose key is _propertyKey_, to have the state described by _PropertyDescriptor_. Return *true* if that property was successfully created/updated or *false* if the property could not be created or updated.
+ Create or alter the own property, whose key is _propertyKey_, to have the state described by _propertyDesc_. Return *true* if that property was successfully created/updated or *false* if the property could not be created or updated.
@@ -2957,10 +3106,10 @@ Object Internal Methods and Internal Slots
[[Get]]
- (_propertyKey_, _Receiver_) → any
+ (_propertyKey_, _receiver_) → any
- Return the value of the property whose key is _propertyKey_ from this object. If any ECMAScript code must be executed to retrieve the property value, _Receiver_ is used as the *this* value when evaluating the code.
+ Return the value of the property whose key is _propertyKey_ from this object. If any ECMAScript code must be executed to retrieve the property value, _receiver_ is used as the *this* value when evaluating the code.
@@ -2968,10 +3117,10 @@ Object Internal Methods and Internal Slots
[[Set]]
- (_propertyKey_, _value_, _Receiver_) → Boolean
+ (_propertyKey_, _value_, _receiver_) → Boolean
- Set the value of the property whose key is _propertyKey_ to _value_. If any ECMAScript code must be executed to set the property value, _Receiver_ is used as the *this* value when evaluating the code. Returns *true* if the property value was set or *false* if it could not be set.
+ Set the value of the property whose key is _propertyKey_ to _value_. If any ECMAScript code must be executed to set the property value, _receiver_ is used as the *this* value when evaluating the code. Returns *true* if the property value was set or *false* if it could not be set.
@@ -3001,17 +3150,19 @@ Object Internal Methods and Internal Slots
-
-
- Internal Method
-
-
- Signature
-
-
- Description
-
-
+
+
+
+ Internal Method
+
+
+ Signature
+
+
+ Description
+
+
+
[[Call]]
@@ -3062,7 +3213,7 @@ Definitions:
Return value:
The value returned by any internal method must be a Completion Record with either:
- - [[Type]] = ~normal~, [[Target]] = ~empty~, and [[Value]] = a value of the "normal return type" shown below for that internal method, or
+ - [[Type]] = ~normal~, [[Target]] = ~empty~, and [[Value]] = a value of the “normal return type” shown below for that internal method, or
- [[Type]] = ~throw~, [[Target]] = ~empty~, and [[Value]] = any ECMAScript language value.
@@ -3074,19 +3225,19 @@ [[GetPrototypeOf]] ( )
The normal return type is either Object or Null.
- If target is non-extensible, and [[GetPrototypeOf]] returns a value _V_, then any future calls to [[GetPrototypeOf]] should return the SameValue as _V_.
+ If target is non-extensible, and [[GetPrototypeOf]] returns a value _proto_, then any future calls to [[GetPrototypeOf]] should return the SameValue as _proto_.
An object's prototype chain should have finite length (that is, starting from any object, recursively applying the [[GetPrototypeOf]] internal method to its result should eventually lead to the value *null*). However, this requirement is not enforceable as an object level invariant if the prototype chain includes any exotic objects that do not use the ordinary object definition of [[GetPrototypeOf]]. Such a circular prototype chain may result in infinite loops when accessing object properties.
- [[SetPrototypeOf]] ( _V_ )
+ [[SetPrototypeOf]] ( _proto_ )
-
The normal return type is Boolean.
-
- If target is non-extensible, [[SetPrototypeOf]] must return *false*, unless _V_ is the SameValue as the target's observed [[GetPrototypeOf]] value.
+ If target is non-extensible, [[SetPrototypeOf]] must return *false*, unless _proto_ is the SameValue as the target's observed [[GetPrototypeOf]] value.
[[IsExtensible]] ( )
@@ -3107,90 +3258,90 @@ [[PreventExtensions]] ( )
If [[PreventExtensions]] returns *true*, all future calls to [[IsExtensible]] on the target must return *false* and the target is now considered non-extensible.
- [[GetOwnProperty]] ( _P_ )
+ [[GetOwnProperty]] ( _propertyKey_ )
-
The normal return type is either Property Descriptor or Undefined.
-
- If the Type of the return value is Property Descriptor, the return value must be a fully populated Property Descriptor.
+ If the return value is a Property Descriptor, it must be a fully populated Property Descriptor.
-
- If _P_ is described as a non-configurable, non-writable own data property, all future calls to [[GetOwnProperty]] ( _P_ ) must return Property Descriptor whose [[Value]] is SameValue as _P_'s [[Value]] attribute.
+ If _propertyKey_ is described as a non-configurable, non-writable own data property, all future calls to [[GetOwnProperty]] ( _propertyKey_ ) must return Property Descriptor whose [[Value]] is SameValue as _propertyKey_'s [[Value]] attribute.
-
- If _P_'s attributes other than [[Writable]] and [[Value]] may change over time, or if the property might be deleted, then _P_'s [[Configurable]] attribute must be *true*.
+ If _propertyKey_'s attributes other than [[Writable]] and [[Value]] may change over time, or if the property might be deleted, then _propertyKey_'s [[Configurable]] attribute must be *true*.
-
If the [[Writable]] attribute may change from *false* to *true*, then the [[Configurable]] attribute must be *true*.
-
- If the target is non-extensible and _P_ is non-existent, then all future calls to [[GetOwnProperty]] (_P_) on the target must describe _P_ as non-existent (i.e. [[GetOwnProperty]] (_P_) must return *undefined*).
+ If the target is non-extensible and _propertyKey_ is non-existent, then all future calls to [[GetOwnProperty]] (_propertyKey_) on the target must describe _propertyKey_ as non-existent (i.e. [[GetOwnProperty]] (_propertyKey_) must return *undefined*).
As a consequence of the third invariant, if a property is described as a data property and it may return different values over time, then either or both of the [[Writable]] and [[Configurable]] attributes must be *true* even if no mechanism to change the value is exposed via the other essential internal methods.
- [[DefineOwnProperty]] ( _P_, _Desc_ )
+ [[DefineOwnProperty]] ( _propertyKey_, _propertyDesc_ )
-
The normal return type is Boolean.
-
- [[DefineOwnProperty]] must return *false* if _P_ has previously been observed as a non-configurable own property of the target, unless either:
+ [[DefineOwnProperty]] must return *false* if _propertyKey_ has previously been observed as a non-configurable own property of the target, unless either:
-
- _P_ is a writable data property. A non-configurable writable data property can be changed into a non-configurable non-writable data property.
+ _propertyKey_ is a writable data property. A non-configurable writable data property can be changed into a non-configurable non-writable data property.
-
- All attributes of _Desc_ are the SameValue as _P_'s attributes.
+ All attributes of _propertyDesc_ are the SameValue as _propertyKey_'s attributes.
-
- [[DefineOwnProperty]] (_P_, _Desc_) must return *false* if target is non-extensible and _P_ is a non-existent own property. That is, a non-extensible target object cannot be extended with new properties.
+ [[DefineOwnProperty]] (_propertyKey_, _propertyDesc_) must return *false* if target is non-extensible and _propertyKey_ is a non-existent own property. That is, a non-extensible target object cannot be extended with new properties.
- [[HasProperty]] ( _P_ )
+ [[HasProperty]] ( _propertyKey_ )
-
The normal return type is Boolean.
-
- If _P_ was previously observed as a non-configurable own data or accessor property of the target, [[HasProperty]] must return *true*.
+ If _propertyKey_ was previously observed as a non-configurable own data or accessor property of the target, [[HasProperty]] must return *true*.
- [[Get]] ( _P_, _Receiver_ )
+ [[Get]] ( _propertyKey_, _receiver_ )
-
The normal return type is any ECMAScript language type.
-
- If _P_ was previously observed as a non-configurable, non-writable own data property of the target with value _V_, then [[Get]] must return the SameValue as _V_.
+ If _propertyKey_ was previously observed as a non-configurable, non-writable own data property of the target with value _value_, then [[Get]] must return the SameValue as _value_.
-
- If _P_ was previously observed as a non-configurable own accessor property of the target whose [[Get]] attribute is *undefined*, the [[Get]] operation must return *undefined*.
+ If _propertyKey_ was previously observed as a non-configurable own accessor property of the target whose [[Getter]] attribute is *undefined*, the [[Get]] operation must return *undefined*.
- [[Set]] ( _P_, _V_, _Receiver_ )
+ [[Set]] ( _propertyKey_, _value_, _receiver_ )
-
The normal return type is Boolean.
-
- If _P_ was previously observed as a non-configurable, non-writable own data property of the target, then [[Set]] must return *false* unless _V_ is the SameValue as _P_'s [[Value]] attribute.
+ If _propertyKey_ was previously observed as a non-configurable, non-writable own data property of the target, then [[Set]] must return *false* unless _value_ is the SameValue as _propertyKey_'s [[Value]] attribute.
-
- If _P_ was previously observed as a non-configurable own accessor property of the target whose [[Set]] attribute is *undefined*, the [[Set]] operation must return *false*.
+ If _propertyKey_ was previously observed as a non-configurable own accessor property of the target whose [[Setter]] attribute is *undefined*, the [[Set]] operation must return *false*.
- [[Delete]] ( _P_ )
+ [[Delete]] ( _propertyKey_ )
-
The normal return type is Boolean.
-
- If _P_ was previously observed as a non-configurable own data or accessor property of the target, [[Delete]] must return *false*.
+ If _propertyKey_ was previously observed as a non-configurable own data or accessor property of the target, [[Delete]] must return *false*.
[[OwnPropertyKeys]] ( )
@@ -3202,7 +3353,7 @@ [[OwnPropertyKeys]] ( )
The returned List must not contain any duplicate entries.
- The Type of each element of the returned List is either String or Symbol.
+ Each element of the returned List must be a property key.
The returned List must contain at least the keys of all non-configurable own properties that have previously been observed.
@@ -3234,26 +3385,28 @@ Well-Known Intrinsic Objects
Within this specification a reference such as %name% means the intrinsic object, associated with the current realm, corresponding to the name. A reference such as %name.a.b% means, as if the *"b"* property of the value of the *"a"* property of the intrinsic object %name% was accessed prior to any ECMAScript code being evaluated. Determination of the current realm and its intrinsics is described in
-
-
- Intrinsic Name
-
-
- Global Name
-
-
- ECMAScript Language Association
-
-
+
+
+
+ Intrinsic Name
+
+
+ Global Name
+
+
+ ECMAScript Language Association
+
+
+
%AggregateError%
- `AggregateError`
+ *"AggregateError"*
- The `AggregateError` constructor (constructor (
@@ -3261,10 +3414,10 @@ Well-Known Intrinsic Objects
%Array%
- `Array`
+ *"Array"*
- The Array constructor (constructor (
@@ -3272,10 +3425,10 @@ Well-Known Intrinsic Objects
%ArrayBuffer%
- `ArrayBuffer`
+ *"ArrayBuffer"*
- The ArrayBuffer constructor (constructor (
@@ -3285,7 +3438,18 @@ Well-Known Intrinsic Objects
- The prototype of Array iterator objects (
+
+
+
+ %AsyncDisposableStack%
+
+
+ *"AsyncDisposableStack"*
+
+
+ The `AsyncDisposableStack` constructor (
@@ -3295,7 +3459,7 @@ Well-Known Intrinsic Objects
- The prototype of async-from-sync iterator objects (
@@ -3305,7 +3469,7 @@ Well-Known Intrinsic Objects
- The constructor of async function objects (constructor of async function objects (
@@ -3315,7 +3479,7 @@ Well-Known Intrinsic Objects
- The constructor of async generator function objects (constructor of async generator function objects (
@@ -3343,7 +3507,7 @@ Well-Known Intrinsic Objects
%Atomics%
- `Atomics`
+ *"Atomics"*
The `Atomics` object (Well-Known Intrinsic Objects
%BigInt%
- `BigInt`
+ *"BigInt"*
- The BigInt constructor (constructor (
@@ -3365,10 +3529,10 @@ Well-Known Intrinsic Objects
%BigInt64Array%
- `BigInt64Array`
+ *"BigInt64Array"*
- The BigInt64Array constructor (constructor (
@@ -3376,10 +3540,10 @@ Well-Known Intrinsic Objects
%BigUint64Array%
- `BigUint64Array`
+ *"BigUint64Array"*
- The BigUint64Array constructor (constructor (
@@ -3387,10 +3551,10 @@ Well-Known Intrinsic Objects
%Boolean%
- `Boolean`
+ *"Boolean"*
- The Boolean constructor (constructor (
@@ -3398,10 +3562,10 @@ Well-Known Intrinsic Objects
%DataView%
- `DataView`
+ *"DataView"*
- The DataView constructor (constructor (
@@ -3409,10 +3573,10 @@ Well-Known Intrinsic Objects
%Date%
- `Date`
+ *"Date"*
- The Date constructor (constructor (
@@ -3420,7 +3584,7 @@ Well-Known Intrinsic Objects
%decodeURI%
- `decodeURI`
+ *"decodeURI"*
The `decodeURI` function (Well-Known Intrinsic Objects
%decodeURIComponent%
- `decodeURIComponent`
+ *"decodeURIComponent"*
The `decodeURIComponent` function (
+
+
+ %DisposableStack%
+
+
+ *"DisposableStack"*
+
+
+ The `DisposableStack` constructor (
+
%encodeURI%
- `encodeURI`
+ *"encodeURI"*
The `encodeURI` function (Well-Known Intrinsic Objects
%encodeURIComponent%
- `encodeURIComponent`
+ *"encodeURIComponent"*
The `encodeURIComponent` function (Well-Known Intrinsic Objects
%Error%
- `Error`
+ *"Error"*
- The Error constructor (constructor (
@@ -3475,7 +3650,7 @@ Well-Known Intrinsic Objects
%eval%
- `eval`
+ *"eval"*
The `eval` function (Well-Known Intrinsic Objects
%EvalError%
- `EvalError`
+ *"EvalError"*
- The EvalError constructor (constructor (
@@ -3497,10 +3672,21 @@ Well-Known Intrinsic Objects
%FinalizationRegistry%
- `FinalizationRegistry`
+ *"FinalizationRegistry"*
- The FinalizationRegistry constructor (constructor (
+
+
+
+ %Float16Array%
+
+
+ *"Float16Array"*
+
+
+ The `Float16Array` constructor (
@@ -3508,10 +3694,10 @@ Well-Known Intrinsic Objects
%Float32Array%
- `Float32Array`
+ *"Float32Array"*
- The Float32Array constructor (constructor (
@@ -3519,10 +3705,10 @@ Well-Known Intrinsic Objects
%Float64Array%
- `Float64Array`
+ *"Float64Array"*
- The Float64Array constructor (constructor (
@@ -3532,7 +3718,7 @@ Well-Known Intrinsic Objects
- The prototype of For-In iterator objects (
@@ -3540,10 +3726,10 @@ Well-Known Intrinsic Objects
%Function%
- `Function`
+ *"Function"*
- The Function constructor (constructor (
@@ -3553,7 +3739,7 @@ Well-Known Intrinsic Objects
- The constructor of generator function objects (constructor of generator function objects (
@@ -3571,10 +3757,10 @@ Well-Known Intrinsic Objects
%Int8Array%
- `Int8Array`
+ *"Int8Array"*
- The Int8Array constructor (constructor (
@@ -3582,10 +3768,10 @@ Well-Known Intrinsic Objects
%Int16Array%
- `Int16Array`
+ *"Int16Array"*
- The Int16Array constructor (constructor (
@@ -3593,10 +3779,10 @@ Well-Known Intrinsic Objects
%Int32Array%
- `Int32Array`
+ *"Int32Array"*
- The Int32Array constructor (constructor (
@@ -3604,7 +3790,7 @@ Well-Known Intrinsic Objects
%isFinite%
- `isFinite`
+ *"isFinite"*
The `isFinite` function (Well-Known Intrinsic Objects
%isNaN%
- `isNaN`
+ *"isNaN"*
The `isNaN` function (Well-Known Intrinsic Objects
- %IteratorPrototype%
+ %Iterator%
+ *"Iterator"*
- An object that all standard built-in iterator objects indirectly inherit from
+ The `Iterator` constructor (
+
+
+
+ %IteratorHelperPrototype%
+
+
+
+
+ The prototype of Iterator Helper objects (
@@ -3636,7 +3833,7 @@ Well-Known Intrinsic Objects
%JSON%
- `JSON`
+ *"JSON"*
The `JSON` object (Well-Known Intrinsic Objects
%Map%
- `Map`
+ *"Map"*
- The Map constructor (constructor (
@@ -3660,7 +3857,7 @@ Well-Known Intrinsic Objects
- The prototype of Map iterator objects (
@@ -3668,7 +3865,7 @@ Well-Known Intrinsic Objects
%Math%
- `Math`
+ *"Math"*
The `Math` object (Well-Known Intrinsic Objects
%Number%
- `Number`
+ *"Number"*
- The Number constructor (constructor (
@@ -3690,10 +3887,10 @@ Well-Known Intrinsic Objects
%Object%
- `Object`
+ *"Object"*
- The Object constructor (constructor (
@@ -3701,7 +3898,7 @@ Well-Known Intrinsic Objects
%parseFloat%
- `parseFloat`
+ *"parseFloat"*
The `parseFloat` function (Well-Known Intrinsic Objects
%parseInt%
- `parseInt`
+ *"parseInt"*
The `parseInt` function (Well-Known Intrinsic Objects
%Promise%
- `Promise`
+ *"Promise"*
- The Promise constructor (constructor (
@@ -3734,10 +3931,10 @@ Well-Known Intrinsic Objects
%Proxy%
- `Proxy`
+ *"Proxy"*
- The Proxy constructor (constructor (
@@ -3745,10 +3942,10 @@ Well-Known Intrinsic Objects
%RangeError%
- `RangeError`
+ *"RangeError"*
- The RangeError constructor (constructor (
@@ -3756,10 +3953,10 @@ Well-Known Intrinsic Objects
%ReferenceError%
- `ReferenceError`
+ *"ReferenceError"*
- The ReferenceError constructor (constructor (
@@ -3767,7 +3964,7 @@ Well-Known Intrinsic Objects
%Reflect%
- `Reflect`
+ *"Reflect"*
The `Reflect` object (Well-Known Intrinsic Objects
%RegExp%
- `RegExp`
+ *"RegExp"*
- The RegExp constructor (constructor (
@@ -3799,10 +3996,10 @@ Well-Known Intrinsic Objects
%Set%
- `Set`
+ *"Set"*
- The Set constructor (constructor (
@@ -3812,7 +4009,7 @@ Well-Known Intrinsic Objects
- The prototype of Set iterator objects (
@@ -3820,10 +4017,10 @@ Well-Known Intrinsic Objects
%SharedArrayBuffer%
- `SharedArrayBuffer`
+ *"SharedArrayBuffer"*
- The SharedArrayBuffer constructor (constructor (
@@ -3831,10 +4028,10 @@ Well-Known Intrinsic Objects
%String%
- `String`
+ *"String"*
- The String constructor (constructor (
@@ -3844,7 +4041,18 @@ Well-Known Intrinsic Objects
- The prototype of String iterator objects (
+
+
+
+ %SuppressedError%
+
+
+ *"SuppressedError"*
+
+
+ The `SuppressedError` constructor (
@@ -3852,10 +4060,10 @@ Well-Known Intrinsic Objects
%Symbol%
- `Symbol`
+ *"Symbol"*
- The Symbol constructor (constructor (
@@ -3863,10 +4071,10 @@ Well-Known Intrinsic Objects
%SyntaxError%
- `SyntaxError`
+ *"SyntaxError"*
- The SyntaxError constructor (constructor (
@@ -3886,7 +4094,7 @@ Well-Known Intrinsic Objects
- The super class of all typed Array constructors (constructors (
@@ -3894,10 +4102,10 @@ Well-Known Intrinsic Objects
%TypeError%
- `TypeError`
+ *"TypeError"*
- The TypeError constructor (constructor (
@@ -3905,10 +4113,10 @@ Well-Known Intrinsic Objects
%Uint8Array%
- `Uint8Array`
+ *"Uint8Array"*
- The Uint8Array constructor (constructor (
@@ -3916,10 +4124,10 @@ Well-Known Intrinsic Objects
%Uint8ClampedArray%
- `Uint8ClampedArray`
+ *"Uint8ClampedArray"*
- The Uint8ClampedArray constructor (constructor (
@@ -3927,10 +4135,10 @@ Well-Known Intrinsic Objects
%Uint16Array%
- `Uint16Array`
+ *"Uint16Array"*
- The Uint16Array constructor (constructor (
@@ -3938,10 +4146,10 @@ Well-Known Intrinsic Objects
%Uint32Array%
- `Uint32Array`
+ *"Uint32Array"*
- The Uint32Array constructor (constructor (
@@ -3949,10 +4157,10 @@ Well-Known Intrinsic Objects
%URIError%
- `URIError`
+ *"URIError"*
- The URIError constructor (constructor (
@@ -3960,10 +4168,10 @@ Well-Known Intrinsic Objects
%WeakMap%
- `WeakMap`
+ *"WeakMap"*
- The WeakMap constructor (constructor (
@@ -3971,10 +4179,10 @@ Well-Known Intrinsic Objects
%WeakRef%
- `WeakRef`
+ *"WeakRef"*
- The WeakRef constructor (constructor (
@@ -3982,10 +4190,20 @@ Well-Known Intrinsic Objects
%WeakSet%
- `WeakSet`
+ *"WeakSet"*
- The WeakSet constructor (constructor (
+
+
+
+ %WrapForValidIteratorPrototype%
+
+
+
+
+ The prototype of wrapped iterator objects returned by `Iterator.from` (
@@ -3999,30 +4217,30 @@ Well-Known Intrinsic Objects
ECMAScript Specification Types
- A specification type corresponds to meta-values that are used within algorithms to describe the semantics of ECMAScript language constructs and ECMAScript language types. The specification types include Reference, List, Completion Record, Property Descriptor, Environment Record, Abstract Closure, and Data Block. Specification type values are specification artefacts that do not necessarily correspond to any specific entity within an ECMAScript implementation. Specification type values may be used to describe intermediate results of ECMAScript expression evaluation but such values cannot be stored as properties of objects or values of ECMAScript language variables.
+ A specification type corresponds to meta-values that are used within algorithms to describe the semantics of ECMAScript language constructs and ECMAScript language types. The specification types include Reference Record, List, Completion Record, Property Descriptor, Environment Record, Abstract Closure, and Data Block. Specification type values are specification artefacts that do not necessarily correspond to any specific entity within an ECMAScript implementation. Specification type values may be used to describe intermediate results of ECMAScript expression evaluation but such values cannot be stored as properties of objects or values of ECMAScript language variables.
The Enum Specification Type
- Enums are values which are internal to the specification and not directly observable from ECMAScript code. Enums are denoted using a ~sans-serif~ typeface. For instance, a Completion Record's [[Type]] field takes on values like ~normal~, ~return~, or ~throw~. Enums have no characteristics other than their name. The name of an enum serves no purpose other than to distinguish it from other enums, and implies nothing about its usage or meaning in context.
+ Enums are values which are internal to the specification and not directly observable from ECMAScript code. Enums are denoted in upper kebab case using a ~sans-serif~ typeface. For instance, a Completion Record's [[Type]] field takes on values like ~normal~, ~return~, or ~throw~. Enums have no characteristics other than their name. The name of an enum serves no purpose other than to distinguish it from other enums, and implies nothing about its usage or meaning in context.
The List and Record Specification Types
- The List type is used to explain the evaluation of argument lists (see
+ The List type is used to explain the evaluation of argument lists (see
When an algorithm iterates over the elements of a List without specifying an order, the order used is the order of the elements in the List.
For notational convenience within this specification, a literal syntax can be used to express a new List value. For example, « 1, 2 » defines a List value that has two elements each of which is initialized to a specific value. A new empty List can be expressed as « ».
- In this specification, the phrase "the list-concatenation of _A_, _B_, ..." (where each argument is a possibly empty List) denotes a new List value whose elements are the concatenation of the elements (in order) of each of the arguments (in order).
- As applied to a List of Strings, the phrase "sorted according to lexicographic code unit order" means sorting by the numeric value of each code unit up to the length of the shorter string, and sorting the shorter string before the longer string if all are equal, as described in the abstract operation IsLessThan.
+ In this specification, the phrase “the list-concatenation of _A_, _B_, ...” (where each argument is a possibly empty List) denotes a new List value whose elements are the concatenation of the elements (in order) of each of the arguments (in order).
+ As applied to a List of Strings, the phrase “sorted according to lexicographic code unit order” means sorting by the numeric value of each code unit up to the length of the shorter string, and sorting the shorter string before the longer string if all are equal, as described in the abstract operation IsLessThan.
The Record type is used to describe data aggregations within the algorithms of this specification. A Record type value consists of one or more named fields. The value of each field is an ECMAScript language value or specification value. Field names are always enclosed in double brackets, for example [[Value]].
- For notational convenience within this specification, an object literal-like syntax can be used to express a Record value. For example, { [[Field1]]: 42, [[Field2]]: *false*, [[Field3]]: ~empty~ } defines a Record value that has three fields, each of which is initialized to a specific value. Field name order is not significant. Any fields that are not explicitly listed are considered to be absent.
- In specification text and algorithms, dot notation may be used to refer to a specific field of a Record value. For example, if R is the record shown in the previous paragraph then R.[[Field2]] is shorthand for “the field of R named [[Field2]]”.
- Schema for commonly used Record field combinations may be named, and that name may be used as a prefix to a literal Record value to identify the specific kind of aggregations that is being described. For example: PropertyDescriptor { [[Value]]: 42, [[Writable]]: *false*, [[Configurable]]: *true* }.
+ For notational convenience within this specification, an object literal-like syntax can be used to express a Record. For example, { [[Field1]]: 42, [[Field2]]: *false*, [[Field3]]: ~empty~ } defines a Record that has three fields, each of which is initialized to a specific value. Field name order is not significant. Any fields that are not explicitly listed are considered to be absent.
+ In specification text and algorithms, dot notation may be used to refer to a specific field of a Record. For example, if R is the record shown in the previous paragraph then R.[[Field2]] is shorthand for “the field of R named [[Field2]]”.
+ Schema for commonly used Record field combinations may be named, and that name may be used as a prefix to a literal Record to identify the specific kind of aggregations that is being described. For example: PropertyDescriptor { [[Value]]: 42, [[Writable]]: *false*, [[Configurable]]: *true* }.
The Set and Relation Specification Types
- The Set type is used to explain a collection of unordered elements for use in the memory model. It is distinct from the ECMAScript collection type of the same name. To disambiguate, instances of the ECMAScript collection are consistently referred to as "Set objects" within this specification. Values of the Set type are simple collections of elements, where no element appears more than once. Elements may be added to and removed from Sets. Sets may be unioned, intersected, or subtracted from each other.
- The Relation type is used to explain constraints on Sets. Values of the Relation type are Sets of ordered pairs of values from its value domain. For example, a Relation on events is a set of ordered pairs of events. For a Relation _R_ and two values _a_ and _b_ in the value domain of _R_, _a_ _R_ _b_ is shorthand for saying the ordered pair (_a_, _b_) is a member of _R_. A Relation is the least Relation with respect to some conditions when it is the smallest Relation that satisfies those conditions.
+ The Set type is used to explain a collection of unordered elements for use in the memory model. It is distinct from the ECMAScript collection type of the same name. To disambiguate, instances of the ECMAScript collection are consistently referred to as “Set objects” within this specification. Values of the Set type are simple collections of elements, where no element appears more than once. Elements may be added to and removed from Sets. Sets may be unioned, intersected, or subtracted from each other.
+ The Relation type is used to explain constraints on Sets. Values of the Relation type are Sets of ordered pairs of values from its value domain. For example, a Relation on Memory events is a set of ordered pairs of Memory events. For a Relation _R_ and two values _a_ and _b_ in the value domain of _R_, _a_ _R_ _b_ is shorthand for saying the ordered pair (_a_, _b_) is a member of _R_. A Relation is the least Relation with respect to some conditions when it is the smallest Relation that satisfies those conditions.
A strict partial order is a Relation value _R_ that satisfies the following.
-
@@ -4058,17 +4276,19 @@
The Completion Record Specification Type
Completion Records have the fields defined in
-
-
- Field Name
-
-
- Value
-
-
- Meaning
-
-
+
+
+
+ Field Name
+
+
+ Value
+
+
+ Meaning
+
+
+
[[Type]]
@@ -4124,6 +4344,8 @@
): a normal completion
+ - skip return checks
+ - true
1. Return Completion Record { [[Type]]: ~normal~, [[Value]]: _value_, [[Target]]: ~empty~ }.
@@ -4143,6 +4365,19 @@
+
+
+ ReturnCompletion (
+ _value_: an ECMAScript language value,
+ ): a return completion
+
+
+
+
+ 1. Return Completion Record { [[Type]]: ~return~, [[Value]]: _value_, [[Target]]: ~empty~ }.
+
+
+
UpdateEmpty (
@@ -4163,15 +4398,17 @@
The Reference Record Specification Type
The Reference Record type is used to explain the behaviour of such operators as `delete`, `typeof`, the assignment operators, the `super` keyword and other language features. For example, the left-hand operand of an assignment is expected to produce a Reference Record.
- A Reference Record is a resolved name or property binding; its fields are defined by
+ A Reference Record is a resolved name or (possibly not-yet-resolved) property binding; its fields are defined by
-
- Field Name
- Value
- Meaning
-
+
+
+ Field Name
+ Value
+ Meaning
+
+
[[Base]]
an ECMAScript language value, an Environment Record, or ~unresolvable~
@@ -4179,8 +4416,8 @@ The Reference Record Specification Type
[[ReferencedName]]
- a String, a Symbol, or a Private Name
- The name of the binding. Always a String if [[Base]] value is an Environment Record.
+ an ECMAScript language value or a Private Name
+ The name of the binding. Always a String if [[Base]] value is an Environment Record. Otherwise, may be an ECMAScript language value other than a String or a Symbol until ToPropertyKey is performed.
[[Strict]]
@@ -4200,76 +4437,81 @@ The Reference Record Specification Type
IsPropertyReference (
- _V_: a Reference Record,
+ _refRecord_: a Reference Record,
): a Boolean
- 1. If _V_.[[Base]] is ~unresolvable~, return *false*.
- 1. If _V_.[[Base]] is an Environment Record, return *false*; otherwise return *true*.
+ 1. If _refRecord_.[[Base]] is ~unresolvable~, return *false*.
+ 1. If _refRecord_.[[Base]] is an Environment Record, return *false*.
+ 1. Return *true*.
IsUnresolvableReference (
- _V_: a Reference Record,
+ _refRecord_: a Reference Record,
): a Boolean
- 1. If _V_.[[Base]] is ~unresolvable~, return *true*; otherwise return *false*.
+ 1. If _refRecord_.[[Base]] is ~unresolvable~, return *true*.
+ 1. Return *false*.
IsSuperReference (
- _V_: a Reference Record,
+ _refRecord_: a Reference Record,
): a Boolean
- 1. If _V_.[[ThisValue]] is not ~empty~, return *true*; otherwise return *false*.
+ 1. If _refRecord_.[[ThisValue]] is ~empty~, return *false*.
+ 1. Return *true*.
IsPrivateReference (
- _V_: a Reference Record,
+ _refRecord_: a Reference Record,
): a Boolean
- 1. If _V_.[[ReferencedName]] is a Private Name, return *true*; otherwise return *false*.
+ 1. If _refRecord_.[[ReferencedName]] is a Private Name, return *true*.
+ 1. Return *false*.
GetValue (
- _V_: a Reference Record or an ECMAScript language value,
+ _refRecord_: a Reference Record or an ECMAScript language value,
): either a normal completion containing an ECMAScript language value or an abrupt completion
- 1. If _V_ is not a Reference Record, return _V_.
- 1. If IsUnresolvableReference(_V_) is *true*, throw a *ReferenceError* exception.
- 1. If IsPropertyReference(_V_) is *true*, then
- 1. [id="step-getvalue-toobject"] Let _baseObj_ be ? ToObject(_V_.[[Base]]).
- 1. If IsPrivateReference(_V_) is *true*, then
- 1. Return ? PrivateGet(_baseObj_, _V_.[[ReferencedName]]).
- 1. Return ? _baseObj_.[[Get]] (_V_.[[ReferencedName]], GetThisValue(_V_)).
- 1. Else,
- 1. Let _base_ be _V_.[[Base]].
- 1. Assert: _base_ is an Environment Record.
- 1. Return ? _base_.GetBindingValue (_V_.[[ReferencedName]], _V_.[[Strict]]) (see _baseObj_.[[Get]](_refRecord_.[[ReferencedName]], GetThisValue(_refRecord_)) .
+ 1. Let _base_ be _refRecord_.[[Base]].
+ 1. Assert: _base_ is an Environment Record.
+ 1. Return ? _base_.GetBindingValue(_refRecord_.[[ReferencedName]], _refRecord_.[[Strict]]) (see
The object that may be created in step
@@ -4279,30 +4521,31 @@
PutValue (
- _V_: a Reference Record or an ECMAScript language value,
- _W_: an ECMAScript language value,
+ _refRecord_: a Reference Record or an ECMAScript language value,
+ _value_: an ECMAScript language value,
): either a normal completion containing ~unused~ or an abrupt completion
- 1. If _V_ is not a Reference Record, throw a *ReferenceError* exception.
- 1. If IsUnresolvableReference(_V_) is *true*, then
- 1. If _V_.[[Strict]] is *true*, throw a *ReferenceError* exception.
+ 1. If _refRecord_ is not a Reference Record, throw a *ReferenceError* exception.
+ 1. If IsUnresolvableReference(_refRecord_) is *true*, then
+ 1. If _refRecord_.[[Strict]] is *true*, throw a *ReferenceError* exception.
1. Let _globalObj_ be GetGlobalObject().
- 1. Perform ? Set(_globalObj_, _V_.[[ReferencedName]], _W_, *false*).
+ 1. Perform ? Set(_globalObj_, _refRecord_.[[ReferencedName]], _value_, *false*).
1. Return ~unused~.
- 1. If IsPropertyReference(_V_) is *true*, then
- 1. [id="step-putvalue-toobject"] Let _baseObj_ be ? ToObject(_V_.[[Base]]).
- 1. If IsPrivateReference(_V_) is *true*, then
- 1. Return ? PrivateSet(_baseObj_, _V_.[[ReferencedName]], _W_).
- 1. Let _succeeded_ be ? _baseObj_.[[Set]] (_V_.[[ReferencedName]], _W_, GetThisValue(_V_)).
- 1. If _succeeded_ is *false* and _V_.[[Strict]] is *true*, throw a *TypeError* exception.
+ 1. If IsPropertyReference(_refRecord_) is *true*, then
+ 1. [id="step-putvalue-toobject"] Let _baseObj_ be ? ToObject(_refRecord_.[[Base]]).
+ 1. If IsPrivateReference(_refRecord_) is *true*, then
+ 1. Return ? PrivateSet(_baseObj_, _refRecord_.[[ReferencedName]], _value_).
+ 1. If _refRecord_.[[ReferencedName]] is not a property key, then
+ 1. Set _refRecord_.[[ReferencedName]] to ? ToPropertyKey(_refRecord_.[[ReferencedName]]).
+ 1. Let _succeeded_ be ? _baseObj_.[[Set]](_refRecord_.[[ReferencedName]], _value_, GetThisValue(_refRecord_)) .
+ 1. If _succeeded_ is *false* and _refRecord_.[[Strict]] is *true*, throw a *TypeError* exception.
1. Return ~unused~.
- 1. Else,
- 1. Let _base_ be _V_.[[Base]].
- 1. Assert: _base_ is an Environment Record.
- 1. Return ? _base_.SetMutableBinding (_V_.[[ReferencedName]], _W_, _V_.[[Strict]]) (see _base_.SetMutableBinding(_refRecord_.[[ReferencedName]], _value_, _refRecord_.[[Strict]]) (see
The object that may be created in step
@@ -4312,31 +4555,32 @@
GetThisValue (
- _V_: a Reference Record,
+ _refRecord_: a Reference Record,
): an ECMAScript language value
- 1. Assert: IsPropertyReference(_V_) is *true*.
- 1. If IsSuperReference(_V_) is *true*, return _V_.[[ThisValue]]; otherwise return _V_.[[Base]].
+ 1. Assert: IsPropertyReference(_refRecord_) is *true*.
+ 1. If IsSuperReference(_refRecord_) is *true*, return _refRecord_.[[ThisValue]].
+ 1. Return _refRecord_.[[Base]].
InitializeReferencedBinding (
- _V_: a Reference Record,
- _W_: an ECMAScript language value,
+ _refRecord_: a Reference Record,
+ _value_: an ECMAScript language value,
): either a normal completion containing ~unused~ or an abrupt completion
- 1. Assert: IsUnresolvableReference(_V_) is *false*.
- 1. Let _base_ be _V_.[[Base]].
+ 1. Assert: IsUnresolvableReference(_refRecord_) is *false*.
+ 1. Let _base_ be _refRecord_.[[Base]].
1. Assert: _base_ is an Environment Record.
- 1. Return ? _base_.InitializeBinding(_V_.[[ReferencedName]], _W_).
+ 1. Return ? _base_.InitializeBinding(_refRecord_.[[ReferencedName]], _value_).
@@ -4350,9 +4594,9 @@
- 1. Let _privEnv_ be the running execution context's PrivateEnvironment.
- 1. Assert: _privEnv_ is not *null*.
- 1. Let _privateName_ be ResolvePrivateIdentifier(_privEnv_, _privateIdentifier_).
+ 1. Let _privateEnv_ be the running execution context's PrivateEnvironment.
+ 1. Assert: _privateEnv_ is not *null*.
+ 1. Let _privateName_ be ResolvePrivateIdentifier(_privateEnv_, _privateIdentifier_).
1. Return the Reference Record { [[Base]]: _baseValue_, [[ReferencedName]]: _privateName_, [[Strict]]: *true*, [[ThisValue]]: ~empty~ }.
@@ -4361,21 +4605,20 @@
The Property Descriptor Specification Type
The Property Descriptor type is used to explain the manipulation and reification of Object property attributes. A Property Descriptor is a Record with zero or more fields, where each field's name is an attribute name and its value is a corresponding attribute value as specified in
- Property Descriptor values may be further classified as data Property Descriptors and accessor Property Descriptors based upon the existence or use of certain fields. A data Property Descriptor is one that includes any fields named either [[Value]] or [[Writable]]. An accessor Property Descriptor is one that includes any fields named either [[Get]] or [[Set]]. Any Property Descriptor may have fields named [[Enumerable]] and [[Configurable]]. A Property Descriptor value may not be both a data Property Descriptor and an accessor Property Descriptor; however, it may be neither (in which case it is a generic Property Descriptor). A fully populated Property Descriptor is one that is either an accessor Property Descriptor or a data Property Descriptor and that has all of the corresponding fields defined in
+ Property Descriptor values may be further classified as data Property Descriptors and accessor Property Descriptors based upon the existence or use of certain fields. A data Property Descriptor is one that includes any fields named either [[Value]] or [[Writable]]. An accessor Property Descriptor is one that includes any fields named either [[Getter]] or [[Setter]]. Any Property Descriptor may have fields named [[Enumerable]] and [[Configurable]]. A Property Descriptor value may not be both a data Property Descriptor and an accessor Property Descriptor; however, it may be neither (in which case it is a generic Property Descriptor). A fully populated Property Descriptor is one that is either an accessor Property Descriptor or a data Property Descriptor and that has all of the corresponding fields defined in
The following abstract operations are used in this specification to operate upon Property Descriptor values:
IsAccessorDescriptor (
- _Desc_: a Property Descriptor or *undefined*,
+ _propertyDesc_: a Property Descriptor,
): a Boolean
- 1. If _Desc_ is *undefined*, return *false*.
- 1. If _Desc_ has a [[Get]] field, return *true*.
- 1. If _Desc_ has a [[Set]] field, return *true*.
+ 1. If _propertyDesc_ has a [[Getter]] field, return *true*.
+ 1. If _propertyDesc_ has a [[Setter]] field, return *true*.
1. Return *false*.
@@ -4383,15 +4626,14 @@
IsDataDescriptor (
- _Desc_: a Property Descriptor or *undefined*,
+ _propertyDesc_: a Property Descriptor,
): a Boolean
- 1. If _Desc_ is *undefined*, return *false*.
- 1. If _Desc_ has a [[Value]] field, return *true*.
- 1. If _Desc_ has a [[Writable]] field, return *true*.
+ 1. If _propertyDesc_ has a [[Value]] field, return *true*.
+ 1. If _propertyDesc_ has a [[Writable]] field, return *true*.
1. Return *false*.
@@ -4399,15 +4641,14 @@
IsGenericDescriptor (
- _Desc_: a Property Descriptor or *undefined*,
+ _propertyDesc_: a Property Descriptor,
): a Boolean
- 1. If _Desc_ is *undefined*, return *false*.
- 1. If IsAccessorDescriptor(_Desc_) is *true*, return *false*.
- 1. If IsDataDescriptor(_Desc_) is *true*, return *false*.
+ 1. If IsAccessorDescriptor(_propertyDesc_) is *true*, return *false*.
+ 1. If IsDataDescriptor(_propertyDesc_) is *true*, return *false*.
1. Return *true*.
@@ -4415,27 +4656,27 @@
FromPropertyDescriptor (
- _Desc_: a Property Descriptor or *undefined*,
+ _propertyDesc_: a Property Descriptor or *undefined*,
): an Object or *undefined*
- 1. If _Desc_ is *undefined*, return *undefined*.
+ 1. If _propertyDesc_ is *undefined*, return *undefined*.
1. Let _obj_ be OrdinaryObjectCreate(%Object.prototype%).
1. Assert: _obj_ is an extensible ordinary object with no own properties.
- 1. If _Desc_ has a [[Value]] field, then
- 1. Perform ! CreateDataPropertyOrThrow(_obj_, *"value"*, _Desc_.[[Value]]).
- 1. If _Desc_ has a [[Writable]] field, then
- 1. Perform ! CreateDataPropertyOrThrow(_obj_, *"writable"*, _Desc_.[[Writable]]).
- 1. If _Desc_ has a [[Get]] field, then
- 1. Perform ! CreateDataPropertyOrThrow(_obj_, *"get"*, _Desc_.[[Get]]).
- 1. If _Desc_ has a [[Set]] field, then
- 1. Perform ! CreateDataPropertyOrThrow(_obj_, *"set"*, _Desc_.[[Set]]).
- 1. If _Desc_ has an [[Enumerable]] field, then
- 1. Perform ! CreateDataPropertyOrThrow(_obj_, *"enumerable"*, _Desc_.[[Enumerable]]).
- 1. If _Desc_ has a [[Configurable]] field, then
- 1. Perform ! CreateDataPropertyOrThrow(_obj_, *"configurable"*, _Desc_.[[Configurable]]).
+ 1. If _propertyDesc_ has a [[Value]] field, then
+ 1. Perform ! CreateDataPropertyOrThrow(_obj_, *"value"*, _propertyDesc_.[[Value]]).
+ 1. If _propertyDesc_ has a [[Writable]] field, then
+ 1. Perform ! CreateDataPropertyOrThrow(_obj_, *"writable"*, _propertyDesc_.[[Writable]]).
+ 1. If _propertyDesc_ has a [[Getter]] field, then
+ 1. Perform ! CreateDataPropertyOrThrow(_obj_, *"get"*, _propertyDesc_.[[Getter]]).
+ 1. If _propertyDesc_ has a [[Setter]] field, then
+ 1. Perform ! CreateDataPropertyOrThrow(_obj_, *"set"*, _propertyDesc_.[[Setter]]).
+ 1. If _propertyDesc_ has an [[Enumerable]] field, then
+ 1. Perform ! CreateDataPropertyOrThrow(_obj_, *"enumerable"*, _propertyDesc_.[[Enumerable]]).
+ 1. If _propertyDesc_ has a [[Configurable]] field, then
+ 1. Perform ! CreateDataPropertyOrThrow(_obj_, *"configurable"*, _propertyDesc_.[[Configurable]]).
1. Return _obj_.
@@ -4443,64 +4684,64 @@
ToPropertyDescriptor (
- _Obj_: an ECMAScript language value,
+ _obj_: an ECMAScript language value,
): either a normal completion containing a Property Descriptor or a throw completion
- 1. If _Obj_ is not an Object, throw a *TypeError* exception.
- 1. Let _desc_ be a new Property Descriptor that initially has no fields.
- 1. Let _hasEnumerable_ be ? HasProperty(_Obj_, *"enumerable"*).
+ 1. If _obj_ is not an Object, throw a *TypeError* exception.
+ 1. Let _propertyDesc_ be a new Property Descriptor that initially has no fields.
+ 1. Let _hasEnumerable_ be ? HasProperty(_obj_, *"enumerable"*).
1. If _hasEnumerable_ is *true*, then
- 1. Let _enumerable_ be ToBoolean(? Get(_Obj_, *"enumerable"*)).
- 1. Set _desc_.[[Enumerable]] to _enumerable_.
- 1. Let _hasConfigurable_ be ? HasProperty(_Obj_, *"configurable"*).
+ 1. Let _enumerable_ be ToBoolean(? Get(_obj_, *"enumerable"*)).
+ 1. Set _propertyDesc_.[[Enumerable]] to _enumerable_.
+ 1. Let _hasConfigurable_ be ? HasProperty(_obj_, *"configurable"*).
1. If _hasConfigurable_ is *true*, then
- 1. Let _configurable_ be ToBoolean(? Get(_Obj_, *"configurable"*)).
- 1. Set _desc_.[[Configurable]] to _configurable_.
- 1. Let _hasValue_ be ? HasProperty(_Obj_, *"value"*).
+ 1. Let _configurable_ be ToBoolean(? Get(_obj_, *"configurable"*)).
+ 1. Set _propertyDesc_.[[Configurable]] to _configurable_.
+ 1. Let _hasValue_ be ? HasProperty(_obj_, *"value"*).
1. If _hasValue_ is *true*, then
- 1. Let _value_ be ? Get(_Obj_, *"value"*).
- 1. Set _desc_.[[Value]] to _value_.
- 1. Let _hasWritable_ be ? HasProperty(_Obj_, *"writable"*).
+ 1. Let _value_ be ? Get(_obj_, *"value"*).
+ 1. Set _propertyDesc_.[[Value]] to _value_.
+ 1. Let _hasWritable_ be ? HasProperty(_obj_, *"writable"*).
1. If _hasWritable_ is *true*, then
- 1. Let _writable_ be ToBoolean(? Get(_Obj_, *"writable"*)).
- 1. Set _desc_.[[Writable]] to _writable_.
- 1. Let _hasGet_ be ? HasProperty(_Obj_, *"get"*).
+ 1. Let _writable_ be ToBoolean(? Get(_obj_, *"writable"*)).
+ 1. Set _propertyDesc_.[[Writable]] to _writable_.
+ 1. Let _hasGet_ be ? HasProperty(_obj_, *"get"*).
1. If _hasGet_ is *true*, then
- 1. Let _getter_ be ? Get(_Obj_, *"get"*).
+ 1. Let _getter_ be ? Get(_obj_, *"get"*).
1. If IsCallable(_getter_) is *false* and _getter_ is not *undefined*, throw a *TypeError* exception.
- 1. Set _desc_.[[Get]] to _getter_.
- 1. Let _hasSet_ be ? HasProperty(_Obj_, *"set"*).
+ 1. Set _propertyDesc_.[[Getter]] to _getter_.
+ 1. Let _hasSet_ be ? HasProperty(_obj_, *"set"*).
1. If _hasSet_ is *true*, then
- 1. Let _setter_ be ? Get(_Obj_, *"set"*).
+ 1. Let _setter_ be ? Get(_obj_, *"set"*).
1. If IsCallable(_setter_) is *false* and _setter_ is not *undefined*, throw a *TypeError* exception.
- 1. Set _desc_.[[Set]] to _setter_.
- 1. If _desc_ has a [[Get]] field or _desc_ has a [[Set]] field, then
- 1. If _desc_ has a [[Value]] field or _desc_ has a [[Writable]] field, throw a *TypeError* exception.
- 1. Return _desc_.
+ 1. Set _propertyDesc_.[[Setter]] to _setter_.
+ 1. If _propertyDesc_ has a [[Getter]] field or _propertyDesc_ has a [[Setter]] field, then
+ 1. If _propertyDesc_ has a [[Value]] field or _propertyDesc_ has a [[Writable]] field, throw a *TypeError* exception.
+ 1. Return _propertyDesc_.
CompletePropertyDescriptor (
- _Desc_: a Property Descriptor,
+ _propertyDesc_: a Property Descriptor,
): ~unused~
- 1. Let _like_ be the Record { [[Value]]: *undefined*, [[Writable]]: *false*, [[Get]]: *undefined*, [[Set]]: *undefined*, [[Enumerable]]: *false*, [[Configurable]]: *false* }.
- 1. If IsGenericDescriptor(_Desc_) is *true* or IsDataDescriptor(_Desc_) is *true*, then
- 1. If _Desc_ does not have a [[Value]] field, set _Desc_.[[Value]] to _like_.[[Value]].
- 1. If _Desc_ does not have a [[Writable]] field, set _Desc_.[[Writable]] to _like_.[[Writable]].
+ 1. Let _like_ be the Record { [[Value]]: *undefined*, [[Writable]]: *false*, [[Getter]]: *undefined*, [[Setter]]: *undefined*, [[Enumerable]]: *false*, [[Configurable]]: *false* }.
+ 1. If IsGenericDescriptor(_propertyDesc_) is *true* or IsDataDescriptor(_propertyDesc_) is *true*, then
+ 1. If _propertyDesc_ does not have a [[Value]] field, set _propertyDesc_.[[Value]] to _like_.[[Value]].
+ 1. If _propertyDesc_ does not have a [[Writable]] field, set _propertyDesc_.[[Writable]] to _like_.[[Writable]].
1. Else,
- 1. If _Desc_ does not have a [[Get]] field, set _Desc_.[[Get]] to _like_.[[Get]].
- 1. If _Desc_ does not have a [[Set]] field, set _Desc_.[[Set]] to _like_.[[Set]].
- 1. If _Desc_ does not have an [[Enumerable]] field, set _Desc_.[[Enumerable]] to _like_.[[Enumerable]].
- 1. If _Desc_ does not have a [[Configurable]] field, set _Desc_.[[Configurable]] to _like_.[[Configurable]].
+ 1. If _propertyDesc_ does not have a [[Getter]] field, set _propertyDesc_.[[Getter]] to _like_.[[Getter]].
+ 1. If _propertyDesc_ does not have a [[Setter]] field, set _propertyDesc_.[[Setter]] to _like_.[[Setter]].
+ 1. If _propertyDesc_ does not have an [[Enumerable]] field, set _propertyDesc_.[[Enumerable]] to _like_.[[Enumerable]].
+ 1. If _propertyDesc_ does not have a [[Configurable]] field, set _propertyDesc_.[[Configurable]] to _like_.[[Configurable]].
1. Return ~unused~.
@@ -4514,25 +4755,25 @@ The Environment Record Specification Type
The Abstract Closure Specification Type
The Abstract Closure specification type is used to refer to algorithm steps together with a collection of values. Abstract Closures are meta-values and are invoked using function application style such as _closure_(_arg1_, _arg2_). Like abstract operations, invocations perform the algorithm steps described by the Abstract Closure.
- In algorithm steps that create an Abstract Closure, values are captured with the verb "capture" followed by a list of aliases. When an Abstract Closure is created, it captures the value that is associated with each alias at that time. In steps that specify the algorithm to be performed when an Abstract Closure is called, each captured value is referred to by the alias that was used to capture the value.
+ In algorithm steps that create an Abstract Closure, values are captured with the verb “capture” followed by a list of aliases. When an Abstract Closure is created, it captures the value that is associated with each alias at that time. In steps that specify the algorithm to be performed when an Abstract Closure is called, each captured value is referred to by the alias that was used to capture the value.
If an Abstract Closure returns a Completion Record, that Completion Record must be either a normal completion or a throw completion.
Abstract Closures are created inline as part of other algorithms, shown in the following example.
1. Let _addend_ be 41.
1. Let _closure_ be a new Abstract Closure with parameters (_x_) that captures _addend_ and performs the following steps when called:
1. Return _x_ + _addend_.
- 1. Let _val_ be _closure_(1).
- 1. Assert: _val_ is 42.
+ 1. Let _value_ be _closure_(1).
+ 1. Assert: _value_ is 42.
Data Blocks
The Data Block specification type is used to describe a distinct and mutable sequence of byte-sized (8 bit) numeric values. A byte value is an integer in the inclusive interval from 0 to 255. A Data Block value is created with a fixed number of bytes that each have the initial value 0.
- For notational convenience within this specification, an array-like syntax can be used to access the individual bytes of a Data Block value. This notation presents a Data Block value as a 0-origined integer-indexed sequence of bytes. For example, if _db_ is a 5 byte Data Block value then _db_[2] can be used to access its 3rd byte.
+ For notational convenience within this specification, an array-like syntax can be used to access the individual bytes of a Data Block value. This notation presents a Data Block value as a 0-based integer-indexed sequence of bytes. For example, if _dataBlock_ is a 5 byte Data Block value then _dataBlock_[2] can be used to access its 3rd byte.
A data block that resides in memory that can be referenced from multiple agents concurrently is designated a Shared Data Block. A Shared Data Block has an identity (for the purposes of equality testing Shared Data Block values) that is address-free: it is tied not to the virtual addresses the block is mapped to in any process, but to the set of locations in memory that the block represents. Two data blocks are equal only if the sets of the locations they contain are equal; otherwise, they are not equal and the intersection of the sets of locations they contain is empty. Finally, Shared Data Blocks can be distinguished from Data Blocks.
The semantics of Shared Data Blocks is defined using Shared Data Block events by the memory model. Abstract operations below introduce Shared Data Block events and act as the interface between evaluation semantics and the event semantics of the memory model. The events form a candidate execution, on which the memory model acts as a filter. Please consult the memory model for full semantics.
- Shared Data Block events are modeled by Records, defined in the memory model.
+ Shared Data Block events are modelled by Records, defined in the memory model.
The following abstract operations are used in this specification to operate upon Data Block values:
@@ -4545,9 +4786,9 @@
1. If _size_ > 253 - 1, throw a *RangeError* exception.
- 1. Let _db_ be a new Data Block value consisting of _size_ bytes. If it is impossible to create such a Data Block, throw a *RangeError* exception.
- 1. Set all of the bytes of _db_ to 0.
- 1. Return _db_.
+ 1. Let _dataBlock_ be a new Data Block value consisting of _size_ bytes. If it is impossible to create such a Data Block, throw a *RangeError* exception.
+ 1. Set all of the bytes of _dataBlock_ to 0.
+ 1. Return _dataBlock_.
@@ -4560,13 +4801,14 @@
- 1. Let _db_ be a new Shared Data Block value consisting of _size_ bytes. If it is impossible to create such a Shared Data Block, throw a *RangeError* exception.
- 1. Let _execution_ be the [[CandidateExecution]] field of the surrounding agent's Agent Record.
+ 1. Let _dataBlock_ be a new Shared Data Block value consisting of _size_ bytes. If it is impossible to create such a Shared Data Block, throw a *RangeError* exception.
+ 1. Let _agentRecord_ be the Agent Record of the surrounding agent.
+ 1. Let _execution_ be _agentRecord_.[[CandidateExecution]].
1. Let _eventsRecord_ be the Agent Events Record of _execution_.[[EventsRecords]] whose [[AgentSignifier]] is AgentSignifier().
1. Let _zero_ be « 0 ».
- 1. For each index _i_ of _db_, do
- 1. Append WriteSharedMemory { [[Order]]: ~init~, [[NoTear]]: *true*, [[Block]]: _db_, [[ByteIndex]]: _i_, [[ElementSize]]: 1, [[Payload]]: _zero_ } to _eventsRecord_.[[EventList]].
- 1. Return _db_.
+ 1. For each index _index_ of _dataBlock_, do
+ 1. Append WriteSharedMemory { [[Order]]: ~init~, [[NoTear]]: *true*, [[Block]]: _dataBlock_, [[ByteIndex]]: _index_, [[ElementSize]]: 1, [[Payload]]: _zero_ } to _eventsRecord_.[[EventList]].
+ 1. Return _dataBlock_.
@@ -4590,7 +4832,8 @@
1. Assert: _toIndex_ + _count_ ≤ _toSize_.
1. Repeat, while _count_ > 0,
1. If _fromBlock_ is a Shared Data Block, then
- 1. Let _execution_ be the [[CandidateExecution]] field of the surrounding agent's Agent Record.
+ 1. Let _agentRecord_ be the Agent Record of the surrounding agent.
+ 1. Let _execution_ be _agentRecord_.[[CandidateExecution]].
1. Let _eventsRecord_ be the Agent Events Record of _execution_.[[EventsRecords]] whose [[AgentSignifier]] is AgentSignifier().
1. Let _bytes_ be a List whose sole element is a nondeterministically chosen byte value.
1. NOTE: In implementations, _bytes_ is the result of a non-atomic read instruction on the underlying hardware. The nondeterminism is a semantic prescription of the memory model to describe observable behaviour of hardware with weak consistency.
@@ -4615,23 +4858,25 @@
The PrivateElement Specification Type
The PrivateElement type is a Record used in the specification of private class fields, methods, and accessors. Although Property Descriptors are not used for private elements, private fields behave similarly to non-configurable, non-enumerable, writable data properties, private methods behave similarly to non-configurable, non-enumerable, non-writable data properties, and private accessors behave similarly to non-configurable, non-enumerable accessor properties.
- Values of the PrivateElement type are Record values whose fields are defined by
+ Values of the PrivateElement type are Records whose fields are defined by
-
-
- Field Name
-
-
- Values of the [[Kind]] field for which it is present
-
-
- Value
-
-
- Meaning
-
-
+
+
+
+ Field Name
+
+
+ Values of the [[Kind]] field for which it is present
+
+
+ Value
+
+
+ Meaning
+
+
+
[[Key]]
@@ -4676,7 +4921,7 @@ The PrivateElement Specification Type
- [[Get]]
+ [[Getter]]
~accessor~
@@ -4690,7 +4935,7 @@ The PrivateElement Specification Type
- [[Set]]
+ [[Setter]]
~accessor~
@@ -4709,20 +4954,22 @@ The PrivateElement Specification Type
The ClassFieldDefinition Record Specification Type
The ClassFieldDefinition type is a Record used in the specification of class fields.
- Values of the ClassFieldDefinition type are Record values whose fields are defined by
+ Values of the ClassFieldDefinition type are Records whose fields are defined by
-
-
- Field Name
-
-
- Value
-
-
- Meaning
-
-
+
+
+
+ Field Name
+
+
+ Value
+
+
+ Meaning
+
+
+
[[Name]]
@@ -4751,26 +4998,28 @@ The ClassFieldDefinition Record Specification Type
Private Names
- The Private Name specification type is used to describe a globally unique value (one which differs from any other Private Name, even if they are otherwise indistinguishable) which represents the key of a private class element (field, method, or accessor). Each Private Name has an associated immutable [[Description]] which is a String value. A Private Name may be installed on any ECMAScript object with PrivateFieldAdd or PrivateMethodOrAccessorAdd, and then read or written using PrivateGet and PrivateSet.
+ The Private Name specification type is used to describe a globally unique value (one which differs from any other Private Name, even if they are otherwise indistinguishable) which represents the key of a private class element (field, method, or accessor). Each Private Name has an immutable [[Description]] internal slot which is a String. A Private Name may be installed on any ECMAScript object with PrivateFieldAdd or PrivateMethodOrAccessorAdd, and then read or written using PrivateGet and PrivateSet.
The ClassStaticBlockDefinition Record Specification Type
- A ClassStaticBlockDefinition Record is a Record value used to encapsulate the executable code for a class static initialization block.
+ A ClassStaticBlockDefinition Record is a Record used to encapsulate the executable code for a class static initialization block.
ClassStaticBlockDefinition Records have the fields listed in
-
-
- Field Name
-
-
- Value
-
-
- Meaning
-
-
+
+
+
+ Field Name
+
+
+ Value
+
+
+ Meaning
+
+
+
[[BodyFunction]]
@@ -4810,8 +5059,8 @@
1. If _input_ is an Object, then
- 1. Let _exoticToPrim_ be ? GetMethod(_input_, @@toPrimitive).
- 1. If _exoticToPrim_ is not *undefined*, then
+ 1. Let _exoticToPrimitive_ be ? GetMethod(_input_, %Symbol.toPrimitive%).
+ 1. If _exoticToPrimitive_ is not *undefined*, then
1. If _preferredType_ is not present, then
1. Let _hint_ be *"default"*.
1. Else if _preferredType_ is ~string~, then
@@ -4819,21 +5068,21 @@
1. Else,
1. Assert: _preferredType_ is ~number~.
1. Let _hint_ be *"number"*.
- 1. Let _result_ be ? Call(_exoticToPrim_, _input_, « _hint_ »).
+ 1. Let _result_ be ? Call(_exoticToPrimitive_, _input_, « _hint_ »).
1. If _result_ is not an Object, return _result_.
1. Throw a *TypeError* exception.
- 1. If _preferredType_ is not present, let _preferredType_ be ~number~.
+ 1. If _preferredType_ is not present, set _preferredType_ to ~number~.
1. Return ? OrdinaryToPrimitive(_input_, _preferredType_).
1. Return _input_.
- When ToPrimitive is called without a hint, then it generally behaves as if the hint were ~number~. However, objects may over-ride this behaviour by defining a @@toPrimitive method. Of the objects defined in this specification only Dates (see
+ When ToPrimitive is called without a hint, then it generally behaves as if the hint were ~number~. However, objects may over-ride this behaviour by defining a %Symbol.toPrimitive% method. Of the objects defined in this specification only Dates (see
OrdinaryToPrimitive (
- _O_: an Object,
+ _obj_: an Object,
_hint_: ~string~ or ~number~,
): either a normal completion containing an ECMAScript language value or a throw completion
@@ -4845,29 +5094,30 @@
1. Else,
1. Let _methodNames_ be « *"valueOf"*, *"toString"* ».
1. For each element _name_ of _methodNames_, do
- 1. Let _method_ be ? Get(_O_, _name_).
+ 1. Let _method_ be ? Get(_obj_, _name_).
1. If IsCallable(_method_) is *true*, then
- 1. Let _result_ be ? Call(_method_, _O_).
+ 1. Let _result_ be ? Call(_method_, _obj_).
1. If _result_ is not an Object, return _result_.
1. Throw a *TypeError* exception.
-
+
ToBoolean (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): a Boolean
- description
- - It converts _argument_ to a value of type Boolean.
+ - It converts _arg_ to a value of type Boolean.
- 1. If _argument_ is a Boolean, return _argument_.
- 1. If _argument_ is one of *undefined*, *null*, *+0*𝔽, *-0*𝔽, *NaN*, *0*ℤ, or the empty String, return *false*.
- 1. [id="step-to-boolean-web-compat-insertion-point"] NOTE: This step is replaced in section
@@ -4875,41 +5125,41 @@
ToNumeric (
- _value_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing either a Number or a BigInt, or a throw completion
- description
- - It returns _value_ converted to a Number or a BigInt.
+ - It returns _arg_ converted to a Number or a BigInt.
- 1. Let _primValue_ be ? ToPrimitive(_value_, ~number~).
- 1. If _primValue_ is a BigInt, return _primValue_.
- 1. Return ? ToNumber(_primValue_) .
+ 1. Let _primitiveValue_ be ? ToPrimitive(_arg_, ~number~).
+ 1. If _primitiveValue_ is a BigInt, return _primitiveValue_.
+ 1. Return ? ToNumber(_primitiveValue_) .
ToNumber (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing a Number or a throw completion
- description
- - It converts _argument_ to a value of type Number.
+ - It converts _arg_ to a value of type Number.
- 1. If _argument_ is a Number, return _argument_.
- 1. If _argument_ is either a Symbol or a BigInt, throw a *TypeError* exception.
- 1. If _argument_ is *undefined*, return *NaN*.
- 1. If _argument_ is either *null* or *false*, return *+0*𝔽.
- 1. If _argument_ is *true*, return *1*𝔽.
- 1. If _argument_ is a String, return StringToNumber(_argument_).
- 1. Assert: _argument_ is an Object.
- 1. Let _primValue_ be ? ToPrimitive(_argument_, ~number~).
- 1. Assert: _primValue_ is not an Object.
- 1. Return ? ToNumber(_primValue_).
+ 1. If _arg_ is a Number, return _arg_.
+ 1. If _arg_ is either a Symbol or a BigInt, throw a *TypeError* exception.
+ 1. If _arg_ is *undefined*, return *NaN*.
+ 1. If _arg_ is either *null* or *false*, return *+0*𝔽.
+ 1. If _arg_ is *true*, return *1*𝔽.
+ 1. If _arg_ is a String, return StringToNumber(_arg_).
+ 1. Assert: _arg_ is an Object.
+ 1. Let _primitiveValue_ be ? ToPrimitive(_arg_, ~number~).
+ 1. Assert: _primitiveValue_ is not an Object.
+ 1. Return ? ToNumber(_primitiveValue_).
@@ -4974,13 +5224,13 @@ Syntax
StringToNumber (
- _str_: a String,
+ _string_: a String,
): a Number
- 1. Let _literal_ be ParseText(_str_, |StringNumericLiteral|).
+ 1. Let _literal_ be ParseText(_string_, |StringNumericLiteral|).
1. If _literal_ is a List of errors, return *NaN*.
1. Return the StringNumericValue of _literal_.
@@ -5024,20 +5274,20 @@ Runtime Semantics: StringNumericValue ( ): a Number
1. Else,
1. Let _b_ be 0.
1. Let _n_ be 0.
- 1. If |ExponentPart| is present, let _e_ be the MV of |ExponentPart|. Otherwise, let _e_ be 0.
+ 1. If |ExponentPart| is present, let _e_ be the MV of |ExponentPart|; else let _e_ be 0.
1. Return RoundMVResult((_a_ + (_b_ × 10-_n_)) × 10_e_).
StrUnsignedDecimalLiteral ::: `.` DecimalDigits ExponentPart?
1. Let _b_ be the MV of |DecimalDigits|.
- 1. If |ExponentPart| is present, let _e_ be the MV of |ExponentPart|. Otherwise, let _e_ be 0.
+ 1. If |ExponentPart| is present, let _e_ be the MV of |ExponentPart|; else let _e_ be 0.
1. Let _n_ be the number of code points in |DecimalDigits|.
1. Return RoundMVResult(_b_ × 10_e_ - _n_).
StrUnsignedDecimalLiteral ::: DecimalDigits ExponentPart?
1. Let _a_ be the MV of |DecimalDigits|.
- 1. If |ExponentPart| is present, let _e_ be the MV of |ExponentPart|. Otherwise, let _e_ be 0.
+ 1. If |ExponentPart| is present, let _e_ be the MV of |ExponentPart|; else let _e_ be 0.
1. Return RoundMVResult(_a_ × 10_e_).
@@ -5050,7 +5300,7 @@
- description
- - It converts _n_ to a Number in an implementation-defined manner. For the purposes of this abstract operation, a digit is significant if it is not zero or there is a non-zero digit to its left and there is a non-zero digit to its right. For the purposes of this abstract operation, "the mathematical value denoted by" a representation of a mathematical value is the inverse of "the decimal representation of" a mathematical value.
+ - It converts _n_ to a Number in an implementation-defined manner. For the purposes of this abstract operation, a digit is significant if it is not zero or there is a non-zero digit to its left and there is a non-zero digit to its right. For the purposes of this abstract operation, “the mathematical value denoted by” a representation of a mathematical value is the inverse of “the decimal representation of” a mathematical value.
1. If the decimal representation of _n_ has 20 or fewer significant digits, return 𝔽(_n_).
@@ -5066,15 +5316,15 @@
ToIntegerOrInfinity (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing either an integer, +∞, or -∞, or a throw completion
- description
- - It converts _argument_ to an integer representing its Number value with fractional part truncated, or to +∞ or -∞ when that Number value is infinite.
+ - It converts _arg_ to an integer representing its Number value with fractional part truncated, or to +∞ or -∞ when that Number value is infinite.
- 1. Let _number_ be ? ToNumber(_argument_).
+ 1. Let _number_ be ? ToNumber(_arg_).
1. If _number_ is one of *NaN*, *+0*𝔽, or *-0*𝔽, return 0.
1. If _number_ is *+∞*𝔽, return +∞.
1. If _number_ is *-∞*𝔽, return -∞.
@@ -5085,181 +5335,146 @@
+
+
+ ToFixedSizeInteger (
+ _int_: an integer, +∞, or -∞,
+ _signed_: ~unsigned~ or ~signed~,
+ _bitWidth_: a positive integer,
+ ): an integer
+
+
+ - description
+ - It maps _int_ to one of 2_bitWidth_ integers in the inclusive interval from 0 to 2_bitWidth_ - 1 (if _signed_ is ~unsigned~) or -2_bitWidth_ - 1 to 2_bitWidth_ - 1 - 1 (if _signed_ is ~signed~).
+
+
+ 1. If _int_ = +∞ or _int_ = -∞, return 0.
+ 1. Let _fixedInt_ be _int_ modulo 2_bitWidth_.
+ 1. NOTE: The following step does not change the two's complement representation of _fixedInt_.
+ 1. If _signed_ is ~signed~ and _fixedInt_ ≥ 2_bitWidth_ - 1, set _fixedInt_ to _fixedInt_ - 2_bitWidth_.
+ 1. Return _fixedInt_.
+
+
+ ToFixedSizeInteger is idempotent: for any ECMAScript language value _x_, ToFixedSizeInteger(ToFixedSizeInteger(_x_, _signed_, _bitWidth_), _signed_, _bitWidth_) is the same as ToFixedSizeInteger(_x_, _signed_, _bitWidth_). In fact, because +∞ and -∞ are mapped to 0, this invariant even survives inversion of _signed_ (e.g., ToFixedSizeInteger(ToFixedSizeInteger(_x_, ~signed~, 32), ~unsigned~, 32) is the same as ToFixedSizeInteger(_x_, ~unsigned~, 32)).
+
+
+
ToInt32 (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing an integral Number or a throw completion
- description
- - It converts _argument_ to one of 232 integral Number values in the inclusive interval from 𝔽(-231) to 𝔽(231 - 1).
+ - It converts _arg_ to one of 232 integral Number values in the inclusive interval from 𝔽(-231) to 𝔽(231 - 1), excluding *-0*𝔽.
- 1. Let _number_ be ? ToNumber(_argument_).
- 1. If _number_ is not finite or _number_ is either *+0*𝔽 or *-0*𝔽, return *+0*𝔽.
- 1. Let _int_ be truncate(ℝ(_number_)).
- 1. Let _int32bit_ be _int_ modulo 232.
- 1. If _int32bit_ ≥ 231, return 𝔽(_int32bit_ - 232); otherwise return 𝔽(_int32bit_).
+ 1. Let _int_ be ? ToIntegerOrInfinity(_arg_).
+ 1. Return 𝔽(ToFixedSizeInteger(_int_, ~signed~, 32)).
-
- Given the above definition of ToInt32:
-
- -
- The ToInt32 abstract operation is idempotent: if applied to a result that it produced, the second application leaves that value unchanged.
-
- -
- ToInt32(ToUint32(_x_)) is the same value as ToInt32(_x_) for all values of _x_. (It is to preserve this latter property that *+∞*𝔽 and *-∞*𝔽 are mapped to *+0*𝔽.)
-
- -
- ToInt32 maps *-0*𝔽 to *+0*𝔽.
-
-
-
ToUint32 (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing an integral Number or a throw completion
- description
- - It converts _argument_ to one of 232 integral Number values in the inclusive interval from *+0*𝔽 to 𝔽(232 - 1).
+ - It converts _arg_ to one of 232 integral Number values in the inclusive interval from *+0*𝔽 to 𝔽(232 - 1).
- 1. Let _number_ be ? ToNumber(_argument_).
- 1. If _number_ is not finite or _number_ is either *+0*𝔽 or *-0*𝔽, return *+0*𝔽.
- 1. Let _int_ be truncate(ℝ(_number_)).
- 1. Let _int32bit_ be _int_ modulo 232.
- 1. [id="step-touint32-return"] Return 𝔽(_int32bit_).
+ 1. Let _int_ be ? ToIntegerOrInfinity(_arg_).
+ 1. Return 𝔽(ToFixedSizeInteger(_int_, ~unsigned~, 32)).
-
- Given the above definition of ToUint32:
-
- -
- Step
- -
- The ToUint32 abstract operation is idempotent: if applied to a result that it produced, the second application leaves that value unchanged.
-
- -
- ToUint32(ToInt32(_x_)) is the same value as ToUint32(_x_) for all values of _x_. (It is to preserve this latter property that *+∞*𝔽 and *-∞*𝔽 are mapped to *+0*𝔽.)
-
- -
- ToUint32 maps *-0*𝔽 to *+0*𝔽.
-
-
-
ToInt16 (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing an integral Number or a throw completion
- description
- - It converts _argument_ to one of 216 integral Number values in the inclusive interval from 𝔽(-215) to 𝔽(215 - 1).
+ - It converts _arg_ to one of 216 integral Number values in the inclusive interval from 𝔽(-215) to 𝔽(215 - 1), excluding *-0*𝔽.
- 1. Let _number_ be ? ToNumber(_argument_).
- 1. If _number_ is not finite or _number_ is either *+0*𝔽 or *-0*𝔽, return *+0*𝔽.
- 1. Let _int_ be truncate(ℝ(_number_)).
- 1. Let _int16bit_ be _int_ modulo 216.
- 1. If _int16bit_ ≥ 215, return 𝔽(_int16bit_ - 216); otherwise return 𝔽(_int16bit_).
+ 1. Let _int_ be ? ToIntegerOrInfinity(_arg_).
+ 1. Return 𝔽(ToFixedSizeInteger(_int_, ~signed~, 16)).
ToUint16 (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing an integral Number or a throw completion
- description
- - It converts _argument_ to one of 216 integral Number values in the inclusive interval from *+0*𝔽 to 𝔽(216 - 1).
+ - It converts _arg_ to one of 216 integral Number values in the inclusive interval from *+0*𝔽 to 𝔽(216 - 1).
- 1. Let _number_ be ? ToNumber(_argument_).
- 1. If _number_ is not finite or _number_ is either *+0*𝔽 or *-0*𝔽, return *+0*𝔽.
- 1. Let _int_ be truncate(ℝ(_number_)).
- 1. [id="step-touint16-mod"] Let _int16bit_ be _int_ modulo 216.
- 1. Return 𝔽(_int16bit_).
+ 1. Let _int_ be ? ToIntegerOrInfinity(_arg_).
+ 1. Return 𝔽(ToFixedSizeInteger(_int_, ~unsigned~, 16)).
-
- Given the above definition of ToUint16:
-
- -
- The substitution of 216 for 232 in step
- -
- ToUint16 maps *-0*𝔽 to *+0*𝔽.
-
-
-
ToInt8 (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing an integral Number or a throw completion
- description
- - It converts _argument_ to one of 28 integral Number values in the inclusive interval from *-128*𝔽 to *127*𝔽.
+ - It converts _arg_ to one of 28 integral Number values in the inclusive interval from *-128*𝔽 to *127*𝔽, excluding *-0*𝔽.
- 1. Let _number_ be ? ToNumber(_argument_).
- 1. If _number_ is not finite or _number_ is either *+0*𝔽 or *-0*𝔽, return *+0*𝔽.
- 1. Let _int_ be truncate(ℝ(_number_)).
- 1. Let _int8bit_ be _int_ modulo 28.
- 1. If _int8bit_ ≥ 27, return 𝔽(_int8bit_ - 28); otherwise return 𝔽(_int8bit_).
+ 1. Let _int_ be ? ToIntegerOrInfinity(_arg_).
+ 1. Return 𝔽(ToFixedSizeInteger(_int_, ~signed~, 8)).
ToUint8 (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing an integral Number or a throw completion
- description
- - It converts _argument_ to one of 28 integral Number values in the inclusive interval from *+0*𝔽 to *255*𝔽.
+ - It converts _arg_ to one of 28 integral Number values in the inclusive interval from *+0*𝔽 to *255*𝔽.
- 1. Let _number_ be ? ToNumber(_argument_).
- 1. If _number_ is not finite or _number_ is either *+0*𝔽 or *-0*𝔽, return *+0*𝔽.
- 1. Let _int_ be truncate(ℝ(_number_)).
- 1. Let _int8bit_ be _int_ modulo 28.
- 1. Return 𝔽(_int8bit_).
+ 1. Let _int_ be ? ToIntegerOrInfinity(_arg_).
+ 1. Return 𝔽(ToFixedSizeInteger(_int_, ~unsigned~, 8)).
ToUint8Clamp (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing an integral Number or a throw completion
- description
- - It clamps and rounds _argument_ to one of 28 integral Number values in the inclusive interval from *+0*𝔽 to *255*𝔽.
+ - It clamps and rounds _arg_ to one of 28 integral Number values in the inclusive interval from *+0*𝔽 to *255*𝔽.
- 1. Let _number_ be ? ToNumber(_argument_).
+ 1. Let _number_ be ? ToNumber(_arg_).
1. If _number_ is *NaN*, return *+0*𝔽.
1. Let _mv_ be the extended mathematical value of _number_.
1. Let _clamped_ be the result of clamping _mv_ between 0 and 255.
1. Let _f_ be floor(_clamped_).
1. If _clamped_ < _f_ + 0.5, return 𝔽(_f_).
1. If _clamped_ > _f_ + 0.5, return 𝔽(_f_ + 1).
- 1. If _f_ is even, return 𝔽(_f_). Otherwise, return 𝔽(_f_ + 1).
+ 1. If _f_ is even, return 𝔽(_f_).
+ 1. Return 𝔽(_f_ + 1).
Unlike most other ECMAScript integer conversion operations, ToUint8Clamp rounds rather than truncates non-integral values. It also uses “round half to even” tie-breaking, which differs from the “round half up” tie-breaking of `Math.round` .
@@ -5269,27 +5484,29 @@
ToBigInt (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing a BigInt or a throw completion
- description
- - It converts _argument_ to a BigInt value, or throws if an implicit conversion from Number would be required.
+ - It converts _arg_ to a BigInt value, or throws if an implicit conversion from Number would be required.
- 1. Let _prim_ be ? ToPrimitive(_argument_, ~number~).
- 1. Return the value that _prim_ corresponds to in
-
-
- Argument Type
-
-
- Result
-
-
+
+
+
+ Argument Type
+
+
+ Result
+
+
+
Undefined
@@ -5311,7 +5528,7 @@
Boolean
- Return `1n` if _prim_ is *true* and `0n` if _prim_ is *false*.
+ Return `1n` if _primitive_ is *true* and `0n` if _primitive_ is *false*.
@@ -5319,7 +5536,7 @@
BigInt
- Return _prim_.
+ Return _primitive_.
@@ -5336,7 +5553,7 @@
- 1. Let _n_ be StringToBigInt(_prim_).
+ 1. Let _n_ be StringToBigInt(_primitive_).
1. If _n_ is *undefined*, throw a *SyntaxError* exception.
1. Return _n_.
@@ -5357,13 +5574,13 @@
StringToBigInt (
- _str_: a String,
+ _string_: a String,
): a BigInt or *undefined*
- 1. Let _literal_ be ParseText(_str_, |StringIntegerLiteral|).
+ 1. Let _literal_ be ParseText(_string_, |StringIntegerLiteral|).
1. If _literal_ is a List of errors, return *undefined*.
1. Let _mv_ be the MV of _literal_.
1. Assert: _mv_ is an integer.
@@ -5401,163 +5618,95 @@ Runtime Semantics: MV
ToBigInt64 (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing a BigInt or a throw completion
- description
- - It converts _argument_ to one of 264 BigInt values in the inclusive interval from ℤ(-263) to ℤ(263 - 1).
+ - It converts _arg_ to one of 264 BigInt values in the inclusive interval from ℤ(-263) to ℤ(263 - 1).
- 1. Let _n_ be ? ToBigInt(_argument_).
- 1. Let _int64bit_ be ℝ(_n_) modulo 264.
- 1. If _int64bit_ ≥ 263, return ℤ(_int64bit_ - 264); otherwise return ℤ(_int64bit_).
+ 1. Let _int_ be ℝ(? ToBigInt(_arg_)).
+ 1. Return ℤ(ToFixedSizeInteger(_int_, ~signed~, 64)).
ToBigUint64 (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing a BigInt or a throw completion
- description
- - It converts _argument_ to one of 264 BigInt values in the inclusive interval from *0*ℤ to ℤ(264 - 1).
+ - It converts _arg_ to one of 264 BigInt values in the inclusive interval from *0*ℤ to ℤ(264 - 1).
- 1. Let _n_ be ? ToBigInt(_argument_).
- 1. Let _int64bit_ be ℝ(_n_) modulo 264.
- 1. Return ℤ(_int64bit_).
+ 1. Let _int_ be ℝ(? ToBigInt(_arg_)).
+ 1. Return ℤ(ToFixedSizeInteger(_int_, ~unsigned~, 64)).
ToString (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing a String or a throw completion
- description
- - It converts _argument_ to a value of type String.
+ - It converts _arg_ to a value of type String.
- 1. If _argument_ is a String, return _argument_.
- 1. If _argument_ is a Symbol, throw a *TypeError* exception.
- 1. If _argument_ is *undefined*, return *"undefined"*.
- 1. If _argument_ is *null*, return *"null"*.
- 1. If _argument_ is *true*, return *"true"*.
- 1. If _argument_ is *false*, return *"false"*.
- 1. If _argument_ is a Number, return Number::toString(_argument_, 10).
- 1. If _argument_ is a BigInt, return BigInt::toString(_argument_, 10).
- 1. Assert: _argument_ is an Object.
- 1. Let _primValue_ be ? ToPrimitive(_argument_, ~string~).
- 1. Assert: _primValue_ is not an Object.
- 1. Return ? ToString(_primValue_).
+ 1. If _arg_ is a String, return _arg_.
+ 1. If _arg_ is a Symbol, throw a *TypeError* exception.
+ 1. If _arg_ is *undefined*, return *"undefined"*.
+ 1. If _arg_ is *null*, return *"null"*.
+ 1. If _arg_ is *true*, return *"true"*.
+ 1. If _arg_ is *false*, return *"false"*.
+ 1. If _arg_ is a Number, return Number::toString(_arg_, 10).
+ 1. If _arg_ is a BigInt, return BigInt::toString(_arg_, 10).
+ 1. Assert: _arg_ is an Object.
+ 1. Let _primitiveValue_ be ? ToPrimitive(_arg_, ~string~).
+ 1. Assert: _primitiveValue_ is not an Object.
+ 1. Return ? ToString(_primitiveValue_).
-
+
ToObject (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing an Object or a throw completion
- description
- - It converts _argument_ to a value of type Object according to
+ - It converts _arg_ to a value of type Object.
-
-
-
-
- Argument Type
-
-
- Result
-
-
-
-
- Undefined
-
-
- Throw a *TypeError* exception.
-
-
-
-
- Null
-
-
- Throw a *TypeError* exception.
-
-
-
-
- Boolean
-
-
- Return a new Boolean object whose [[BooleanData]] internal slot is set to _argument_. See
-
-
-
- Number
-
-
- Return a new Number object whose [[NumberData]] internal slot is set to _argument_. See
-
-
-
- String
-
-
- Return a new String object whose [[StringData]] internal slot is set to _argument_. See
-
-
-
- Symbol
-
-
- Return a new Symbol object whose [[SymbolData]] internal slot is set to _argument_. See
-
-
-
- BigInt
-
-
- Return a new BigInt object whose [[BigIntData]] internal slot is set to _argument_. See
-
-
-
- Object
-
-
- Return _argument_.
-
-
-
-
+
+ 1. If _arg_ is either *undefined* or *null*, throw a *TypeError* exception.
+ 1. If _arg_ is a Boolean, return a new Boolean object whose [[BooleanData]] internal slot is set to _arg_. See
ToPropertyKey (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing a property key or a throw completion
- description
- - It converts _argument_ to a value that can be used as a property key.
+ - It converts _arg_ to a value that can be used as a property key.
- 1. Let _key_ be ? ToPrimitive(_argument_, ~string~).
+ 1. Let _key_ be ? ToPrimitive(_arg_, ~string~).
1. If _key_ is a Symbol, then
1. Return _key_.
1. Return ! ToString(_key_).
@@ -5567,53 +5716,53 @@
ToLength (
- _argument_: an ECMAScript language value,
- ): either a normal completion containing an integral Number or a throw completion
+ _arg_: an ECMAScript language value,
+ ): either a normal completion containing a non-negative integral Number or a throw completion
- description
- - It clamps and truncates _argument_ to an integral Number suitable for use as the length of an array-like object.
+ - It clamps and truncates _arg_ to a non-negative integral Number suitable for use as the length of an array-like object.
- 1. Let _len_ be ? ToIntegerOrInfinity(_argument_).
- 1. If _len_ ≤ 0, return *+0*𝔽.
- 1. Return 𝔽(min(_len_, 253 - 1)).
+ 1. Let _length_ be ? ToIntegerOrInfinity(_arg_).
+ 1. If _length_ ≤ 0, return *+0*𝔽.
+ 1. Return 𝔽(min(_length_, 253 - 1)).
CanonicalNumericIndexString (
- _argument_: a String,
+ _arg_: a String,
): a Number or *undefined*
- description
- - If _argument_ is either *"-0"* or exactly matches the result of ToString(_n_) for some Number value _n_, it returns the respective Number value. Otherwise, it returns *undefined*.
+ - If _arg_ is either *"-0"* or exactly matches ToString(_n_) for some Number value _n_, it returns the respective Number value. Otherwise, it returns *undefined*.
- 1. If _argument_ is *"-0"*, return *-0*𝔽.
- 1. Let _n_ be ! ToNumber(_argument_).
- 1. If ! ToString(_n_) is _argument_, return _n_.
+ 1. If _arg_ is *"-0"*, return *-0*𝔽.
+ 1. Let _n_ be ! ToNumber(_arg_).
+ 1. If ! ToString(_n_) is _arg_, return _n_.
1. Return *undefined*.
- A canonical numeric string is any String value for which the CanonicalNumericIndexString abstract operation does not return *undefined*.
+ A canonical numeric string is any String for which the CanonicalNumericIndexString abstract operation does not return *undefined*.
ToIndex (
- _value_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing a non-negative integer or a throw completion
- description
- - It converts _value_ to an integer and returns that integer if it is non-negative and corresponds with an integer index. Otherwise, it throws an exception.
+ - It converts _arg_ to an integer and returns that integer if it is non-negative and corresponds with an integer index. Otherwise, it throws an exception.
- 1. Let _integer_ be ? ToIntegerOrInfinity(_value_).
- 1. If _integer_ is not in the inclusive interval from 0 to 253 - 1, throw a *RangeError* exception.
- 1. Return _integer_.
+ 1. Let _int_ be ? ToIntegerOrInfinity(_arg_).
+ 1. If _int_ is not in the inclusive interval from 0 to 253 - 1, throw a *RangeError* exception.
+ 1. Return _int_.
@@ -5621,108 +5770,36 @@
Testing and Comparison Operations
-
+
RequireObjectCoercible (
- _argument_: an ECMAScript language value,
- ): either a normal completion containing an ECMAScript language value or a throw completion
+ _arg_: an ECMAScript language value,
+ ): either a normal completion containing ~unused~ or a throw completion
- description
- - It throws an error if _argument_ is a value that cannot be converted to an Object using ToObject. It is defined by
+ - It throws an error if _arg_ is a value that cannot be converted to an Object using ToObject.
-
-
-
-
- Argument Type
-
-
- Result
-
-
-
-
- Undefined
-
-
- Throw a *TypeError* exception.
-
-
-
-
- Null
-
-
- Throw a *TypeError* exception.
-
-
-
-
- Boolean
-
-
- Return _argument_.
-
-
-
-
- Number
-
-
- Return _argument_.
-
-
-
-
- String
-
-
- Return _argument_.
-
-
-
-
- Symbol
-
-
- Return _argument_.
-
-
-
-
- BigInt
-
-
- Return _argument_.
-
-
-
-
- Object
-
-
- Return _argument_.
-
-
-
-
+
+ 1. If _arg_ is either *undefined* or *null*, throw a *TypeError* exception.
+ 1. Return ~unused~.
+
IsArray (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing a Boolean or a throw completion
- 1. If _argument_ is not an Object, return *false*.
- 1. If _argument_ is an Array exotic object, return *true*.
- 1. If _argument_ is a Proxy exotic object, then
- 1. Perform ? ValidateNonRevokedProxy(_argument_).
- 1. Let _proxyTarget_ be _argument_.[[ProxyTarget]].
+ 1. If _arg_ is not an Object, return *false*.
+ 1. If _arg_ is an Array exotic object, return *true*.
+ 1. If _arg_ is a Proxy exotic object, then
+ 1. Perform ? ValidateNonRevokedProxy(_arg_).
+ 1. Let _proxyTarget_ be _arg_.[[ProxyTarget]].
1. Return ? IsArray(_proxyTarget_).
1. Return *false*.
@@ -5731,16 +5808,16 @@
IsCallable (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): a Boolean
- description
- - It determines if _argument_ is a callable function with a [[Call]] internal method.
+ - It determines if _arg_ is a callable function with a [[Call]] internal method.
- 1. If _argument_ is not an Object, return *false*.
- 1. If _argument_ has a [[Call]] internal method, return *true*.
+ 1. If _arg_ is not an Object, return *false*.
+ 1. If _arg_ has a [[Call]] internal method, return *true*.
1. Return *false*.
@@ -5748,16 +5825,16 @@
IsConstructor (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): a Boolean
- description
- - It determines if _argument_ is a function object with a [[Construct]] internal method.
+ - It determines if _arg_ is a function object with a [[Construct]] internal method.
- 1. If _argument_ is not an Object, return *false*.
- 1. If _argument_ has a [[Construct]] internal method, return *true*.
+ 1. If _arg_ is not an Object, return *false*.
+ 1. If _arg_ has a [[Construct]] internal method, return *true*.
1. Return *false*.
@@ -5765,49 +5842,31 @@
IsExtensible (
- _O_: an Object,
+ _obj_: an Object,
): either a normal completion containing a Boolean or a throw completion
- description
- - It is used to determine whether additional properties can be added to _O_.
+ - It is used to determine whether additional properties can be added to _obj_.
- 1. Return ? _O_.[[IsExtensible]] ().
-
-
-
-
-
- IsIntegralNumber (
- _argument_: an ECMAScript language value,
- ): a Boolean
-
-
- - description
- - It determines if _argument_ is a finite integral Number value.
-
-
- 1. If _argument_ is not a Number, return *false*.
- 1. If _argument_ is not finite, return *false*.
- 1. If truncate(ℝ(_argument_)) ≠ ℝ(_argument_), return *false*.
- 1. Return *true*.
+ 1. Return ? _obj_.[[IsExtensible]]() .
IsRegExp (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing a Boolean or a throw completion
- 1. If _argument_ is not an Object, return *false*.
- 1. Let _matcher_ be ? Get(_argument_, @@match).
+ 1. If _arg_ is not an Object, return *false*.
+ 1. Let _matcher_ be ? Get(_arg_, %Symbol.match%).
1. If _matcher_ is not *undefined*, return ToBoolean(_matcher_).
- 1. If _argument_ has a [[RegExpMatcher]] internal slot, return *true*.
+ 1. If _arg_ has a [[RegExpMatcher]] internal slot, return *true*.
1. Return *false*.
@@ -5823,16 +5882,40 @@
- It interprets _string_ as a sequence of UTF-16 encoded code points, as described in
- 1. Let _len_ be the length of _string_.
+ 1. Let _length_ be the length of _string_.
1. Let _k_ be 0.
- 1. Repeat, while _k_ < _len_,
- 1. Let _cp_ be CodePointAt(_string_, _k_).
- 1. If _cp_.[[IsUnpairedSurrogate]] is *true*, return *false*.
- 1. Set _k_ to _k_ + _cp_.[[CodeUnitCount]].
+ 1. Repeat, while _k_ < _length_,
+ 1. Let _codePoint_ be CodePointAt(_string_, _k_).
+ 1. If _codePoint_.[[IsUnpairedSurrogate]] is *true*, return *false*.
+ 1. Set _k_ to _k_ + _codePoint_.[[CodeUnitCount]].
1. Return *true*.
+
+
+ SameType (
+ _x_: an ECMAScript language value,
+ _y_: an ECMAScript language value,
+ ): a Boolean
+
+
+ - description
+ - It determines whether or not the two arguments are the same type.
+
+
+ 1. If _x_ is *undefined* and _y_ is *undefined*, return *true*.
+ 1. If _x_ is *null* and _y_ is *null*, return *true*.
+ 1. If _x_ is a Boolean and _y_ is a Boolean, return *true*.
+ 1. If _x_ is a Number and _y_ is a Number, return *true*.
+ 1. If _x_ is a BigInt and _y_ is a BigInt, return *true*.
+ 1. If _x_ is a Symbol and _y_ is a Symbol, return *true*.
+ 1. If _x_ is a String and _y_ is a String, return *true*.
+ 1. If _x_ is an Object and _y_ is an Object, return *true*.
+ 1. Return *false*.
+
+
+
SameValue (
@@ -5845,7 +5928,7 @@
- It determines whether or not the two arguments are the same value.
- 1. If Type(_x_) is not Type(_y_), return *false*.
+ 1. If SameType(_x_, _y_) is *false*, return *false*.
1. If _x_ is a Number, then
1. Return Number::sameValue(_x_, _y_).
1. Return SameValueNonNumber(_x_, _y_).
@@ -5867,7 +5950,7 @@
- It determines whether or not the two arguments are the same value (ignoring the difference between *+0*𝔽 and *-0*𝔽).
- 1. If Type(_x_) is not Type(_y_), return *false*.
+ 1. If SameType(_x_, _y_) is *false*, return *false*.
1. If _x_ is a Number, then
1. Return Number::sameValueZero(_x_, _y_).
1. Return SameValueNonNumber(_x_, _y_).
@@ -5887,22 +5970,26 @@
- 1. Assert: Type(_x_) is Type(_y_).
- 1. If _x_ is either *null* or *undefined*, return *true*.
+ 1. Assert: SameType(_x_, _y_) is *true*.
+ 1. If _x_ is either *undefined* or *null*, return *true*.
1. If _x_ is a BigInt, then
1. Return BigInt::equal(_x_, _y_).
1. If _x_ is a String, then
- 1. If _x_ and _y_ have the same length and the same code units in the same positions, return *true*; otherwise, return *false*.
+ 1. If _x_ and _y_ have the same length and the same code units in the same positions, return *true*.
+ 1. Return *false*.
1. If _x_ is a Boolean, then
- 1. If _x_ and _y_ are both *true* or both *false*, return *true*; otherwise, return *false*.
+ 1. If _x_ is *true* and _y_ is *true*, return *true*.
+ 1. If _x_ is *false* and _y_ is *false*, return *true*.
+ 1. Return *false*.
1. NOTE: All other ECMAScript language values are compared by identity.
- 1. If _x_ is _y_, return *true*; otherwise, return *false*.
+ 1. If _x_ is _y_, return *true*.
+ 1. Return *false*.
For expository purposes, some cases are handled separately within this algorithm even if it is unnecessary to do so.
- The specifics of what "_x_ is _y_" means are detailed in
@@ -5911,15 +5998,15 @@
IsLessThan (
_x_: an ECMAScript language value,
_y_: an ECMAScript language value,
- _LeftFirst_: a Boolean,
+ _leftFirst_: a Boolean,
): either a normal completion containing either a Boolean or *undefined*, or a throw completion
- description
- - It provides the semantics for the comparison _x_ < _y_, returning *true*, *false*, or *undefined* (which indicates that at least one operand is *NaN*). The _LeftFirst_ flag is used to control the order in which operations with potentially visible side-effects are performed upon _x_ and _y_. It is necessary because ECMAScript specifies left to right evaluation of expressions. If _LeftFirst_ is *true*, the _x_ parameter corresponds to an expression that occurs to the left of the _y_ parameter's corresponding expression. If _LeftFirst_ is *false*, the reverse is the case and operations must be performed upon _y_ before _x_.
+ - It provides the semantics for the comparison _x_ < _y_, returning *true*, *false*, or *undefined* (which indicates that the operands could not be coerced to comparable values of the same numeric type). The _leftFirst_ flag is used to control the order in which operations with potentially visible side-effects are performed upon _x_ and _y_. It is necessary because ECMAScript specifies left to right evaluation of expressions. If _leftFirst_ is *true*, the _x_ parameter corresponds to an expression that occurs to the left of the _y_ parameter's corresponding expression. If _leftFirst_ is *false*, the reverse is the case and operations must be performed upon _y_ before _x_.
- 1. If _LeftFirst_ is *true*, then
+ 1. If _leftFirst_ is *true*, then
1. Let _px_ be ? ToPrimitive(_x_, ~number~).
1. Let _py_ be ? ToPrimitive(_y_, ~number~).
1. Else,
@@ -5934,30 +6021,29 @@
1. Let _cy_ be the numeric value of the code unit at index _i_ within _py_.
1. If _cx_ < _cy_, return *true*.
1. If _cx_ > _cy_, return *false*.
- 1. If _lx_ < _ly_, return *true*. Otherwise, return *false*.
- 1. Else,
- 1. If _px_ is a BigInt and _py_ is a String, then
- 1. Let _ny_ be StringToBigInt(_py_).
- 1. If _ny_ is *undefined*, return *undefined*.
- 1. Return BigInt::lessThan(_px_, _ny_).
- 1. If _px_ is a String and _py_ is a BigInt, then
- 1. Let _nx_ be StringToBigInt(_px_).
- 1. If _nx_ is *undefined*, return *undefined*.
- 1. Return BigInt::lessThan(_nx_, _py_).
- 1. NOTE: Because _px_ and _py_ are primitive values, evaluation order is not important.
- 1. Let _nx_ be ? ToNumeric(_px_) .
- 1. Let _ny_ be ? ToNumeric(_py_) .
- 1. If Type(_nx_) is Type(_ny_), then
- 1. If _nx_ is a Number, then
- 1. Return Number::lessThan(_nx_, _ny_).
- 1. Else,
- 1. Assert: _nx_ is a BigInt.
- 1. Return BigInt::lessThan(_nx_, _ny_).
- 1. Assert: _nx_ is a BigInt and _ny_ is a Number, or _nx_ is a Number and _ny_ is a BigInt.
- 1. If _nx_ or _ny_ is *NaN*, return *undefined*.
- 1. If _nx_ is *-∞*𝔽 or _ny_ is *+∞*𝔽, return *true*.
- 1. If _nx_ is *+∞*𝔽 or _ny_ is *-∞*𝔽, return *false*.
- 1. If ℝ(_nx_) < ℝ(_ny_), return *true*; otherwise return *false*.
+ 1. If _lx_ < _ly_, return *true*.
+ 1. Return *false*.
+ 1. If _px_ is a BigInt and _py_ is a String, then
+ 1. Let _ny_ be StringToBigInt(_py_).
+ 1. If _ny_ is *undefined*, return *undefined*.
+ 1. Return BigInt::lessThan(_px_, _ny_).
+ 1. If _px_ is a String and _py_ is a BigInt, then
+ 1. Let _nx_ be StringToBigInt(_px_).
+ 1. If _nx_ is *undefined*, return *undefined*.
+ 1. Return BigInt::lessThan(_nx_, _py_).
+ 1. NOTE: Because _px_ and _py_ are primitive values, evaluation order is not important.
+ 1. Let _nx_ be ? ToNumeric(_px_) .
+ 1. Let _ny_ be ? ToNumeric(_py_) .
+ 1. If SameType(_nx_, _ny_) is *true*, then
+ 1. If _nx_ is a Number, return Number::lessThan(_nx_, _ny_).
+ 1. Assert: _nx_ is a BigInt.
+ 1. Return BigInt::lessThan(_nx_, _ny_).
+ 1. Assert: _nx_ is a BigInt and _ny_ is a Number, or _nx_ is a Number and _ny_ is a BigInt.
+ 1. If _nx_ is *NaN* or _ny_ is *NaN*, return *undefined*.
+ 1. If _nx_ is *-∞*𝔽 or _ny_ is *+∞*𝔽, return *true*.
+ 1. If _nx_ is *+∞*𝔽 or _ny_ is *-∞*𝔽, return *false*.
+ 1. If ℝ(_nx_) < ℝ(_ny_), return *true*.
+ 1. Return *false*.
Step
@@ -5967,7 +6053,7 @@
-
+
IsLooselyEqual (
_x_: an ECMAScript language value,
@@ -5979,11 +6065,13 @@
- It provides the semantics for the `==` operator.
- 1. If Type(_x_) is Type(_y_), then
+ 1. If SameType(_x_, _y_) is *true*, then
1. Return IsStrictlyEqual(_x_, _y_).
1. If _x_ is *null* and _y_ is *undefined*, return *true*.
1. If _x_ is *undefined* and _y_ is *null*, return *true*.
- 1. [id="step-abstract-equality-comparison-web-compat-insertion-point"] NOTE: This step is replaced in section
1. If _x_ is an Object and _y_ is either a String, a Number, a BigInt, or a Symbol, return ! IsLooselyEqual(? ToPrimitive(_x_), _y_).
1. If _x_ is a BigInt and _y_ is a Number, or if _x_ is a Number and _y_ is a BigInt, then
1. If _x_ is not finite or _y_ is not finite, return *false*.
- 1. If ℝ(_x_) = ℝ(_y_), return *true*; otherwise return *false*.
+ 1. If ℝ(_x_) = ℝ(_y_), return *true*.
+ 1. Return *false*.
1. Return *false*.
@@ -6014,7 +6103,7 @@
- It provides the semantics for the `===` operator.
- 1. If Type(_x_) is not Type(_y_), return *false*.
+ 1. If SameType(_x_, _y_) is *false*, return *false*.
1. If _x_ is a Number, then
1. Return Number::equal(_x_, _y_).
1. Return SameValueNonNumber(_x_, _y_).
@@ -6040,7 +6129,10 @@
+ 1. Set _internalSlotsList_ to the list-concatenation of _internalSlotsList_ and « [[PrivateElements]] ».
1. Let _obj_ be a newly created object with an internal slot for each name in _internalSlotsList_.
+ 1. NOTE: As described in
Get (
- _O_: an Object,
- _P_: a property key,
+ _obj_: an Object,
+ _propertyKey_: a property key,
): either a normal completion containing an ECMAScript language value or a throw completion
@@ -6065,15 +6157,15 @@
- It is used to retrieve the value of a specific property of an object.
- 1. Return ? _O_.[[Get]] (_P_, _O_).
+ 1. Return ? _obj_.[[Get]](_propertyKey_, _obj_) .
GetV (
- _V_: an ECMAScript language value,
- _P_: a property key,
+ _value_: an ECMAScript language value,
+ _propertyKey_: a property key,
): either a normal completion containing an ECMAScript language value or a throw completion
@@ -6081,27 +6173,27 @@
- It is used to retrieve the value of a specific property of an ECMAScript language value. If the value is not an object, the property lookup is performed using a wrapper object appropriate for the type of the value.
- 1. Let _O_ be ? ToObject(_V_).
- 1. Return ? _O_.[[Get]] (_P_, _V_).
+ 1. Let _obj_ be ? ToObject(_value_).
+ 1. Return ? _obj_.[[Get]](_propertyKey_, _value_) .
Set (
- _O_: an Object,
- _P_: a property key,
- _V_: an ECMAScript language value,
- _Throw_: a Boolean,
+ _obj_: an Object,
+ _propertyKey_: a property key,
+ _value_: an ECMAScript language value,
+ _throw_: a Boolean,
): either a normal completion containing ~unused~ or a throw completion
- description
- - It is used to set the value of a specific property of an object. _V_ is the new value for the property.
+ - It is used to set the value of a specific property of an object. _value_ is the new value for the property.
- 1. Let _success_ be ? _O_.[[Set]] (_P_, _V_, _O_).
- 1. If _success_ is *false* and _Throw_ is *true*, throw a *TypeError* exception.
+ 1. Let _success_ be ? _obj_.[[Set]](_propertyKey_, _value_, _obj_) .
+ 1. If _success_ is *false* and _throw_ is *true*, throw a *TypeError* exception.
1. Return ~unused~.
@@ -6109,9 +6201,9 @@
CreateDataProperty (
- _O_: an Object,
- _P_: a property key,
- _V_: an ECMAScript language value,
+ _obj_: an Object,
+ _propertyKey_: a property key,
+ _value_: an ECMAScript language value,
): either a normal completion containing a Boolean or a throw completion
@@ -6119,20 +6211,20 @@
- It is used to create a new own property of an object.
- 1. Let _newDesc_ be the PropertyDescriptor { [[Value]]: _V_, [[Writable]]: *true*, [[Enumerable]]: *true*, [[Configurable]]: *true* }.
- 1. Return ? _O_.[[DefineOwnProperty]] (_P_, _newDesc_).
+ 1. Let _newDesc_ be the PropertyDescriptor { [[Value]]: _value_, [[Writable]]: *true*, [[Enumerable]]: *true*, [[Configurable]]: *true* }.
+ 1. Return ? _obj_.[[DefineOwnProperty]](_propertyKey_, _newDesc_) .
- This abstract operation creates a property whose attributes are set to the same defaults used for properties created by the ECMAScript language assignment operator. Normally, the property will not already exist. If it does exist and is not configurable or if _O_ is not extensible, [[DefineOwnProperty]] will return *false*.
+ This abstract operation creates a property whose attributes are set to the same defaults used for properties created by the ECMAScript language assignment operator. Normally, the property will not already exist. If it does exist and is not configurable or if _obj_ is not extensible, [[DefineOwnProperty]] will return *false*.
CreateDataPropertyOrThrow (
- _O_: an Object,
- _P_: a property key,
- _V_: an ECMAScript language value,
+ _obj_: an Object,
+ _propertyKey_: a property key,
+ _value_: an ECMAScript language value,
): either a normal completion containing ~unused~ or a throw completion
@@ -6140,21 +6232,21 @@
- It is used to create a new own property of an object. It throws a *TypeError* exception if the requested property update cannot be performed.
- 1. Let _success_ be ? CreateDataProperty(_O_, _P_, _V_).
+ 1. Let _success_ be ? CreateDataProperty(_obj_, _propertyKey_, _value_).
1. If _success_ is *false*, throw a *TypeError* exception.
1. Return ~unused~.
- This abstract operation creates a property whose attributes are set to the same defaults used for properties created by the ECMAScript language assignment operator. Normally, the property will not already exist. If it does exist and is not configurable or if _O_ is not extensible, [[DefineOwnProperty]] will return *false* causing this operation to throw a *TypeError* exception.
+ This abstract operation creates a property whose attributes are set to the same defaults used for properties created by the ECMAScript language assignment operator. Normally, the property will not already exist. If it does exist and is not configurable or if _obj_ is not extensible, [[DefineOwnProperty]] will return *false* causing this operation to throw a *TypeError* exception.
CreateNonEnumerableDataPropertyOrThrow (
- _O_: an Object,
- _P_: a property key,
- _V_: an ECMAScript language value,
+ _obj_: an Object,
+ _propertyKey_: a property key,
+ _value_: an ECMAScript language value,
): ~unused~
@@ -6162,9 +6254,9 @@
- It is used to create a new non-enumerable own property of an ordinary object.
- 1. Assert: _O_ is an ordinary, extensible object with no non-configurable properties.
- 1. Let _newDesc_ be the PropertyDescriptor { [[Value]]: _V_, [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *true* }.
- 1. Perform ! DefinePropertyOrThrow(_O_, _P_, _newDesc_).
+ 1. Assert: _obj_ is an ordinary, extensible object with no non-configurable properties.
+ 1. Let _newDesc_ be the PropertyDescriptor { [[Value]]: _value_, [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *true* }.
+ 1. Perform ! DefinePropertyOrThrow(_obj_, _propertyKey_, _newDesc_).
1. Return ~unused~.
@@ -6175,9 +6267,9 @@
DefinePropertyOrThrow (
- _O_: an Object,
- _P_: a property key,
- _desc_: a Property Descriptor,
+ _obj_: an Object,
+ _propertyKey_: a property key,
+ _propertyDesc_: a Property Descriptor,
): either a normal completion containing ~unused~ or a throw completion
@@ -6185,7 +6277,7 @@
- It is used to call the [[DefineOwnProperty]] internal method of an object in a manner that will throw a *TypeError* exception if the requested property update cannot be performed.
- 1. Let _success_ be ? _O_.[[DefineOwnProperty]] (_P_, _desc_).
+ 1. Let _success_ be ? _obj_.[[DefineOwnProperty]](_propertyKey_, _propertyDesc_) .
1. If _success_ is *false*, throw a *TypeError* exception.
1. Return ~unused~.
@@ -6194,8 +6286,8 @@
DeletePropertyOrThrow (
- _O_: an Object,
- _P_: a property key,
+ _obj_: an Object,
+ _propertyKey_: a property key,
): either a normal completion containing ~unused~ or a throw completion
@@ -6203,7 +6295,7 @@
- It is used to remove a specific own property of an object. It throws an exception if the property is not configurable.
- 1. Let _success_ be ? _O_.[[Delete]] (_P_).
+ 1. Let _success_ be ? _obj_.[[Delete]](_propertyKey_) .
1. If _success_ is *false*, throw a *TypeError* exception.
1. Return ~unused~.
@@ -6212,8 +6304,8 @@
GetMethod (
- _V_: an ECMAScript language value,
- _P_: a property key,
+ _value_: an ECMAScript language value,
+ _propertyKey_: a property key,
): either a normal completion containing either a function object or *undefined*, or a throw completion
@@ -6221,7 +6313,7 @@
- It is used to get the value of a specific property of an ECMAScript language value when the value of the property is expected to be a function.
- 1. Let _func_ be ? GetV(_V_, _P_).
+ 1. Let _func_ be ? GetV(_value_, _propertyKey_).
1. If _func_ is either *undefined* or *null*, return *undefined*.
1. If IsCallable(_func_) is *false*, throw a *TypeError* exception.
1. Return _func_.
@@ -6231,8 +6323,8 @@
HasProperty (
- _O_: an Object,
- _P_: a property key,
+ _obj_: an Object,
+ _propertyKey_: a property key,
): either a normal completion containing a Boolean or a throw completion
@@ -6240,15 +6332,15 @@
- It is used to determine whether an object has a property with the specified property key. The property may be either own or inherited.
- 1. Return ? _O_.[[HasProperty]] (_P_).
+ 1. Return ? _obj_.[[HasProperty]](_propertyKey_) .
HasOwnProperty (
- _O_: an Object,
- _P_: a property key,
+ _obj_: an Object,
+ _propertyKey_: a property key,
): either a normal completion containing a Boolean or a throw completion
@@ -6256,8 +6348,8 @@
- It is used to determine whether an object has an own property with the specified property key.
- 1. Let _desc_ be ? _O_.[[GetOwnProperty]] (_P_).
- 1. If _desc_ is *undefined*, return *false*.
+ 1. Let _propertyDesc_ be ? _obj_.[[GetOwnProperty]](_propertyKey_) .
+ 1. If _propertyDesc_ is *undefined*, return *false*.
1. Return *true*.
@@ -6265,38 +6357,38 @@
Call (
- _F_: an ECMAScript language value,
- _V_: an ECMAScript language value,
- optional _argumentsList_: a List of ECMAScript language values,
+ _func_: an ECMAScript language value,
+ _thisValue_: an ECMAScript language value,
+ optional _argList_: a List of ECMAScript language values,
): either a normal completion containing an ECMAScript language value or a throw completion
- description
- - It is used to call the [[Call]] internal method of a function object. _F_ is the function object, _V_ is an ECMAScript language value that is the *this* value of the [[Call]], and _argumentsList_ is the value passed to the corresponding argument of the internal method. If _argumentsList_ is not present, a new empty List is used as its value.
+ - It is used to call the [[Call]] internal method of a function object. _func_ is the function object, _thisValue_ is an ECMAScript language value that is the *this* value of the [[Call]], and _argList_ is the value passed to the corresponding argument of the internal method. If _argList_ is not present, a new empty List is used as its value.
- 1. If _argumentsList_ is not present, set _argumentsList_ to a new empty List.
- 1. If IsCallable(_F_) is *false*, throw a *TypeError* exception.
- 1. Return ? _F_.[[Call]] (_V_, _argumentsList_).
+ 1. If _argList_ is not present, set _argList_ to a new empty List.
+ 1. If IsCallable(_func_) is *false*, throw a *TypeError* exception.
+ 1. Return ? _func_.[[Call]](_thisValue_, _argList_) .
Construct (
- _F_: a constructor,
- optional _argumentsList_: a List of ECMAScript language values,
+ _ctor_: a constructor,
+ optional _argList_: a List of ECMAScript language values,
optional _newTarget_: a constructor,
): either a normal completion containing an Object or a throw completion
- description
- - It is used to call the [[Construct]] internal method of a function object. _argumentsList_ and _newTarget_ are the values to be passed as the corresponding arguments of the internal method. If _argumentsList_ is not present, a new empty List is used as its value. If _newTarget_ is not present, _F_ is used as its value.
+ - It is used to call the [[Construct]] internal method of a function object. _argList_ and _newTarget_ are the values to be passed as the corresponding arguments of the internal method. If _argList_ is not present, a new empty List is used as its value. If _newTarget_ is not present, _ctor_ is used as its value.
- 1. If _newTarget_ is not present, set _newTarget_ to _F_.
- 1. If _argumentsList_ is not present, set _argumentsList_ to a new empty List.
- 1. Return ? _F_.[[Construct]] (_argumentsList_, _newTarget_).
+ 1. If _newTarget_ is not present, set _newTarget_ to _ctor_.
+ 1. If _argList_ is not present, set _argList_ to a new empty List.
+ 1. Return ? _ctor_.[[Construct]](_argList_, _newTarget_) .
If _newTarget_ is not present, this operation is equivalent to: `new F(...argumentsList)`
@@ -6306,7 +6398,7 @@
SetIntegrityLevel (
- _O_: an Object,
+ _obj_: an Object,
_level_: ~sealed~ or ~frozen~,
): either a normal completion containing a Boolean or a throw completion
@@ -6315,22 +6407,22 @@
- It is used to fix the set of own properties of an object.
- 1. Let _status_ be ? _O_.[[PreventExtensions]]().
+ 1. Let _status_ be ? _obj_.[[PreventExtensions]]().
1. If _status_ is *false*, return *false*.
- 1. Let _keys_ be ? _O_.[[OwnPropertyKeys]]().
+ 1. Let _keys_ be ? _obj_.[[OwnPropertyKeys]]().
1. If _level_ is ~sealed~, then
- 1. For each element _k_ of _keys_, do
- 1. Perform ? DefinePropertyOrThrow(_O_, _k_, PropertyDescriptor { [[Configurable]]: *false* }).
+ 1. For each element _key_ of _keys_, do
+ 1. Perform ? DefinePropertyOrThrow(_obj_, _key_, PropertyDescriptor { [[Configurable]]: *false* }).
1. Else,
1. Assert: _level_ is ~frozen~.
- 1. For each element _k_ of _keys_, do
- 1. Let _currentDesc_ be ? _O_.[[GetOwnProperty]] (_k_).
+ 1. For each element _key_ of _keys_, do
+ 1. Let _currentDesc_ be ? _obj_.[[GetOwnProperty]](_key_) .
1. If _currentDesc_ is not *undefined*, then
1. If IsAccessorDescriptor(_currentDesc_) is *true*, then
- 1. Let _desc_ be the PropertyDescriptor { [[Configurable]]: *false* }.
+ 1. Let _propertyDesc_ be the PropertyDescriptor { [[Configurable]]: *false* }.
1. Else,
- 1. Let _desc_ be the PropertyDescriptor { [[Configurable]]: *false*, [[Writable]]: *false* }.
- 1. Perform ? DefinePropertyOrThrow(_O_, _k_, _desc_).
+ 1. Let _propertyDesc_ be the PropertyDescriptor { [[Configurable]]: *false*, [[Writable]]: *false* }.
+ 1. Perform ? DefinePropertyOrThrow(_obj_, _key_, _propertyDesc_).
1. Return *true*.
@@ -6338,7 +6430,7 @@
TestIntegrityLevel (
- _O_: an Object,
+ _obj_: an Object,
_level_: ~sealed~ or ~frozen~,
): either a normal completion containing a Boolean or a throw completion
@@ -6347,12 +6439,12 @@
- It is used to determine if the set of own properties of an object are fixed.
- 1. Let _extensible_ be ? IsExtensible(_O_).
+ 1. Let _extensible_ be ? IsExtensible(_obj_).
1. If _extensible_ is *true*, return *false*.
1. NOTE: If the object is extensible, none of its properties are examined.
- 1. Let _keys_ be ? _O_.[[OwnPropertyKeys]]().
- 1. For each element _k_ of _keys_, do
- 1. Let _currentDesc_ be ? _O_.[[GetOwnProperty]] (_k_).
+ 1. Let _keys_ be ? _obj_.[[OwnPropertyKeys]]().
+ 1. For each element _key_ of _keys_, do
+ 1. Let _currentDesc_ be ? _obj_.[[GetOwnProperty]](_key_) .
1. If _currentDesc_ is not *undefined*, then
1. If _currentDesc_.[[Configurable]] is *true*, return *false*.
1. If _level_ is ~frozen~ and IsDataDescriptor(_currentDesc_) is *true*, then
@@ -6374,8 +6466,8 @@
1. Let _array_ be ! ArrayCreate(0).
1. Let _n_ be 0.
- 1. For each element _e_ of _elements_, do
- 1. Perform ! CreateDataPropertyOrThrow(_array_, ! ToString(𝔽(_n_)), _e_).
+ 1. For each element _element_ of _elements_, do
+ 1. Perform ! CreateDataPropertyOrThrow(_array_, ! ToString(𝔽(_n_)), _element_).
1. Set _n_ to _n_ + 1.
1. Return _array_.
@@ -6407,23 +6499,23 @@
CreateListFromArrayLike (
_obj_: an ECMAScript language value,
- optional _elementTypes_: a List of names of ECMAScript Language Types,
+ optional _validElementTypes_: ~all~ or ~property-key~,
): either a normal completion containing a List of ECMAScript language values or a throw completion
- description
- - It is used to create a List value whose elements are provided by the indexed properties of _obj_. _elementTypes_ contains the names of ECMAScript Language Types that are allowed for element values of the List that is created.
+ - It is used to create a List value whose elements are provided by the indexed properties of _obj_. _validElementTypes_ indicates the types of values that are allowed as elements.
- 1. If _elementTypes_ is not present, set _elementTypes_ to « Undefined, Null, Boolean, String, Symbol, Number, BigInt, Object ».
+ 1. If _validElementTypes_ is not present, set _validElementTypes_ to ~all~.
1. If _obj_ is not an Object, throw a *TypeError* exception.
- 1. Let _len_ be ? LengthOfArrayLike(_obj_).
+ 1. Let _length_ be ? LengthOfArrayLike(_obj_).
1. Let _list_ be a new empty List.
1. Let _index_ be 0.
- 1. Repeat, while _index_ < _len_,
+ 1. Repeat, while _index_ < _length_,
1. Let _indexName_ be ! ToString(𝔽(_index_)).
1. Let _next_ be ? Get(_obj_, _indexName_).
- 1. If _elementTypes_ does not contain Type(_next_), throw a *TypeError* exception.
+ 1. If _validElementTypes_ is ~property-key~ and _next_ is not a property key, throw a *TypeError* exception.
1. Append _next_ to _list_.
1. Set _index_ to _index_ + 1.
1. Return _list_.
@@ -6433,67 +6525,67 @@
Invoke (
- _V_: an ECMAScript language value,
- _P_: a property key,
- optional _argumentsList_: a List of ECMAScript language values,
+ _value_: an ECMAScript language value,
+ _propertyKey_: a property key,
+ optional _argList_: a List of ECMAScript language values,
): either a normal completion containing an ECMAScript language value or a throw completion
- description
- - It is used to call a method property of an ECMAScript language value. _V_ serves as both the lookup point for the property and the *this* value of the call. _argumentsList_ is the list of arguments values passed to the method. If _argumentsList_ is not present, a new empty List is used as its value.
+ - It is used to call a method property of an ECMAScript language value. _value_ serves as both the lookup point for the property and the *this* value of the call. _argList_ is the list of arguments values passed to the method. If _argList_ is not present, a new empty List is used as its value.
- 1. If _argumentsList_ is not present, set _argumentsList_ to a new empty List.
- 1. Let _func_ be ? GetV(_V_, _P_).
- 1. Return ? Call(_func_, _V_, _argumentsList_).
+ 1. If _argList_ is not present, set _argList_ to a new empty List.
+ 1. Let _func_ be ? GetV(_value_, _propertyKey_).
+ 1. Return ? Call(_func_, _value_, _argList_).
OrdinaryHasInstance (
- _C_: an ECMAScript language value,
- _O_: an ECMAScript language value,
+ _ctor_: an ECMAScript language value,
+ _instance_: an ECMAScript language value,
): either a normal completion containing a Boolean or a throw completion
- description
- - It implements the default algorithm for determining if _O_ inherits from the instance object inheritance path provided by _C_.
+ - It implements the default algorithm for determining if _instance_ inherits from the instance object inheritance path provided by _ctor_.
- 1. If IsCallable(_C_) is *false*, return *false*.
- 1. If _C_ has a [[BoundTargetFunction]] internal slot, then
- 1. Let _BC_ be _C_.[[BoundTargetFunction]].
- 1. Return ? InstanceofOperator(_O_, _BC_).
- 1. If _O_ is not an Object, return *false*.
- 1. Let _P_ be ? Get(_C_, *"prototype"*).
- 1. If _P_ is not an Object, throw a *TypeError* exception.
+ 1. If IsCallable(_ctor_) is *false*, return *false*.
+ 1. If _ctor_ has a [[BoundTargetFunction]] internal slot, then
+ 1. Let _boundCtor_ be _ctor_.[[BoundTargetFunction]].
+ 1. Return ? InstanceofOperator(_instance_, _boundCtor_).
+ 1. If _instance_ is not an Object, return *false*.
+ 1. Let _proto_ be ? Get(_ctor_, *"prototype"*).
+ 1. If _proto_ is not an Object, throw a *TypeError* exception.
1. Repeat,
- 1. Set _O_ to ? _O_.[[GetPrototypeOf]] ().
- 1. If _O_ is *null*, return *false*.
- 1. If SameValue(_P_, _O_) is *true*, return *true*.
+ 1. Set _instance_ to ? _instance_.[[GetPrototypeOf]]() .
+ 1. If _instance_ is *null*, return *false*.
+ 1. If SameValue(_proto_, _instance_) is *true*, return *true*.
SpeciesConstructor (
- _O_: an Object,
- _defaultConstructor_: a constructor,
+ _obj_: an Object,
+ _defaultCtor_: a constructor,
): either a normal completion containing a constructor or a throw completion
- description
- - It is used to retrieve the constructor that should be used to create new objects that are derived from _O_. _defaultConstructor_ is the constructor to use if a constructor @@species property cannot be found starting from _O_.
+ - It is used to retrieve the constructor that should be used to create new objects that are derived from _obj_. _defaultCtor_ is the constructor to use if a constructor %Symbol.species% property cannot be found starting from _obj_.
- 1. Let _C_ be ? Get(_O_, *"constructor"*).
- 1. If _C_ is *undefined*, return _defaultConstructor_.
- 1. If _C_ is not an Object, throw a *TypeError* exception.
- 1. Let _S_ be ? Get(_C_, @@species).
- 1. If _S_ is either *undefined* or *null*, return _defaultConstructor_.
- 1. If IsConstructor(_S_) is *true*, return _S_.
+ 1. Let _ctor_ be ? Get(_obj_, *"constructor"*).
+ 1. If _ctor_ is *undefined*, return _defaultCtor_.
+ 1. If _ctor_ is not an Object, throw a *TypeError* exception.
+ 1. Let _species_ be ? Get(_ctor_, %Symbol.species%).
+ 1. If _species_ is either *undefined* or *null*, return _defaultCtor_.
+ 1. If IsConstructor(_species_) is *true*, return _species_.
1. Throw a *TypeError* exception.
@@ -6501,23 +6593,23 @@
EnumerableOwnProperties (
- _O_: an Object,
+ _obj_: an Object,
_kind_: ~key~, ~value~, or ~key+value~,
): either a normal completion containing a List of ECMAScript language values or a throw completion
- 1. Let _ownKeys_ be ? _O_.[[OwnPropertyKeys]] ().
+ 1. Let _ownKeys_ be ? _obj_.[[OwnPropertyKeys]]() .
1. Let _results_ be a new empty List.
1. For each element _key_ of _ownKeys_, do
1. If _key_ is a String, then
- 1. Let _desc_ be ? _O_.[[GetOwnProperty]] (_key_).
- 1. If _desc_ is not *undefined* and _desc_.[[Enumerable]] is *true*, then
+ 1. Let _propertyDesc_ be ? _obj_.[[GetOwnProperty]](_key_) .
+ 1. If _propertyDesc_ is not *undefined* and _propertyDesc_.[[Enumerable]] is *true*, then
1. If _kind_ is ~key~, then
1. Append _key_ to _results_.
1. Else,
- 1. Let _value_ be ? Get(_O_, _key_).
+ 1. Let _value_ be ? Get(_obj_, _key_).
1. If _kind_ is ~value~, then
1. Append _value_ to _results_.
1. Else,
@@ -6531,25 +6623,26 @@
GetFunctionRealm (
- _obj_: a function object,
+ _func_: a function object,
): either a normal completion containing a Realm Record or a throw completion
- 1. If _obj_ has a [[Realm]] internal slot, then
- 1. Return _obj_.[[Realm]].
- 1. If _obj_ is a bound function exotic object, then
- 1. Let _boundTargetFunction_ be _obj_.[[BoundTargetFunction]].
- 1. Return ? GetFunctionRealm(_boundTargetFunction_).
- 1. If _obj_ is a Proxy exotic object, then
- 1. Perform ? ValidateNonRevokedProxy(_obj_).
- 1. Let _proxyTarget_ be _obj_.[[ProxyTarget]].
+ 1. If _func_ has a [[Realm]] internal slot, then
+ 1. Return _func_.[[Realm]].
+ 1. If _func_ is a bound function exotic object, then
+ 1. Let _boundTargetFunc_ be _func_.[[BoundTargetFunction]].
+ 1. Return ? GetFunctionRealm(_boundTargetFunc_).
+ 1. If _func_ is a Proxy exotic object, then
+ 1. Perform ? ValidateNonRevokedProxy(_func_).
+ 1. Let _proxyTarget_ be _func_.[[ProxyTarget]].
+ 1. Assert: _proxyTarget_ is a function object.
1. Return ? GetFunctionRealm(_proxyTarget_).
1. [id="step-getfunctionrealm-default-return"] Return the current Realm Record.
- Step
+ Step
@@ -6566,17 +6659,17 @@
1. If _source_ is either *undefined* or *null*, return ~unused~.
1. Let _from_ be ! ToObject(_source_).
- 1. Let _keys_ be ? _from_.[[OwnPropertyKeys]] ().
+ 1. Let _keys_ be ? _from_.[[OwnPropertyKeys]]() .
1. For each element _nextKey_ of _keys_, do
1. Let _excluded_ be *false*.
- 1. For each element _e_ of _excludedItems_, do
- 1. If SameValue(_e_, _nextKey_) is *true*, then
+ 1. For each element _element_ of _excludedItems_, do
+ 1. If SameValue(_element_, _nextKey_) is *true*, then
1. Set _excluded_ to *true*.
1. If _excluded_ is *false*, then
- 1. Let _desc_ be ? _from_.[[GetOwnProperty]] (_nextKey_).
- 1. If _desc_ is not *undefined* and _desc_.[[Enumerable]] is *true*, then
- 1. Let _propValue_ be ? Get(_from_, _nextKey_).
- 1. Perform ! CreateDataPropertyOrThrow(_target_, _nextKey_, _propValue_).
+ 1. Let _propertyDesc_ be ? _from_.[[GetOwnProperty]](_nextKey_) .
+ 1. If _propertyDesc_ is not *undefined* and _propertyDesc_.[[Enumerable]] is *true*, then
+ 1. Let _propertyValue_ be ? Get(_from_, _nextKey_).
+ 1. Perform ! CreateDataPropertyOrThrow(_target_, _nextKey_, _propertyValue_).
1. Return ~unused~.
@@ -6587,15 +6680,15 @@
PrivateElementFind (
- _O_: an Object,
- _P_: a Private Name,
+ _obj_: an Object,
+ _privateName_: a Private Name,
): a PrivateElement or ~empty~
- 1. If _O_.[[PrivateElements]] contains a PrivateElement _pe_ such that _pe_.[[Key]] is _P_, then
- 1. Return _pe_.
+ 1. If _obj_.[[PrivateElements]] contains a PrivateElement _entry_ such that _entry_.[[Key]] is _privateName_, then
+ 1. Return _entry_.
1. Return ~empty~.
@@ -6603,8 +6696,8 @@
PrivateFieldAdd (
- _O_: an Object,
- _P_: a Private Name,
+ _obj_: an Object,
+ _privateName_: a Private Name,
_value_: an ECMAScript language value,
): either a normal completion containing ~unused~ or a throw completion
@@ -6612,10 +6705,10 @@
1. If the host is a web browser, then
- 1. Perform ? HostEnsureCanAddPrivateElement(_O_).
- 1. Let _entry_ be PrivateElementFind(_O_, _P_).
+ 1. Perform ? HostEnsureCanAddPrivateElement(_obj_).
+ 1. Let _entry_ be PrivateElementFind(_obj_, _privateName_).
1. If _entry_ is not ~empty~, throw a *TypeError* exception.
- 1. Append PrivateElement { [[Key]]: _P_, [[Kind]]: ~field~, [[Value]]: _value_ } to _O_.[[PrivateElements]].
+ 1. Append PrivateElement { [[Key]]: _privateName_, [[Kind]]: ~field~, [[Value]]: _value_ } to _obj_.[[PrivateElements]].
1. Return ~unused~.
@@ -6623,7 +6716,7 @@
PrivateMethodOrAccessorAdd (
- _O_: an Object,
+ _obj_: an Object,
_method_: a PrivateElement,
): either a normal completion containing ~unused~ or a throw completion
@@ -6632,10 +6725,10 @@
1. Assert: _method_.[[Kind]] is either ~method~ or ~accessor~.
1. If the host is a web browser, then
- 1. Perform ? HostEnsureCanAddPrivateElement(_O_).
- 1. Let _entry_ be PrivateElementFind(_O_, _method_.[[Key]]).
+ 1. Perform ? HostEnsureCanAddPrivateElement(_obj_).
+ 1. Let _entry_ be PrivateElementFind(_obj_, _method_.[[Key]]).
1. If _entry_ is not ~empty~, throw a *TypeError* exception.
- 1. Append _method_ to _O_.[[PrivateElements]].
+ 1. Append _method_ to _obj_.[[PrivateElements]].
1. Return ~unused~.
@@ -6646,7 +6739,7 @@
HostEnsureCanAddPrivateElement (
- _O_: an Object,
+ _obj_: an Object,
): either a normal completion containing ~unused~ or a throw completion
@@ -6655,7 +6748,7 @@
An implementation of HostEnsureCanAddPrivateElement must conform to the following requirements:
- - If _O_ is not a host-defined exotic object, this abstract operation must return NormalCompletion(~unused~) and perform no other steps.
+ - If _obj_ is not a host-defined exotic object, this abstract operation must return NormalCompletion(~unused~) and perform no other steps.
- Any two calls of this abstract operation with the same argument must return the same kind of Completion Record.
The default implementation of HostEnsureCanAddPrivateElement is to return NormalCompletion(~unused~).
@@ -6665,46 +6758,45 @@
PrivateGet (
- _O_: an Object,
- _P_: a Private Name,
+ _obj_: an Object,
+ _privateName_: a Private Name,
): either a normal completion containing an ECMAScript language value or a throw completion
- 1. Let _entry_ be PrivateElementFind(_O_, _P_).
+ 1. Let _entry_ be PrivateElementFind(_obj_, _privateName_).
1. If _entry_ is ~empty~, throw a *TypeError* exception.
1. If _entry_.[[Kind]] is either ~field~ or ~method~, then
1. Return _entry_.[[Value]].
1. Assert: _entry_.[[Kind]] is ~accessor~.
- 1. If _entry_.[[Get]] is *undefined*, throw a *TypeError* exception.
- 1. Let _getter_ be _entry_.[[Get]].
- 1. Return ? Call(_getter_, _O_).
+ 1. If _entry_.[[Getter]] is *undefined*, throw a *TypeError* exception.
+ 1. Let _getter_ be _entry_.[[Getter]].
+ 1. Return ? Call(_getter_, _obj_).
PrivateSet (
- _O_: an Object,
- _P_: a Private Name,
+ _obj_: an Object,
+ _privateName_: a Private Name,
_value_: an ECMAScript language value,
): either a normal completion containing ~unused~ or a throw completion
- 1. Let _entry_ be PrivateElementFind(_O_, _P_).
+ 1. Let _entry_ be PrivateElementFind(_obj_, _privateName_).
1. If _entry_ is ~empty~, throw a *TypeError* exception.
+ 1. If _entry_.[[Kind]] is ~method~, throw a *TypeError* exception.
1. If _entry_.[[Kind]] is ~field~, then
1. Set _entry_.[[Value]] to _value_.
- 1. Else if _entry_.[[Kind]] is ~method~, then
- 1. Throw a *TypeError* exception.
1. Else,
1. Assert: _entry_.[[Kind]] is ~accessor~.
- 1. If _entry_.[[Set]] is *undefined*, throw a *TypeError* exception.
- 1. Let _setter_ be _entry_.[[Set]].
- 1. Perform ? Call(_setter_, _O_, « _value_ »).
+ 1. If _entry_.[[Setter]] is *undefined*, throw a *TypeError* exception.
+ 1. Let _setter_ be _entry_.[[Setter]].
+ 1. Perform ? Call(_setter_, _obj_, « _value_ »).
1. Return ~unused~.
@@ -6737,19 +6829,19 @@
InitializeInstanceElements (
- _O_: an Object,
- _constructor_: an ECMAScript function object,
+ _obj_: an Object,
+ _ctor_: an ECMAScript function object or a built-in function object,
): either a normal completion containing ~unused~ or a throw completion
- 1. Let _methods_ be the value of _constructor_.[[PrivateMethods]].
+ 1. Let _methods_ be _ctor_.[[PrivateMethods]].
1. For each PrivateElement _method_ of _methods_, do
- 1. Perform ? PrivateMethodOrAccessorAdd(_O_, _method_).
- 1. Let _fields_ be the value of _constructor_.[[Fields]].
+ 1. Perform ? PrivateMethodOrAccessorAdd(_obj_, _method_).
+ 1. Let _fields_ be _ctor_.[[Fields]].
1. For each element _fieldRecord_ of _fields_, do
- 1. Perform ? DefineField(_O_, _fieldRecord_).
+ 1. Perform ? DefineField(_obj_, _fieldRecord_).
1. Return ~unused~.
@@ -6765,10 +6857,10 @@
- 1. For each Record { [[Key]], [[Elements]] } _g_ of _groups_, do
- 1. If SameValue(_g_.[[Key]], _key_) is *true*, then
+ 1. For each Record { [[Key]], [[Elements]] } _group_ of _groups_, do
+ 1. If SameValue(_group_.[[Key]], _key_) is *true*, then
1. Assert: Exactly one element of _groups_ meets this criterion.
- 1. Append _value_ to _g_.[[Elements]].
+ 1. Append _value_ to _group_.[[Elements]].
1. Return ~unused~.
1. Let _group_ be the Record { [[Key]]: _key_, [[Elements]]: « _value_ » }.
1. Append _group_ to _groups_.
@@ -6780,15 +6872,15 @@
GroupBy (
_items_: an ECMAScript language value,
- _callbackfn_: an ECMAScript language value,
- _keyCoercion_: ~property~ or ~zero~,
+ _callback_: an ECMAScript language value,
+ _keyCoercion_: ~property~ or ~collection~,
): either a normal completion containing a List of Records with fields [[Key]] (an ECMAScript language value) and [[Elements]] (a List of ECMAScript language values), or a throw completion
1. Perform ? RequireObjectCoercible(_items_).
- 1. If IsCallable(_callbackfn_) is *false*, throw a *TypeError* exception.
+ 1. If IsCallable(_callback_) is *false*, throw a *TypeError* exception.
1. Let _groups_ be a new empty List.
1. Let _iteratorRecord_ be ? GetIterator(_items_, ~sync~).
1. Let _k_ be 0.
@@ -6800,18 +6892,61 @@
1. If _next_ is ~done~, then
1. Return _groups_.
1. Let _value_ be _next_.
- 1. Let _key_ be Completion(Call(_callbackfn_, *undefined*, « _value_, 𝔽(_k_) »)).
+ 1. Let _key_ be Completion(Call(_callback_, *undefined*, « _value_, 𝔽(_k_) »)).
1. IfAbruptCloseIterator(_key_, _iteratorRecord_).
1. If _keyCoercion_ is ~property~, then
1. Set _key_ to Completion(ToPropertyKey(_key_)).
1. IfAbruptCloseIterator(_key_, _iteratorRecord_).
1. Else,
- 1. Assert: _keyCoercion_ is ~zero~.
- 1. If _key_ is *-0*𝔽, set _key_ to *+0*𝔽.
+ 1. Assert: _keyCoercion_ is ~collection~.
+ 1. Set _key_ to CanonicalizeKeyedCollectionKey(_key_).
1. Perform AddValueToKeyedGroup(_groups_, _key_, _value_).
1. Set _k_ to _k_ + 1.
+
+
+
+ GetOptionsObject (
+ _options_: an ECMAScript language value,
+ ): either a normal completion containing an Object or a throw completion
+
+
+
+
+ 1. If _options_ is *undefined*, then
+ 1. Return OrdinaryObjectCreate(*null*).
+ 1. If _options_ is an Object, then
+ 1. Return _options_.
+ 1. Throw a *TypeError* exception.
+
+
+
+
+
+ SetterThatIgnoresPrototypeProperties (
+ _thisValue_: an ECMAScript language value,
+ _home_: an Object,
+ _propertyKey_: a property key,
+ _value_: an ECMAScript language value,
+ ): either a normal completion containing ~unused~ or a throw completion
+
+
+
+
+ 1. If _thisValue_ is not an Object, then
+ 1. Throw a *TypeError* exception.
+ 1. If SameValue(_thisValue_, _home_) is *true*, then
+ 1. NOTE: Throwing here emulates assignment to a non-writable data property on the _home_ object in strict mode code.
+ 1. Throw a *TypeError* exception.
+ 1. Let _propertyDesc_ be ? _thisValue_.[[GetOwnProperty]](_propertyKey_).
+ 1. If _propertyDesc_ is *undefined*, then
+ 1. Perform ? CreateDataPropertyOrThrow(_thisValue_, _propertyKey_, _value_).
+ 1. Else,
+ 1. Perform ? Set(_thisValue_, _propertyKey_, _value_, *true*).
+ 1. Return ~unused~.
+
+
@@ -6820,21 +6955,23 @@ Operations on Iterator Objects
Iterator Records
- An Iterator Record is a Record value used to encapsulate an Iterator or AsyncIterator along with the `next` method.
+ An Iterator Record is a Record used to encapsulate an iterator or async iterator along with the `next` method.
Iterator Records have the fields listed in
-
-
- Field Name
-
-
- Value
-
-
- Meaning
-
-
+
+
+
+ Field Name
+
+
+ Value
+
+
+ Meaning
+
+
+
[[Iterator]]
@@ -6843,7 +6980,7 @@ Iterator Records
an Object
- An object that conforms to the Iterator or AsyncIterator interface.
+ An object that conforms to the iterator interface or the async iterator interface.
@@ -6872,6 +7009,21 @@ Iterator Records
+
+
+ GetIteratorDirect (
+ _obj_: an Object,
+ ): either a normal completion containing an Iterator Record or a throw completion
+
+
+
+
+ 1. Let _nextMethod_ be ? Get(_obj_, *"next"*).
+ 1. Let _iteratorRecord_ be the Iterator Record { [[Iterator]]: _obj_, [[NextMethod]]: _nextMethod_, [[Done]]: *false* }.
+ 1. Return _iteratorRecord_.
+
+
+
GetIteratorFromMethod (
@@ -6884,9 +7036,7 @@
1. Let _iterator_ be ? Call(_method_, _obj_).
1. If _iterator_ is not an Object, throw a *TypeError* exception.
- 1. Let _nextMethod_ be ? Get(_iterator_, *"next"*).
- 1. Let _iteratorRecord_ be the Iterator Record { [[Iterator]]: _iterator_, [[NextMethod]]: _nextMethod_, [[Done]]: *false* }.
- 1. Return _iteratorRecord_.
+ 1. Return ? GetIteratorDirect(_iterator_).
@@ -6901,19 +7051,43 @@
1. If _kind_ is ~async~, then
- 1. Let _method_ be ? GetMethod(_obj_, @@asyncIterator).
+ 1. Let _method_ be ? GetMethod(_obj_, %Symbol.asyncIterator%).
1. If _method_ is *undefined*, then
- 1. Let _syncMethod_ be ? GetMethod(_obj_, @@iterator).
+ 1. Let _syncMethod_ be ? GetMethod(_obj_, %Symbol.iterator%).
1. If _syncMethod_ is *undefined*, throw a *TypeError* exception.
1. Let _syncIteratorRecord_ be ? GetIteratorFromMethod(_obj_, _syncMethod_).
1. Return CreateAsyncFromSyncIterator(_syncIteratorRecord_).
1. Else,
- 1. Let _method_ be ? GetMethod(_obj_, @@iterator).
+ 1. Let _method_ be ? GetMethod(_obj_, %Symbol.iterator%).
1. If _method_ is *undefined*, throw a *TypeError* exception.
1. Return ? GetIteratorFromMethod(_obj_, _method_).
+
+
+ GetIteratorFlattenable (
+ _obj_: an ECMAScript language value,
+ _primitiveHandling_: ~iterate-string-primitives~ or ~reject-primitives~,
+ ): either a normal completion containing an Iterator Record or a throw completion
+
+
+
+
+ 1. If _obj_ is not an Object, then
+ 1. If _primitiveHandling_ is ~reject-primitives~, throw a *TypeError* exception.
+ 1. Assert: _primitiveHandling_ is ~iterate-string-primitives~.
+ 1. If _obj_ is not a String, throw a *TypeError* exception.
+ 1. Let _method_ be ? GetMethod(_obj_, %Symbol.iterator%).
+ 1. If _method_ is *undefined*, then
+ 1. Let _iterator_ be _obj_.
+ 1. Else,
+ 1. Let _iterator_ be ? Call(_method_, _obj_).
+ 1. If _iterator_ is not an Object, throw a *TypeError* exception.
+ 1. Return ? GetIteratorDirect(_iterator_).
+
+
+
IteratorNext (
@@ -6942,26 +7116,26 @@
IteratorComplete (
- _iterResult_: an Object,
+ _iteratorResult_: an Object,
): either a normal completion containing a Boolean or a throw completion
- 1. Return ToBoolean(? Get(_iterResult_, *"done"*)).
+ 1. Return ToBoolean(? Get(_iteratorResult_, *"done"*)).
IteratorValue (
- _iterResult_: an Object,
+ _iteratorResult_: an Object,
): either a normal completion containing an ECMAScript language value or a throw completion
- 1. Return ? Get(_iterResult_, *"value"*).
+ 1. Return ? Get(_iteratorResult_, *"value"*).
@@ -7036,6 +7210,24 @@
+
+
+ IteratorCloseAll (
+ _iterators_: a List of Iterator Records,
+ _completion_: a Completion Record,
+ ): a Completion Record
+
+
+ - skip global checks
+ - true
+
+
+ 1. For each element _iterator_ of _iterators_, in reverse List order, do
+ 1. Set _completion_ to Completion(IteratorClose(_iterator_, _completion_)).
+ 1. Return ? _completion_.
+
+
+
IfAbruptCloseIterator ( _value_, _iteratorRecord_ )
IfAbruptCloseIterator is a shorthand for a sequence of algorithm steps that use an Iterator Record. An algorithm step of the form:
@@ -7046,7 +7238,21 @@ IfAbruptCloseIterator ( _value_, _iteratorRecord_ )
1. Assert: _value_ is a Completion Record.
1. If _value_ is an abrupt completion, return ? IteratorClose(_iteratorRecord_, _value_).
- 1. Else, set _value_ to ! _value_.
+ 1. Set _value_ to ! _value_.
+
+
+
+
+ IfAbruptCloseIterators ( _value_, _iteratorRecords_ )
+ IfAbruptCloseIterators is a shorthand for a sequence of algorithm steps that use a list of Iterator Records. An algorithm step of the form:
+
+ 1. IfAbruptCloseIterators(_value_, _iteratorRecords_).
+
+ means the same thing as:
+
+ 1. Assert: _value_ is a Completion Record.
+ 1. If _value_ is an abrupt completion, return ? IteratorCloseAll(_iteratorRecords_, _value_).
+ 1. Set _value_ to ! _value_.
@@ -7077,16 +7283,30 @@
+
+ IfAbruptCloseAsyncIterator ( _value_, _iteratorRecord_ )
+ IfAbruptCloseAsyncIterator is a shorthand for a sequence of algorithm steps that use an Iterator Record. An algorithm step of the form:
+
+ 1. IfAbruptCloseAsyncIterator(_value_, _iteratorRecord_).
+
+ means the same thing as:
+
+ 1. Assert: _value_ is a Completion Record.
+ 1. If _value_ is an abrupt completion, return ? AsyncIteratorClose(_iteratorRecord_, _value_).
+ 1. Set _value_ to ! _value_.
+
+
+
- CreateIterResultObject (
+ CreateIteratorResultObject (
_value_: an ECMAScript language value,
_done_: a Boolean,
- ): an Object that conforms to the IteratorResult interface
+ ): an Object that conforms to the IteratorResult interface
- description
- - It creates an object that conforms to the IteratorResult interface.
+ - It creates an object that conforms to the IteratorResult interface.
1. Let _obj_ be OrdinaryObjectCreate(%Object.prototype%).
@@ -7104,15 +7324,15 @@
- description
- - It creates an Iterator (
+ - It creates an Iterator Record whose [[NextMethod]] returns the successive elements of _list_.
1. Let _closure_ be a new Abstract Closure with no parameters that captures _list_ and performs the following steps when called:
- 1. For each element _E_ of _list_, do
- 1. Perform ? GeneratorYield(CreateIterResultObject(_E_, *false*)).
+ 1. For each element _value_ of _list_, do
+ 1. Perform ? GeneratorYield(CreateIteratorResultObject(_value_, *false*)).
1. Return NormalCompletion(*undefined*).
- 1. Let _iterator_ be CreateIteratorFromClosure(_closure_, ~empty~, %IteratorPrototype%).
- 1. Return the Iterator Record { [[Iterator]]: _iterator_, [[NextMethod]]: %GeneratorFunction.prototype.prototype.next%, [[Done]]: *false* }.
+ 1. Let _iterator_ be CreateIteratorFromClosure(_closure_, ~empty~, %Iterator.prototype%).
+ 1. Return the Iterator Record { [[Iterator]]: _iterator_, [[NextMethod]]: %GeneratorPrototype.next%, [[Done]]: *false* }.
The list iterator object is never directly accessible to ECMAScript code.
@@ -7137,6 +7357,186 @@
+
+
+ Operations on Disposable Objects
+ See Common Resource Management Interfaces (
+
+
+ DisposableResource Records
+ A DisposableResource Record is a Record value used to encapsulate a disposable object along with the method used to dispose the object. DisposableResource Records are produced by the CreateDisposableResource abstract operation.
+ DisposableResource Records have the fields listed in
+
+
+
+
+ Field Name
+
+
+ Value
+
+
+ Meaning
+
+
+
+
+ [[ResourceValue]]
+
+
+ an Object or *undefined*
+
+
+ The value to be disposed.
+
+
+
+
+ [[Kind]]
+
+
+ ~sync-dispose~ or ~async-dispose~
+
+
+ Indicates whether the resource was added by a `using` declaration or DisposableStack object (~sync-dispose~) or by an `await using` declaration or AsyncDisposableStack object (~async-dispose~).
+
+
+
+
+ [[DisposeMethod]]
+
+
+ a function object or *undefined*
+
+
+ A function object that will be called with [[ResourceValue]] as its *this* value when the resource is disposed.
+
+
+
+
+
+
+
+
+ AddDisposableResource (
+ _disposableResourceStack_: a List of DisposableResource Records,
+ _value_: an ECMAScript language value,
+ _kind_: ~sync-dispose~ or ~async-dispose~,
+ optional _method_: a function object,
+ ): either a normal completion containing ~unused~ or a throw completion
+
+
+
+
+ 1. If _method_ is present, then
+ 1. Assert: _value_ is *undefined*.
+ 1. Let _resource_ be ? CreateDisposableResource(*undefined*, _kind_, _method_).
+ 1. Else,
+ 1. If _value_ is either *null* or *undefined* and _kind_ is ~sync-dispose~, return ~unused~.
+ 1. NOTE: When _value_ is either *null* or *undefined* and _kind_ is ~async-dispose~, we record that the resource was evaluated to ensure we will still perform an Await when resources are later disposed.
+ 1. Let _resource_ be ? CreateDisposableResource(_value_, _kind_).
+ 1. Append _resource_ to _disposableResourceStack_.
+ 1. Return ~unused~.
+
+
+
+
+
+ CreateDisposableResource (
+ _value_: an ECMAScript language value,
+ _kind_: ~sync-dispose~ or ~async-dispose~,
+ optional _method_: a function object,
+ ): either a normal completion containing a DisposableResource Record or a throw completion
+
+
+
+
+ 1. If _method_ is not present, then
+ 1. If _value_ is either *null* or *undefined*, then
+ 1. Set _value_ to *undefined*.
+ 1. Set _method_ to *undefined*.
+ 1. Else,
+ 1. Set _method_ to ? GetDisposeMethod(_value_, _kind_).
+ 1. If _method_ is *undefined*, throw a *TypeError* exception.
+ 1. Return the DisposableResource Record { [[ResourceValue]]: _value_, [[Kind]]: _kind_, [[DisposeMethod]]: _method_ }.
+
+
+
+
+
+ GetDisposeMethod (
+ _value_: an ECMAScript language value,
+ _kind_: ~sync-dispose~ or ~async-dispose~,
+ ): either a normal completion containing either a function object or *undefined*, or a throw completion
+
+
+
+
+ 1. If _value_ is not an Object, throw a *TypeError* exception.
+ 1. If _kind_ is ~sync-dispose~, return ? GetMethod(_value_, %Symbol.dispose%).
+ 1. Assert: _kind_ is ~async-dispose~.
+ 1. Let _asyncMethod_ be ? GetMethod(_value_, %Symbol.asyncDispose%).
+ 1. If _asyncMethod_ is not *undefined*, return _asyncMethod_.
+ 1. Let _syncMethod_ be ? GetMethod(_value_, %Symbol.dispose%).
+ 1. If _syncMethod_ is *undefined*, return *undefined*.
+ 1. Let _closure_ be a new Abstract Closure with no parameters that captures _syncMethod_ and performs the following steps when called:
+ 1. Let _obj_ be the *this* value.
+ 1. Let _promiseCapability_ be ! NewPromiseCapability(%Promise%).
+ 1. Let _result_ be Completion(Call(_syncMethod_, _obj_)).
+ 1. IfAbruptRejectPromise(_result_, _promiseCapability_).
+ 1. Perform ! Call(_promiseCapability_.[[Resolve]], *undefined*, « *undefined* »).
+ 1. Return _promiseCapability_.[[Promise]].
+ 1. NOTE: This function is not observable to user code. It is used to ensure that a Promise returned from a synchronous `%Symbol.dispose%` method will not be awaited and that a synchronous exception will be translated to a rejected Promise.
+ 1. Return CreateBuiltinFunction(_closure_, 0, *""*, « »).
+
+
+
+
+
+ DisposeResources (
+ _disposableResourceStack_: a List of DisposableResource Records,
+ _completion_: either a normal completion containing either an ECMAScript language value or ~empty~, or an abrupt completion,
+ ): either a normal completion containing either an ECMAScript language value or ~empty~, or an abrupt completion
+
+
+
+
+ 1. Let _needsAwait_ be *false*.
+ 1. Let _hasAwaited_ be *false*.
+ 1. Let _outputCompletion_ be _completion_.
+ 1. For each element _resource_ of _disposableResourceStack_, in reverse List order, do
+ 1. Let _value_ be _resource_.[[ResourceValue]].
+ 1. Let _kind_ be _resource_.[[Kind]].
+ 1. Let _method_ be _resource_.[[DisposeMethod]].
+ 1. If _kind_ is ~sync-dispose~, _needsAwait_ is *true*, and _hasAwaited_ is *false*, then
+ 1. Perform ! Await(*undefined*).
+ 1. Set _needsAwait_ to *false*.
+ 1. If _method_ is not *undefined*, then
+ 1. Let _result_ be Completion(Call(_method_, _value_)).
+ 1. If _result_ is a normal completion and _kind_ is ~async-dispose~, then
+ 1. Set _result_ to Completion(Await(_result_.[[Value]])).
+ 1. Set _hasAwaited_ to *true*.
+ 1. If _result_ is a throw completion, then
+ 1. If _outputCompletion_ is a throw completion, then
+ 1. Set _result_ to _result_.[[Value]].
+ 1. Let _suppressed_ be _outputCompletion_.[[Value]].
+ 1. Let _error_ be a newly created *SuppressedError* object.
+ 1. Perform CreateNonEnumerableDataPropertyOrThrow(_error_, *"error"*, _result_).
+ 1. Perform CreateNonEnumerableDataPropertyOrThrow(_error_, *"suppressed"*, _suppressed_).
+ 1. Set _outputCompletion_ to ThrowCompletion(_error_).
+ 1. Else,
+ 1. Set _outputCompletion_ to _result_.
+ 1. Else,
+ 1. Assert: _kind_ is ~async-dispose~.
+ 1. Set _needsAwait_ to *true*.
+ 1. NOTE: This can only indicate a case where either *null* or *undefined* was the initialized value of an `await using` declaration.
+ 1. If _needsAwait_ is *true* and _hasAwaited_ is *false*, then
+ 1. Perform ! Await(*undefined*).
+ 1. NOTE: At this point _disposableResourceStack_ will never be used again. The contents of _disposableResourceStack_ can be discarded in implementations, such as by garbage collection.
+ 1. Return ? _outputCompletion_.
+
+
+
@@ -7150,7 +7550,7 @@ Runtime Semantics: Evaluation ( ): a Completion Record
- user-code
- The definitions for this operation are distributed over the "ECMAScript Language" sections of this specification. Each definition appears after the defining occurrence of the relevant productions.
+ The definitions for this operation are distributed over the “ECMAScript Language” sections of this specification. Each definition appears after the defining occurrence of the relevant productions.
@@ -7180,6 +7580,16 @@ Static Semantics: BoundNames ( ): a List of Strings
1. Return the BoundNames of |BindingList|.
+
+ UsingDeclaration :
+ `using` BindingList `;`
+
+ AwaitUsingDeclaration :
+ CoverAwaitExpressionAndAwaitUsingDeclarationHead BindingList `;`
+
+
+ 1. Return the BoundNames of |BindingList|.
+
BindingList : BindingList `,` LexicalBinding
1. Let _names1_ be the BoundNames of |BindingList|.
@@ -7340,11 +7750,11 @@ Static Semantics: BoundNames ( ): a List of Strings
1. Let _head_ be the |AsyncArrowHead| that is covered by |CoverCallExpressionAndAsyncArrowHead|.
1. Return the BoundNames of _head_.
- ImportDeclaration : `import` ImportClause FromClause `;`
+ ImportDeclaration : `import` ImportClause FromClause WithClause? `;`
1. Return the BoundNames of |ImportClause|.
- ImportDeclaration : `import` ModuleSpecifier `;`
+ ImportDeclaration : `import` ModuleSpecifier WithClause? `;`
1. Return a new empty List.
@@ -7376,7 +7786,7 @@ Static Semantics: BoundNames ( ): a List of Strings
ExportDeclaration :
- `export` ExportFromClause FromClause `;`
+ `export` ExportFromClause FromClause WithClause? `;`
`export` NamedExports `;`
@@ -7392,15 +7802,15 @@ Static Semantics: BoundNames ( ): a List of Strings
ExportDeclaration : `export` `default` HoistableDeclaration
- 1. Let _declarationNames_ be the BoundNames of |HoistableDeclaration|.
- 1. If _declarationNames_ does not include the element *"\*default\*"*, append *"\*default\*"* to _declarationNames_.
- 1. Return _declarationNames_.
+ 1. Let _declNames_ be the BoundNames of |HoistableDeclaration|.
+ 1. If _declNames_ does not include the element *"\*default\*"*, append *"\*default\*"* to _declNames_.
+ 1. Return _declNames_.
ExportDeclaration : `export` `default` ClassDeclaration
- 1. Let _declarationNames_ be the BoundNames of |ClassDeclaration|.
- 1. If _declarationNames_ does not include the element *"\*default\*"*, append *"\*default\*"* to _declarationNames_.
- 1. Return _declarationNames_.
+ 1. Let _declNames_ be the BoundNames of |ClassDeclaration|.
+ 1. If _declNames_ does not include the element *"\*default\*"*, append *"\*default\*"* to _declNames_.
+ 1. Return _declNames_.
ExportDeclaration : `export` `default` AssignmentExpression `;`
@@ -7454,6 +7864,16 @@ Static Semantics: IsConstantDeclaration ( ): a Boolean
1. Return *true*.
+
+ UsingDeclaration :
+ `using` BindingList `;`
+
+ AwaitUsingDeclaration :
+ CoverAwaitExpressionAndAwaitUsingDeclarationHead BindingList `;`
+
+
+ 1. Return *true*.
+
FunctionDeclaration :
`function` BindingIdentifier `(` FormalParameters `)` `{` FunctionBody `}`
@@ -7496,6 +7916,124 @@ Static Semantics: IsConstantDeclaration ( ): a Boolean
+
+ Static Semantics: IsUsingDeclaration ( ): a Boolean
+
+
+ LexicalDeclaration : LetOrConst BindingList `;`
+
+ 1. Return *false*.
+
+
+ UsingDeclaration :
+ `using` BindingList `;`
+
+ AwaitUsingDeclaration :
+ CoverAwaitExpressionAndAwaitUsingDeclarationHead BindingList `;`
+
+
+ 1. Return *true*.
+
+ ForDeclaration : LetOrConst ForBinding
+
+ 1. Return *false*.
+
+
+ ForDeclaration :
+ `using` ForBinding
+ `await` `using` ForBinding
+
+
+ 1. Return *true*.
+
+
+ FunctionDeclaration :
+ `function` BindingIdentifier `(` FormalParameters `)` `{` FunctionBody `}`
+ `function` `(` FormalParameters `)` `{` FunctionBody `}`
+
+ GeneratorDeclaration :
+ `function` `*` BindingIdentifier `(` FormalParameters `)` `{` GeneratorBody `}`
+ `function` `*` `(` FormalParameters `)` `{` GeneratorBody `}`
+
+ AsyncGeneratorDeclaration :
+ `async` `function` `*` BindingIdentifier `(` FormalParameters `)` `{` AsyncGeneratorBody `}`
+ `async` `function` `*` `(` FormalParameters `)` `{` AsyncGeneratorBody `}`
+
+ AsyncFunctionDeclaration :
+ `async` `function` BindingIdentifier `(` FormalParameters `)` `{` AsyncFunctionBody `}`
+ `async` `function` `(` FormalParameters `)` `{` AsyncFunctionBody `}`
+
+
+ 1. Return *false*.
+
+
+ ClassDeclaration :
+ `class` BindingIdentifier ClassTail
+ `class` ClassTail
+
+
+ 1. Return *false*.
+
+
+
+
+ Static Semantics: IsAwaitUsingDeclaration ( ): a Boolean
+
+
+ LexicalDeclaration : LetOrConst BindingList `;`
+
+ 1. Return *false*.
+
+ UsingDeclaration : `using` BindingList `;`
+
+ 1. Return *false*.
+
+ AwaitUsingDeclaration : CoverAwaitExpressionAndAwaitUsingDeclarationHead BindingList `;`
+
+ 1. Return *true*.
+
+ ForDeclaration : LetOrConst ForBinding
+
+ 1. Return *false*.
+
+ ForDeclaration : `using` ForBinding
+
+ 1. Return *false*.
+
+ ForDeclaration : `await` `using` ForBinding
+
+ 1. Return *true*.
+
+
+ FunctionDeclaration :
+ `function` BindingIdentifier `(` FormalParameters `)` `{` FunctionBody `}`
+ `function` `(` FormalParameters `)` `{` FunctionBody `}`
+
+ GeneratorDeclaration :
+ `function` `*` BindingIdentifier `(` FormalParameters `)` `{` GeneratorBody `}`
+ `function` `*` `(` FormalParameters `)` `{` GeneratorBody `}`
+
+ AsyncGeneratorDeclaration :
+ `async` `function` `*` BindingIdentifier `(` FormalParameters `)` `{` AsyncGeneratorBody `}`
+ `async` `function` `*` `(` FormalParameters `)` `{` AsyncGeneratorBody `}`
+
+ AsyncFunctionDeclaration :
+ `async` `function` BindingIdentifier `(` FormalParameters `)` `{` AsyncFunctionBody `}`
+ `async` `function` `(` FormalParameters `)` `{` AsyncFunctionBody `}`
+
+
+ 1. Return *false*.
+
+
+ ClassDeclaration :
+ `class` BindingIdentifier ClassTail
+ `class` ClassTail
+
+
+ 1. Return *false*.
+
+
+
Static Semantics: LexicallyDeclaredNames ( ): a List of Strings
@@ -7630,9 +8168,9 @@ Static Semantics: LexicallyScopedDeclarations ( ): a List of Parse Nodes
StatementList : StatementList StatementListItem
- 1. Let _declarations1_ be the LexicallyScopedDeclarations of |StatementList|.
- 1. Let _declarations2_ be the LexicallyScopedDeclarations of |StatementListItem|.
- 1. Return the list-concatenation of _declarations1_ and _declarations2_.
+ 1. Let _decls1_ be the LexicallyScopedDeclarations of |StatementList|.
+ 1. Let _decls2_ be the LexicallyScopedDeclarations of |StatementListItem|.
+ 1. Return the list-concatenation of _decls1_ and _decls2_.
StatementListItem : Statement
@@ -7649,18 +8187,18 @@ Static Semantics: LexicallyScopedDeclarations ( ): a List of Parse Nodes
CaseBlock : `{` CaseClauses? DefaultClause CaseClauses? `}`
- 1. If the first |CaseClauses| is present, let _declarations1_ be the LexicallyScopedDeclarations of the first |CaseClauses|.
- 1. Else, let _declarations1_ be a new empty List.
- 1. Let _declarations2_ be the LexicallyScopedDeclarations of |DefaultClause|.
- 1. If the second |CaseClauses| is present, let _declarations3_ be the LexicallyScopedDeclarations of the second |CaseClauses|.
- 1. Else, let _declarations3_ be a new empty List.
- 1. Return the list-concatenation of _declarations1_, _declarations2_, and _declarations3_.
+ 1. If the first |CaseClauses| is present, let _decls1_ be the LexicallyScopedDeclarations of the first |CaseClauses|.
+ 1. Else, let _decls1_ be a new empty List.
+ 1. Let _decls2_ be the LexicallyScopedDeclarations of |DefaultClause|.
+ 1. If the second |CaseClauses| is present, let _decls3_ be the LexicallyScopedDeclarations of the second |CaseClauses|.
+ 1. Else, let _decls3_ be a new empty List.
+ 1. Return the list-concatenation of _decls1_, _decls2_, and _decls3_.
CaseClauses : CaseClauses CaseClause
- 1. Let _declarations1_ be the LexicallyScopedDeclarations of |CaseClauses|.
- 1. Let _declarations2_ be the LexicallyScopedDeclarations of |CaseClause|.
- 1. Return the list-concatenation of _declarations1_ and _declarations2_.
+ 1. Let _decls1_ be the LexicallyScopedDeclarations of |CaseClauses|.
+ 1. Let _decls2_ be the LexicallyScopedDeclarations of |CaseClause|.
+ 1. Return the list-concatenation of _decls1_ and _decls2_.
CaseClause : `case` Expression `:` StatementList?
@@ -7724,9 +8262,9 @@ Static Semantics: LexicallyScopedDeclarations ( ): a List of Parse Nodes
ModuleItemList : ModuleItemList ModuleItem
- 1. Let _declarations1_ be the LexicallyScopedDeclarations of |ModuleItemList|.
- 1. Let _declarations2_ be the LexicallyScopedDeclarations of |ModuleItem|.
- 1. Return the list-concatenation of _declarations1_ and _declarations2_.
+ 1. Let _decls1_ be the LexicallyScopedDeclarations of |ModuleItemList|.
+ 1. Let _decls2_ be the LexicallyScopedDeclarations of |ModuleItem|.
+ 1. Return the list-concatenation of _decls1_ and _decls2_.
ModuleItem : ImportDeclaration
@@ -7734,7 +8272,7 @@ Static Semantics: LexicallyScopedDeclarations ( ): a List of Parse Nodes
ExportDeclaration :
- `export` ExportFromClause FromClause `;`
+ `export` ExportFromClause FromClause WithClause? `;`
`export` NamedExports `;`
`export` VariableStatement
@@ -7994,9 +8532,9 @@ Static Semantics: VarScopedDeclarations ( ): a List of Parse Nodes
StatementList : StatementList StatementListItem
- 1. Let _declarations1_ be the VarScopedDeclarations of |StatementList|.
- 1. Let _declarations2_ be the VarScopedDeclarations of |StatementListItem|.
- 1. Return the list-concatenation of _declarations1_ and _declarations2_.
+ 1. Let _decls1_ be the VarScopedDeclarations of |StatementList|.
+ 1. Let _decls2_ be the VarScopedDeclarations of |StatementListItem|.
+ 1. Return the list-concatenation of _decls1_ and _decls2_.
StatementListItem : Declaration
@@ -8008,14 +8546,14 @@ Static Semantics: VarScopedDeclarations ( ): a List of Parse Nodes
VariableDeclarationList : VariableDeclarationList `,` VariableDeclaration
- 1. Let _declarations1_ be the VarScopedDeclarations of |VariableDeclarationList|.
- 1. Return the list-concatenation of _declarations1_ and « |VariableDeclaration| ».
+ 1. Let _decls1_ be the VarScopedDeclarations of |VariableDeclarationList|.
+ 1. Return the list-concatenation of _decls1_ and « |VariableDeclaration| ».
IfStatement : `if` `(` Expression `)` Statement `else` Statement
- 1. Let _declarations1_ be the VarScopedDeclarations of the first |Statement|.
- 1. Let _declarations2_ be the VarScopedDeclarations of the second |Statement|.
- 1. Return the list-concatenation of _declarations1_ and _declarations2_.
+ 1. Let _decls1_ be the VarScopedDeclarations of the first |Statement|.
+ 1. Let _decls2_ be the VarScopedDeclarations of the second |Statement|.
+ 1. Return the list-concatenation of _decls1_ and _decls2_.
IfStatement : `if` `(` Expression `)` Statement
@@ -8035,9 +8573,9 @@ Static Semantics: VarScopedDeclarations ( ): a List of Parse Nodes
ForStatement : `for` `(` `var` VariableDeclarationList `;` Expression? `;` Expression? `)` Statement
- 1. Let _declarations1_ be the VarScopedDeclarations of |VariableDeclarationList|.
- 1. Let _declarations2_ be the VarScopedDeclarations of |Statement|.
- 1. Return the list-concatenation of _declarations1_ and _declarations2_.
+ 1. Let _decls1_ be the VarScopedDeclarations of |VariableDeclarationList|.
+ 1. Let _decls2_ be the VarScopedDeclarations of |Statement|.
+ 1. Return the list-concatenation of _decls1_ and _decls2_.
ForStatement : `for` `(` LexicalDeclaration Expression? `;` Expression? `)` Statement
@@ -8062,9 +8600,9 @@ Static Semantics: VarScopedDeclarations ( ): a List of Parse Nodes
`for` `await` `(` `var` ForBinding `of` AssignmentExpression `)` Statement
- 1. Let _declarations1_ be « |ForBinding| ».
- 1. Let _declarations2_ be the VarScopedDeclarations of |Statement|.
- 1. Return the list-concatenation of _declarations1_ and _declarations2_.
+ 1. Let _decls1_ be « |ForBinding| ».
+ 1. Let _decls2_ be the VarScopedDeclarations of |Statement|.
+ 1. Return the list-concatenation of _decls1_ and _decls2_.
This section is extended by Annex
@@ -8083,18 +8621,18 @@ Static Semantics: VarScopedDeclarations ( ): a List of Parse Nodes
CaseBlock : `{` CaseClauses? DefaultClause CaseClauses? `}`
- 1. If the first |CaseClauses| is present, let _declarations1_ be the VarScopedDeclarations of the first |CaseClauses|.
- 1. Else, let _declarations1_ be a new empty List.
- 1. Let _declarations2_ be the VarScopedDeclarations of |DefaultClause|.
- 1. If the second |CaseClauses| is present, let _declarations3_ be the VarScopedDeclarations of the second |CaseClauses|.
- 1. Else, let _declarations3_ be a new empty List.
- 1. Return the list-concatenation of _declarations1_, _declarations2_, and _declarations3_.
+ 1. If the first |CaseClauses| is present, let _decls1_ be the VarScopedDeclarations of the first |CaseClauses|.
+ 1. Else, let _decls1_ be a new empty List.
+ 1. Let _decls2_ be the VarScopedDeclarations of |DefaultClause|.
+ 1. If the second |CaseClauses| is present, let _decls3_ be the VarScopedDeclarations of the second |CaseClauses|.
+ 1. Else, let _decls3_ be a new empty List.
+ 1. Return the list-concatenation of _decls1_, _decls2_, and _decls3_.
CaseClauses : CaseClauses CaseClause
- 1. Let _declarations1_ be the VarScopedDeclarations of |CaseClauses|.
- 1. Let _declarations2_ be the VarScopedDeclarations of |CaseClause|.
- 1. Return the list-concatenation of _declarations1_ and _declarations2_.
+ 1. Let _decls1_ be the VarScopedDeclarations of |CaseClauses|.
+ 1. Let _decls2_ be the VarScopedDeclarations of |CaseClause|.
+ 1. Return the list-concatenation of _decls1_ and _decls2_.
CaseClause : `case` Expression `:` StatementList?
@@ -8116,22 +8654,22 @@ Static Semantics: VarScopedDeclarations ( ): a List of Parse Nodes
TryStatement : `try` Block Catch
- 1. Let _declarations1_ be the VarScopedDeclarations of |Block|.
- 1. Let _declarations2_ be the VarScopedDeclarations of |Catch|.
- 1. Return the list-concatenation of _declarations1_ and _declarations2_.
+ 1. Let _decls1_ be the VarScopedDeclarations of |Block|.
+ 1. Let _decls2_ be the VarScopedDeclarations of |Catch|.
+ 1. Return the list-concatenation of _decls1_ and _decls2_.
TryStatement : `try` Block Finally
- 1. Let _declarations1_ be the VarScopedDeclarations of |Block|.
- 1. Let _declarations2_ be the VarScopedDeclarations of |Finally|.
- 1. Return the list-concatenation of _declarations1_ and _declarations2_.
+ 1. Let _decls1_ be the VarScopedDeclarations of |Block|.
+ 1. Let _decls2_ be the VarScopedDeclarations of |Finally|.
+ 1. Return the list-concatenation of _decls1_ and _decls2_.
TryStatement : `try` Block Catch Finally
- 1. Let _declarations1_ be the VarScopedDeclarations of |Block|.
- 1. Let _declarations2_ be the VarScopedDeclarations of |Catch|.
- 1. Let _declarations3_ be the VarScopedDeclarations of |Finally|.
- 1. Return the list-concatenation of _declarations1_, _declarations2_, and _declarations3_.
+ 1. Let _decls1_ be the VarScopedDeclarations of |Block|.
+ 1. Let _decls2_ be the VarScopedDeclarations of |Catch|.
+ 1. Let _decls3_ be the VarScopedDeclarations of |Finally|.
+ 1. Return the list-concatenation of _decls1_, _decls2_, and _decls3_.
Catch : `catch` `(` CatchParameter `)` Block
@@ -8177,9 +8715,9 @@ Static Semantics: VarScopedDeclarations ( ): a List of Parse Nodes
ModuleItemList : ModuleItemList ModuleItem
- 1. Let _declarations1_ be the VarScopedDeclarations of |ModuleItemList|.
- 1. Let _declarations2_ be the VarScopedDeclarations of |ModuleItem|.
- 1. Return the list-concatenation of _declarations1_ and _declarations2_.
+ 1. Let _decls1_ be the VarScopedDeclarations of |ModuleItemList|.
+ 1. Let _decls2_ be the VarScopedDeclarations of |ModuleItem|.
+ 1. Return the list-concatenation of _decls1_ and _decls2_.
ModuleItem : ImportDeclaration
@@ -8223,9 +8761,9 @@ Static Semantics: TopLevelLexicallyScopedDeclarations ( ): a List of Parse N
StatementList : StatementList StatementListItem
- 1. Let _declarations1_ be the TopLevelLexicallyScopedDeclarations of |StatementList|.
- 1. Let _declarations2_ be the TopLevelLexicallyScopedDeclarations of |StatementListItem|.
- 1. Return the list-concatenation of _declarations1_ and _declarations2_.
+ 1. Let _decls1_ be the TopLevelLexicallyScopedDeclarations of |StatementList|.
+ 1. Let _decls2_ be the TopLevelLexicallyScopedDeclarations of |StatementListItem|.
+ 1. Return the list-concatenation of _decls1_ and _decls2_.
StatementListItem : Statement
@@ -8284,9 +8822,9 @@ Static Semantics: TopLevelVarScopedDeclarations ( ): a List of Parse Nodes
StatementList : StatementList StatementListItem
- 1. Let _declarations1_ be the TopLevelVarScopedDeclarations of |StatementList|.
- 1. Let _declarations2_ be the TopLevelVarScopedDeclarations of |StatementListItem|.
- 1. Return the list-concatenation of _declarations1_ and _declarations2_.
+ 1. Let _decls1_ be the TopLevelVarScopedDeclarations of |StatementList|.
+ 1. Let _decls2_ be the TopLevelVarScopedDeclarations of |StatementListItem|.
+ 1. Return the list-concatenation of _decls1_ and _decls2_.
StatementListItem : Statement
@@ -8296,8 +8834,8 @@ Static Semantics: TopLevelVarScopedDeclarations ( ): a List of Parse NodesStatementListItem : Declaration
1. If |Declaration| is Declaration : HoistableDeclaration , then
- 1. Let _declaration_ be the DeclarationPart of |HoistableDeclaration|.
- 1. Return « _declaration_ ».
+ 1. Let _decl_ be the DeclarationPart of |HoistableDeclaration|.
+ 1. Return « _decl_ ».
1. Return a new empty List.
LabelledStatement : LabelIdentifier `:` LabelledItem
@@ -8575,8 +9113,8 @@
BreakStatement : `break` LabelIdentifier `;`
- 1. If _labelSet_ does not contain the StringValue of |LabelIdentifier|, return *true*.
- 1. Return *false*.
+ 1. If _labelSet_ contains the StringValue of |LabelIdentifier|, return *false*.
+ 1. Return *true*.
WithStatement : `with` `(` Expression `)` Statement
@@ -8764,8 +9302,8 @@
ContinueStatement : `continue` LabelIdentifier `;`
- 1. If _iterationSet_ does not contain the StringValue of |LabelIdentifier|, return *true*.
- 1. Return *false*.
+ 1. If _iterationSet_ contains the StringValue of |LabelIdentifier|, return *false*.
+ 1. Return *true*.
WithStatement : `with` `(` Expression `)` Statement
@@ -8969,7 +9507,7 @@ Static Semantics: IsFunctionDefinition ( ): a Boolean
`-` UnaryExpression
`~` UnaryExpression
`!` UnaryExpression
- AwaitExpression
+ CoverAwaitExpressionAndAwaitUsingDeclarationHead
ExponentiationExpression :
UpdateExpression `**` ExponentiationExpression
@@ -9175,9 +9713,8 @@
ClassExpression : `class` ClassTail
- 1. Let _value_ be ? ClassDefinitionEvaluation of |ClassTail| with arguments *undefined* and _name_.
- 1. Set _value_.[[SourceText]] to the source text matched by |ClassExpression|.
- 1. Return _value_.
+ 1. Let _sourceText_ be the source text matched by |ClassExpression|.
+ 1. Return ? ClassDefinitionEvaluation of |ClassTail| with arguments *undefined*, _name_, and _sourceText_.
@@ -9241,7 +9778,8 @@
1. If _symbol_ is |ClassBody|, return *true*.
1. If _symbol_ is |ClassHeritage|, then
- 1. If |ClassHeritage| is present, return *true*; otherwise return *false*.
+ 1. If |ClassHeritage| is present, return *true*.
+ 1. Return *false*.
1. If |ClassHeritage| is present, then
1. If |ClassHeritage| Contains _symbol_ is *true*, return *true*.
1. Return the result of ComputedPropertyContains of |ClassBody| with argument _symbol_.
@@ -9394,7 +9932,7 @@ Miscellaneous
Runtime Semantics: InstantiateFunctionObject (
- _env_: an Environment Record,
+ _envRecord_: an Environment Record,
_privateEnv_: a PrivateEnvironment Record or *null*,
): an ECMAScript function object
@@ -9406,7 +9944,7 @@
`function` `(` FormalParameters `)` `{` FunctionBody `}`
- 1. Return InstantiateOrdinaryFunctionObject of |FunctionDeclaration| with arguments _env_ and _privateEnv_.
+ 1. Return InstantiateOrdinaryFunctionObject of |FunctionDeclaration| with arguments _envRecord_ and _privateEnv_.
GeneratorDeclaration :
@@ -9414,7 +9952,7 @@
`function` `*` `(` FormalParameters `)` `{` GeneratorBody `}`
- 1. Return InstantiateGeneratorFunctionObject of |GeneratorDeclaration| with arguments _env_ and _privateEnv_.
+ 1. Return InstantiateGeneratorFunctionObject of |GeneratorDeclaration| with arguments _envRecord_ and _privateEnv_.
AsyncGeneratorDeclaration :
@@ -9422,7 +9960,7 @@
`async` `function` `*` `(` FormalParameters `)` `{` AsyncGeneratorBody `}`
- 1. Return InstantiateAsyncGeneratorFunctionObject of |AsyncGeneratorDeclaration| with arguments _env_ and _privateEnv_.
+ 1. Return InstantiateAsyncGeneratorFunctionObject of |AsyncGeneratorDeclaration| with arguments _envRecord_ and _privateEnv_.
AsyncFunctionDeclaration :
@@ -9430,7 +9968,7 @@
`async` `function` `(` FormalParameters `)` `{` AsyncFunctionBody `}`
- 1. Return InstantiateAsyncFunctionObject of |AsyncFunctionDeclaration| with arguments _env_ and _privateEnv_.
+ 1. Return InstantiateAsyncFunctionObject of |AsyncFunctionDeclaration| with arguments _envRecord_ and _privateEnv_.
@@ -9438,36 +9976,36 @@
Runtime Semantics: BindingInitialization (
_value_: an ECMAScript language value,
- _environment_: an Environment Record or *undefined*,
+ _envRecord_: an Environment Record or *undefined*,
): either a normal completion containing ~unused~ or an abrupt completion
- *undefined* is passed for _environment_ to indicate that a PutValue operation should be used to assign the initialization value. This is the case for `var` statements and formal parameter lists of some non-strict functions (See
+ *undefined* is passed for _envRecord_ to indicate that a PutValue operation should be used to assign the initialization value. This is the case for `var` statements and formal parameter lists of some non-strict functions (See
BindingIdentifier : Identifier
1. Let _name_ be the StringValue of |Identifier|.
- 1. Return ? InitializeBoundName(_name_, _value_, _environment_).
+ 1. Return ? InitializeBoundName(_name_, _value_, _envRecord_).
BindingIdentifier : `yield`
- 1. Return ? InitializeBoundName(*"yield"*, _value_, _environment_).
+ 1. Return ? InitializeBoundName(*"yield"*, _value_, _envRecord_).
BindingIdentifier : `await`
- 1. Return ? InitializeBoundName(*"await"*, _value_, _environment_).
+ 1. Return ? InitializeBoundName(*"await"*, _value_, _envRecord_).
BindingPattern : ObjectBindingPattern
1. Perform ? RequireObjectCoercible(_value_).
- 1. Return ? BindingInitialization of |ObjectBindingPattern| with arguments _value_ and _environment_.
+ 1. Return ? BindingInitialization of |ObjectBindingPattern| with arguments _value_ and _envRecord_.
BindingPattern : ArrayBindingPattern
1. Let _iteratorRecord_ be ? GetIterator(_value_, ~sync~).
- 1. Let _result_ be Completion(IteratorBindingInitialization of |ArrayBindingPattern| with arguments _iteratorRecord_ and _environment_).
+ 1. Let _result_ be Completion(IteratorBindingInitialization of |ArrayBindingPattern| with arguments _iteratorRecord_ and _envRecord_).
1. If _iteratorRecord_.[[Done]] is *false*, return ? IteratorClose(_iteratorRecord_, _result_).
1. Return ? _result_.
@@ -9481,18 +10019,18 @@
`{` BindingPropertyList `,` `}`
- 1. Perform ? PropertyBindingInitialization of |BindingPropertyList| with arguments _value_ and _environment_.
+ 1. Perform ? PropertyBindingInitialization of |BindingPropertyList| with arguments _value_ and _envRecord_.
1. Return ~unused~.
ObjectBindingPattern : `{` BindingRestProperty `}`
1. Let _excludedNames_ be a new empty List.
- 1. Return ? RestBindingInitialization of |BindingRestProperty| with arguments _value_, _environment_, and _excludedNames_.
+ 1. Return ? RestBindingInitialization of |BindingRestProperty| with arguments _value_, _envRecord_, and _excludedNames_.
ObjectBindingPattern : `{` BindingPropertyList `,` BindingRestProperty `}`
- 1. Let _excludedNames_ be ? PropertyBindingInitialization of |BindingPropertyList| with arguments _value_ and _environment_.
- 1. Return ? RestBindingInitialization of |BindingRestProperty| with arguments _value_, _environment_, and _excludedNames_.
+ 1. Let _excludedNames_ be ? PropertyBindingInitialization of |BindingPropertyList| with arguments _value_ and _envRecord_.
+ 1. Return ? RestBindingInitialization of |BindingRestProperty| with arguments _value_, _envRecord_, and _excludedNames_.
@@ -9500,18 +10038,17 @@
InitializeBoundName (
_name_: a String,
_value_: an ECMAScript language value,
- _environment_: an Environment Record or *undefined*,
+ _envRecord_: an Environment Record or *undefined*,
): either a normal completion containing ~unused~ or an abrupt completion
- 1. If _environment_ is not *undefined*, then
- 1. Perform ! _environment_.InitializeBinding(_name_, _value_).
+ 1. If _envRecord_ is not *undefined*, then
+ 1. Perform ! _envRecord_.InitializeBinding(_name_, _value_).
1. Return ~unused~.
- 1. Else,
- 1. Let _lhs_ be ? ResolveBinding(_name_).
- 1. Return ? PutValue(_lhs_, _value_).
+ 1. Let _lhs_ be ? ResolveBinding(_name_).
+ 1. Return ? PutValue(_lhs_, _value_).
@@ -9520,13 +10057,13 @@
Runtime Semantics: IteratorBindingInitialization (
_iteratorRecord_: an Iterator Record,
- _environment_: an Environment Record or *undefined*,
+ _envRecord_: an Environment Record or *undefined*,
): either a normal completion containing ~unused~ or an abrupt completion
- When *undefined* is passed for _environment_ it indicates that a PutValue operation should be used to assign the initialization value. This is the case for formal parameter lists of non-strict functions. In that case the formal parameter bindings are preinitialized in order to deal with the possibility of multiple parameters with the same name.
+ When *undefined* is passed for _envRecord_ it indicates that a PutValue operation should be used to assign the initialization value. This is the case for formal parameter lists of non-strict functions. In that case the formal parameter bindings are preinitialized in order to deal with the possibility of multiple parameters with the same name.
ArrayBindingPattern : `[` `]`
@@ -9540,34 +10077,34 @@
1. If |Elision| is present, then
1. Perform ? IteratorDestructuringAssignmentEvaluation of |Elision| with argument _iteratorRecord_.
- 1. Return ? IteratorBindingInitialization of |BindingRestElement| with arguments _iteratorRecord_ and _environment_.
+ 1. Return ? IteratorBindingInitialization of |BindingRestElement| with arguments _iteratorRecord_ and _envRecord_.
ArrayBindingPattern : `[` BindingElementList `,` Elision `]`
- 1. Perform ? IteratorBindingInitialization of |BindingElementList| with arguments _iteratorRecord_ and _environment_.
+ 1. Perform ? IteratorBindingInitialization of |BindingElementList| with arguments _iteratorRecord_ and _envRecord_.
1. Return ? IteratorDestructuringAssignmentEvaluation of |Elision| with argument _iteratorRecord_.
ArrayBindingPattern : `[` BindingElementList `,` Elision? BindingRestElement `]`
- 1. Perform ? IteratorBindingInitialization of |BindingElementList| with arguments _iteratorRecord_ and _environment_.
+ 1. Perform ? IteratorBindingInitialization of |BindingElementList| with arguments _iteratorRecord_ and _envRecord_.
1. If |Elision| is present, then
1. Perform ? IteratorDestructuringAssignmentEvaluation of |Elision| with argument _iteratorRecord_.
- 1. Return ? IteratorBindingInitialization of |BindingRestElement| with arguments _iteratorRecord_ and _environment_.
+ 1. Return ? IteratorBindingInitialization of |BindingRestElement| with arguments _iteratorRecord_ and _envRecord_.
BindingElementList : BindingElementList `,` BindingElisionElement
- 1. Perform ? IteratorBindingInitialization of |BindingElementList| with arguments _iteratorRecord_ and _environment_.
- 1. Return ? IteratorBindingInitialization of |BindingElisionElement| with arguments _iteratorRecord_ and _environment_.
+ 1. Perform ? IteratorBindingInitialization of |BindingElementList| with arguments _iteratorRecord_ and _envRecord_.
+ 1. Return ? IteratorBindingInitialization of |BindingElisionElement| with arguments _iteratorRecord_ and _envRecord_.
BindingElisionElement : Elision BindingElement
1. Perform ? IteratorDestructuringAssignmentEvaluation of |Elision| with argument _iteratorRecord_.
- 1. Return ? IteratorBindingInitialization of |BindingElement| with arguments _iteratorRecord_ and _environment_.
+ 1. Return ? IteratorBindingInitialization of |BindingElement| with arguments _iteratorRecord_ and _envRecord_.
SingleNameBinding : BindingIdentifier Initializer?
1. Let _bindingId_ be the StringValue of |BindingIdentifier|.
- 1. Let _lhs_ be ? ResolveBinding(_bindingId_, _environment_).
+ 1. Let _lhs_ be ? ResolveBinding(_bindingId_, _envRecord_).
1. Let _v_ be *undefined*.
1. If _iteratorRecord_.[[Done]] is *false*, then
1. Let _next_ be ? IteratorStepValue(_iteratorRecord_).
@@ -9579,7 +10116,7 @@
1. Else,
1. Let _defaultValue_ be ? Evaluation of |Initializer|.
1. Set _v_ to ? GetValue(_defaultValue_).
- 1. If _environment_ is *undefined*, return ? PutValue(_lhs_, _v_).
+ 1. If _envRecord_ is *undefined*, return ? PutValue(_lhs_, _v_).
1. Return ? InitializeReferencedBinding(_lhs_, _v_).
BindingElement : BindingPattern Initializer?
@@ -9592,34 +10129,34 @@
1. If |Initializer| is present and _v_ is *undefined*, then
1. Let _defaultValue_ be ? Evaluation of |Initializer|.
1. Set _v_ to ? GetValue(_defaultValue_).
- 1. Return ? BindingInitialization of |BindingPattern| with arguments _v_ and _environment_.
+ 1. Return ? BindingInitialization of |BindingPattern| with arguments _v_ and _envRecord_.
BindingRestElement : `...` BindingIdentifier
- 1. Let _lhs_ be ? ResolveBinding(StringValue of |BindingIdentifier|, _environment_).
- 1. Let _A_ be ! ArrayCreate(0).
+ 1. Let _lhs_ be ? ResolveBinding(StringValue of |BindingIdentifier|, _envRecord_).
+ 1. Let _array_ be ! ArrayCreate(0).
1. Let _n_ be 0.
1. Repeat,
1. Let _next_ be ~done~.
1. If _iteratorRecord_.[[Done]] is *false*, then
1. Set _next_ to ? IteratorStepValue(_iteratorRecord_).
1. If _next_ is ~done~, then
- 1. If _environment_ is *undefined*, return ? PutValue(_lhs_, _A_).
- 1. Return ? InitializeReferencedBinding(_lhs_, _A_).
- 1. Perform ! CreateDataPropertyOrThrow(_A_, ! ToString(𝔽(_n_)), _next_).
+ 1. If _envRecord_ is *undefined*, return ? PutValue(_lhs_, _array_).
+ 1. Return ? InitializeReferencedBinding(_lhs_, _array_).
+ 1. Perform ! CreateDataPropertyOrThrow(_array_, ! ToString(𝔽(_n_)), _next_).
1. Set _n_ to _n_ + 1.
BindingRestElement : `...` BindingPattern
- 1. Let _A_ be ! ArrayCreate(0).
+ 1. Let _array_ be ! ArrayCreate(0).
1. Let _n_ be 0.
1. Repeat,
1. Let _next_ be ~done~.
1. If _iteratorRecord_.[[Done]] is *false*, then
1. Set _next_ to ? IteratorStepValue(_iteratorRecord_).
1. If _next_ is ~done~, then
- 1. Return ? BindingInitialization of |BindingPattern| with arguments _A_ and _environment_.
- 1. Perform ! CreateDataPropertyOrThrow(_A_, ! ToString(𝔽(_n_)), _next_).
+ 1. Return ? BindingInitialization of |BindingPattern| with arguments _array_ and _envRecord_.
+ 1. Perform ! CreateDataPropertyOrThrow(_array_, ! ToString(𝔽(_n_)), _next_).
1. Set _n_ to _n_ + 1.
FormalParameters : [empty]
@@ -9628,13 +10165,13 @@
FormalParameters : FormalParameterList `,` FunctionRestParameter
- 1. Perform ? IteratorBindingInitialization of |FormalParameterList| with arguments _iteratorRecord_ and _environment_.
- 1. Return ? IteratorBindingInitialization of |FunctionRestParameter| with arguments _iteratorRecord_ and _environment_.
+ 1. Perform ? IteratorBindingInitialization of |FormalParameterList| with arguments _iteratorRecord_ and _envRecord_.
+ 1. Return ? IteratorBindingInitialization of |FunctionRestParameter| with arguments _iteratorRecord_ and _envRecord_.
FormalParameterList : FormalParameterList `,` FormalParameter
- 1. Perform ? IteratorBindingInitialization of |FormalParameterList| with arguments _iteratorRecord_ and _environment_.
- 1. Return ? IteratorBindingInitialization of |FormalParameter| with arguments _iteratorRecord_ and _environment_.
+ 1. Perform ? IteratorBindingInitialization of |FormalParameterList| with arguments _iteratorRecord_ and _envRecord_.
+ 1. Return ? IteratorBindingInitialization of |FormalParameter| with arguments _iteratorRecord_ and _envRecord_.
ArrowParameters : BindingIdentifier
@@ -9643,12 +10180,12 @@
1. Let _next_ be ? IteratorStepValue(_iteratorRecord_).
1. If _next_ is not ~done~, then
1. Set _v_ to _next_.
- 1. Return ? BindingInitialization of |BindingIdentifier| with arguments _v_ and _environment_.
+ 1. Return ? BindingInitialization of |BindingIdentifier| with arguments _v_ and _envRecord_.
ArrowParameters : CoverParenthesizedExpressionAndArrowParameterList
1. Let _formals_ be the |ArrowFormalParameters| that is covered by |CoverParenthesizedExpressionAndArrowParameterList|.
- 1. Return ? IteratorBindingInitialization of _formals_ with arguments _iteratorRecord_ and _environment_.
+ 1. Return ? IteratorBindingInitialization of _formals_ with arguments _iteratorRecord_ and _envRecord_.
AsyncArrowBindingIdentifier : BindingIdentifier
@@ -9659,12 +10196,12 @@
1. Let _next_ be ? IteratorStepValue(_iteratorRecord_).
1. If _next_ is not ~done~, then
1. Set _v_ to _next_.
- 1. Return ? BindingInitialization of |BindingIdentifier| with arguments _v_ and _environment_.
+ 1. Return ? BindingInitialization of |BindingIdentifier| with arguments _v_ and _envRecord_.
- Static Semantics: AssignmentTargetType ( ): ~simple~ or ~invalid~
+ Static Semantics: AssignmentTargetType ( ): ~simple~, ~web-compat~, or ~invalid~
IdentifierReference : Identifier
@@ -9699,6 +10236,16 @@ Static Semantics: AssignmentTargetType ( ): ~simple~ or ~invalid~
1. Let _expr_ be the |ParenthesizedExpression| that is covered by |CoverParenthesizedExpressionAndArrowParameterList|.
1. Return the AssignmentTargetType of _expr_.
+
+ CallExpression :
+ CoverCallExpressionAndAsyncArrowHead
+ CallExpression Arguments
+
+
+ 1. [id="step-assignmenttargettype-web-compat", normative-optional] If the host is a web browser or otherwise supports
PrimaryExpression :
`this`
@@ -9714,10 +10261,8 @@ Static Semantics: AssignmentTargetType ( ): ~simple~ or ~invalid~
TemplateLiteral
CallExpression :
- CoverCallExpressionAndAsyncArrowHead
SuperCall
ImportCall
- CallExpression Arguments
CallExpression TemplateLiteral
NewExpression :
@@ -9750,7 +10295,7 @@ Static Semantics: AssignmentTargetType ( ): ~simple~ or ~invalid~
`-` UnaryExpression
`~` UnaryExpression
`!` UnaryExpression
- AwaitExpression
+ CoverAwaitExpressionAndAwaitUsingDeclarationHead
ExponentiationExpression :
UpdateExpression `**` ExponentiationExpression
@@ -9837,18 +10382,26 @@ Static Semantics: PropName ( ): a String or ~empty~
1. Return the PropName of |PropertyName|.
- LiteralPropertyName : IdentifierName
+
+ LiteralPropertyName : IdentifierName
+
+ AttributeKey : IdentifierName
+
1. Return the StringValue of |IdentifierName|.
- LiteralPropertyName : StringLiteral
+
+ LiteralPropertyName : StringLiteral
+
+ AttributeKey : StringLiteral
+
1. Return the SV of |StringLiteral|.
LiteralPropertyName : NumericLiteral
- 1. Let _nbr_ be the NumericValue of |NumericLiteral|.
- 1. Return ! ToString(_nbr_).
+ 1. Let _number_ be the NumericValue of |NumericLiteral|.
+ 1. Return ! ToString(_number_).
ComputedPropertyName : `[` AssignmentExpression `]`
@@ -9898,6 +10451,28 @@ Static Semantics: PropName ( ): a String or ~empty~
1. Return ~empty~.
+
+
+ Static Semantics: ContainsUsing ( ): a Boolean
+
+
+ StatementList : StatementList StatementListItem
+
+ 1. If ContainsUsing of the derived |StatementList| is *true*, return *true*.
+ 1. If ContainsUsing of |StatementListItem| is *true*, return *true*.
+ 1. Return *false*.
+
+ StatementListItem : Statement
+
+ 1. Return *false*.
+
+ StatementListItem : Declaration
+
+ 1. If IsUsingDeclaration of |Declaration| is *true*, return *true*.
+ 1. If IsAwaitUsingDeclaration of |Declaration| is *true*, return *true*.
+ 1. Return *false*.
+
+
@@ -9907,7 +10482,7 @@ Executable Code and Execution Contexts
Environment Records
Environment Record is a specification type used to define the association of |Identifier|s to specific variables and functions, based upon the lexical nesting structure of ECMAScript code. Usually an Environment Record is associated with some specific syntactic structure of ECMAScript code such as a |FunctionDeclaration|, a |BlockStatement|, or a |Catch| clause of a |TryStatement|. Each time such code is evaluated, a new Environment Record is created to record the identifier bindings that are created by that code.
- Every Environment Record has an [[OuterEnv]] field, which is either *null* or a reference to an outer Environment Record. This is used to model the logical nesting of Environment Record values. The outer reference of an (inner) Environment Record is a reference to the Environment Record that logically surrounds the inner Environment Record. An outer Environment Record may, of course, have its own outer Environment Record. An Environment Record may serve as the outer environment for multiple inner Environment Records. For example, if a |FunctionDeclaration| contains two nested |FunctionDeclaration|s then the Environment Records of each of the nested functions will have as their outer Environment Record the Environment Record of the current evaluation of the surrounding function.
+ Every Environment Record has an [[OuterEnv]] field, which is either *null* or a reference to an outer Environment Record. This is used to model the logical nesting of Environment Records. The outer reference of an (inner) Environment Record is a reference to the Environment Record that logically surrounds the inner Environment Record. An outer Environment Record may, of course, have its own outer Environment Record. An Environment Record may serve as the outer environment for multiple inner Environment Records. For example, if a |FunctionDeclaration| contains two nested |FunctionDeclaration|s then the Environment Records of each of the nested functions will have as their outer Environment Record the Environment Record of the current evaluation of the surrounding function.
Environment Records are purely specification mechanisms and need not correspond to any specific artefact of an ECMAScript implementation. It is impossible for an ECMAScript program to directly access or manipulate such values.
@@ -9939,94 +10514,163 @@ The Environment Record Type Hierarchy
The Environment Record abstract class includes the abstract specification methods defined in
-
+
-
-
- Method
-
-
- Purpose
-
+
+
+
+ Method
+
+
+ Purpose
+
+
+ Definitions
+
+
+
+
+
+ HasBinding (
+ _name_: a String,
+ ): either a normal completion containing a Boolean or a throw completion
+
+
+ It determines if an Environment Record has a binding for _name_.
+
+
+ It has concrete definitions in the following types:
+
-
+
+
+ CreateMutableBinding (
+ _name_: a String,
+ _deletable_: a Boolean,
+ ): either a normal completion containing ~unused~ or a throw completion
+
- HasBinding(N)
+ It creates a new but uninitialized mutable binding in an Environment Record. _name_ is the text of the bound name. If _deletable_ is *true* the binding may be subsequently deleted.
- Determine if an Environment Record has a binding for the String value _N_. Return *true* if it does and *false* if it does not.
+ It has concrete definitions in the following types:
+
-
+
- CreateMutableBinding(N, D)
+ CreateImmutableBinding (
+ _name_: a String,
+ _strict_: a Boolean,
+ ): either a normal completion containing ~unused~ or a throw completion
- Create a new but uninitialized mutable binding in an Environment Record. The String value _N_ is the text of the bound name. If the Boolean argument _D_ is *true* the binding may be subsequently deleted.
+ It creates a new but uninitialized immutable binding in an Environment Record. _name_ is the text of the bound name. If _strict_ is *true* then attempts to set it after it has been initialized will always throw an exception, regardless of the strict mode setting of operations that reference that binding.
+
+
+ It has concrete definitions in the following types:
+
-
+
- CreateImmutableBinding(N, S)
+ InitializeBinding (
+ _name_: a String,
+ _value_: an ECMAScript language value,
+ ): either a normal completion containing ~unused~ or a throw completion
- Create a new but uninitialized immutable binding in an Environment Record. The String value _N_ is the text of the bound name. If _S_ is *true* then attempts to set it after it has been initialized will always throw an exception, regardless of the strict mode setting of operations that reference that binding.
+ It sets the value of an already existing but uninitialized binding in an Environment Record. _name_ is the text of the bound name. _value_ is the value for the binding.
+
+
+ It has concrete definitions in the following types:
+
-
+
+
+ SetMutableBinding (
+ _name_: a String,
+ _value_: an ECMAScript language value,
+ _strict_: a Boolean,
+ ): either a normal completion containing ~unused~ or a throw completion
+
- InitializeBinding(N, V)
+ It sets the value of an already existing mutable binding in an Environment Record. _name_ is the text of the bound name. _value_ is the value for the binding. If _strict_ is *true* and the binding cannot be set, this will throw a *TypeError* exception.
- Set the value of an already existing but uninitialized binding in an Environment Record. The String value _N_ is the text of the bound name. _V_ is the value for the binding and is a value of any ECMAScript language type.
+ It has concrete definitions in the following types:
+
-
+
+
+ GetBindingValue (
+ _name_: a String,
+ _strict_: a Boolean,
+ ): either a normal completion containing an ECMAScript language value or a throw completion
+
- SetMutableBinding(N, V, S)
+ It returns the value of an already existing binding from an Environment Record. _name_ is the text of the bound name. _strict_ is used to identify references originating in strict mode code or that otherwise require strict mode reference semantics. If _strict_ is *true* and the binding does not exist, this will throw a *ReferenceError* exception. If the binding exists but is uninitialized a *ReferenceError* is thrown, regardless of the value of _strict_.
- Set the value of an already existing mutable binding in an Environment Record. The String value _N_ is the text of the bound name. _V_ is the value for the binding and may be a value of any ECMAScript language type. _S_ is a Boolean flag. If _S_ is *true* and the binding cannot be set throw a *TypeError* exception.
+ It has concrete definitions in the following types:
+
-
+
- GetBindingValue(N, S)
+ DeleteBinding (
+ _name_: a String,
+ ): either a normal completion containing a Boolean or a throw completion
- Returns the value of an already existing binding from an Environment Record. The String value _N_ is the text of the bound name. _S_ is used to identify references originating in strict mode code or that otherwise require strict mode reference semantics. If _S_ is *true* and the binding does not exist throw a *ReferenceError* exception. If the binding exists but is uninitialized a *ReferenceError* is thrown, regardless of the value of _S_.
+ It deletes a binding from an Environment Record. _name_ is the text of the bound name. If a binding for _name_ exists, this removes the binding and returns *true*. If the binding exists but cannot be removed, this returns *false*. If the binding does not exist, this returns *true*.
+
+
+ It has concrete definitions in the following types:
+
-
+
+ HasThisBinding ( ): a Boolean
- DeleteBinding(N)
+ It determines if an Environment Record establishes a `this` binding. This returns *true* if it does and *false* if it does not.
- Delete a binding from an Environment Record. The String value _N_ is the text of the bound name. If a binding for _N_ exists, remove the binding and return *true*. If the binding exists but cannot be removed return *false*. If the binding does not exist return *true*.
+ It has concrete definitions in the following types:
+
-
+
+ GetThisBinding ( ): either a normal completion containing an ECMAScript language value or a throw completion
- HasThisBinding()
+ It returns the value of this Environment Record's `this` binding. It throws a *ReferenceError* if the `this` binding has not been initialized.
- Determine if an Environment Record establishes a `this` binding. Return *true* if it does and *false* if it does not.
+ It has concrete definitions in the following types:
+
-
+
+ HasSuperBinding ( ): a Boolean
- HasSuperBinding()
+ It determines if an Environment Record establishes a `super` method binding. This returns *true* if it does and *false* if it does not. If it returns *true* it implies that the Environment Record is a Function Environment Record, although the reverse implication does not hold.
- Determine if an Environment Record establishes a `super` method binding. Return *true* if it does and *false* if it does not.
+ It has concrete definitions in the following types:
+
-
+
+ WithBaseObject ( ): an Object or *undefined*
- WithBaseObject()
+ If this Environment Record is associated with a `with` statement, it returns the with object. Otherwise, it returns *undefined*.
- If this Environment Record is associated with a `with` statement, return the with object. Otherwise, return *undefined*.
+ It has concrete definitions in the following types:
+
@@ -10035,23 +10679,23 @@ The Environment Record Type Hierarchy
Declarative Environment Records
Each Declarative Environment Record is associated with an ECMAScript program scope containing variable, constant, let, class, module, import, and/or function declarations. A Declarative Environment Record binds the set of identifiers defined by the declarations contained within its scope.
- The behaviour of the concrete specification methods for Declarative Environment Records is defined by the following algorithms.
+ Every Declarative Environment Record also has a [[DisposableResourceStack]] field, which contains a List of DisposableResource Records. The elements of this list are tracked by the `using` declarations and `await using` declarations that must be disposed when the Evaluation step that constructed the Environment Record has completed.
HasBinding (
- _N_: a String,
+ _name_: a String,
): a normal completion containing a Boolean
- for
- - a Declarative Environment Record _envRec_
+ - a Declarative Environment Record _envRecord_
- description
- It determines if the argument identifier is one of the identifiers bound by the record.
- 1. If _envRec_ has a binding for _N_, return *true*.
+ 1. If _envRecord_ has a binding for _name_, return *true*.
1. Return *false*.
@@ -10059,20 +10703,20 @@
CreateMutableBinding (
- _N_: a String,
- _D_: a Boolean,
+ _name_: a String,
+ _deletable_: a Boolean,
): a normal completion containing ~unused~
- for
- - a Declarative Environment Record _envRec_
+ - a Declarative Environment Record _envRecord_
- description
- - It creates a new mutable binding for the name _N_ that is uninitialized. A binding must not already exist in this Environment Record for _N_. If _D_ is *true*, the new binding is marked as being subject to deletion.
+ - It creates a new mutable binding for the name _name_ that is uninitialized. A binding must not already exist in this Environment Record for _name_. If _deletable_ is *true*, the new binding is marked as being subject to deletion.
- 1. Assert: _envRec_ does not already have a binding for _N_.
- 1. Create a mutable binding in _envRec_ for _N_ and record that it is uninitialized. If _D_ is *true*, record that the newly created binding may be deleted by a subsequent DeleteBinding call.
+ 1. Assert: _envRecord_ does not already have a binding for _name_.
+ 1. Create a mutable binding in _envRecord_ for _name_ and record that it is uninitialized. If _deletable_ is *true*, record that the newly created binding may be deleted by a subsequent DeleteBinding call.
1. Return ~unused~.
@@ -10080,20 +10724,20 @@
CreateImmutableBinding (
- _N_: a String,
- _S_: a Boolean,
+ _name_: a String,
+ _strict_: a Boolean,
): a normal completion containing ~unused~
- for
- - a Declarative Environment Record _envRec_
+ - a Declarative Environment Record _envRecord_
- description
- - It creates a new immutable binding for the name _N_ that is uninitialized. A binding must not already exist in this Environment Record for _N_. If _S_ is *true*, the new binding is marked as a strict binding.
+ - It creates a new immutable binding for the name _name_ that is uninitialized. A binding must not already exist in this Environment Record for _name_. If _strict_ is *true*, the new binding is marked as a strict binding.
- 1. Assert: _envRec_ does not already have a binding for _N_.
- 1. Create an immutable binding in _envRec_ for _N_ and record that it is uninitialized. If _S_ is *true*, record that the newly created binding is a strict binding.
+ 1. Assert: _envRecord_ does not already have a binding for _name_.
+ 1. Create an immutable binding in _envRecord_ for _name_ and record that it is uninitialized. If _strict_ is *true*, record that the newly created binding is a strict binding.
1. Return ~unused~.
@@ -10101,21 +10745,21 @@
InitializeBinding (
- _N_: a String,
- _V_: an ECMAScript language value,
+ _name_: a String,
+ _value_: an ECMAScript language value,
): a normal completion containing ~unused~
- for
- - a Declarative Environment Record _envRec_
+ - a Declarative Environment Record _envRecord_
- description
- - It is used to set the bound value of the current binding of the identifier whose name is _N_ to the value _V_. An uninitialized binding for _N_ must already exist.
+ - It is used to set the bound value of the current binding of the identifier whose name is _name_ to the value _value_. An uninitialized binding for _name_ must already exist.
- 1. Assert: _envRec_ must have an uninitialized binding for _N_.
- 1. Set the bound value for _N_ in _envRec_ to _V_.
- 1. Record that the binding for _N_ in _envRec_ has been initialized.
+ 1. Assert: _envRecord_ must have an uninitialized binding for _name_.
+ 1. Set the bound value for _name_ in _envRecord_ to _value_.
+ 1. Record that the binding for _name_ in _envRecord_ has been initialized.
1. Return ~unused~.
@@ -10123,32 +10767,32 @@
SetMutableBinding (
- _N_: a String,
- _V_: an ECMAScript language value,
- _S_: a Boolean,
+ _name_: a String,
+ _value_: an ECMAScript language value,
+ _strict_: a Boolean,
): either a normal completion containing ~unused~ or a throw completion
- for
- - a Declarative Environment Record _envRec_
+ - a Declarative Environment Record _envRecord_
- description
- - It attempts to change the bound value of the current binding of the identifier whose name is _N_ to the value _V_. A binding for _N_ normally already exists, but in rare cases it may not. If the binding is an immutable binding, a *TypeError* is thrown if _S_ is *true*.
+ - It attempts to change the bound value of the current binding of the identifier whose name is _name_ to the value _value_. A binding for _name_ normally already exists, but in rare cases it may not. If the binding is an immutable binding, a *TypeError* is thrown if _strict_ is *true*.
- 1. [id="step-setmutablebinding-missing-binding"] If _envRec_ does not have a binding for _N_, then
- 1. If _S_ is *true*, throw a *ReferenceError* exception.
- 1. Perform ! _envRec_.CreateMutableBinding(_N_, *true*).
- 1. Perform ! _envRec_.InitializeBinding(_N_, _V_).
+ 1. [id="step-setmutablebinding-missing-binding"] If _envRecord_ does not have a binding for _name_, then
+ 1. If _strict_ is *true*, throw a *ReferenceError* exception.
+ 1. Perform ! _envRecord_.CreateMutableBinding(_name_, *true*).
+ 1. Perform ! _envRecord_.InitializeBinding(_name_, _value_).
1. Return ~unused~.
- 1. If the binding for _N_ in _envRec_ is a strict binding, set _S_ to *true*.
- 1. If the binding for _N_ in _envRec_ has not yet been initialized, then
+ 1. If the binding for _name_ in _envRecord_ is a strict binding, set _strict_ to *true*.
+ 1. If the binding for _name_ in _envRecord_ has not yet been initialized, then
1. Throw a *ReferenceError* exception.
- 1. Else if the binding for _N_ in _envRec_ is a mutable binding, then
- 1. Change its bound value to _V_.
+ 1. Else if the binding for _name_ in _envRecord_ is a mutable binding, then
+ 1. Change its bound value to _value_.
1. Else,
1. Assert: This is an attempt to change the value of an immutable binding.
- 1. If _S_ is *true*, throw a *TypeError* exception.
+ 1. If _strict_ is *true*, throw a *TypeError* exception.
1. Return ~unused~.
@@ -10160,41 +10804,41 @@
GetBindingValue (
- _N_: a String,
- _S_: a Boolean,
+ _name_: a String,
+ _strict_: a Boolean,
): either a normal completion containing an ECMAScript language value or a throw completion
- for
- - a Declarative Environment Record _envRec_
+ - a Declarative Environment Record _envRecord_
- description
- - It returns the value of its bound identifier whose name is _N_. If the binding exists but is uninitialized a *ReferenceError* is thrown, regardless of the value of _S_.
+ - It returns the value of its bound identifier whose name is _name_. If the binding exists but is uninitialized a *ReferenceError* is thrown, regardless of the value of _strict_.
- 1. Assert: _envRec_ has a binding for _N_.
- 1. If the binding for _N_ in _envRec_ is an uninitialized binding, throw a *ReferenceError* exception.
- 1. Return the value currently bound to _N_ in _envRec_.
+ 1. Assert: _envRecord_ has a binding for _name_.
+ 1. If the binding for _name_ in _envRecord_ is an uninitialized binding, throw a *ReferenceError* exception.
+ 1. Return the value currently bound to _name_ in _envRecord_.
DeleteBinding (
- _N_: a String,
+ _name_: a String,
): a normal completion containing a Boolean
- for
- - a Declarative Environment Record _envRec_
+ - a Declarative Environment Record _envRecord_
- description
- It can only delete bindings that have been explicitly designated as being subject to deletion.
- 1. Assert: _envRec_ has a binding for _N_.
- 1. If the binding for _N_ in _envRec_ cannot be deleted, return *false*.
- 1. Remove the binding for _N_ from _envRec_.
+ 1. Assert: _envRecord_ has a binding for _name_.
+ 1. If the binding for _name_ in _envRecord_ cannot be deleted, return *false*.
+ 1. Remove the binding for _name_ from _envRecord_.
1. Return *true*.
@@ -10203,7 +10847,7 @@
HasThisBinding ( ): *false*
- for
- - a Declarative Environment Record _envRec_
+ - a Declarative Environment Record _envRecord_
1. Return *false*.
@@ -10213,11 +10857,16 @@ HasThisBinding ( ): *false*
+
+ GetThisBinding ( )
+ The GetThisBinding concrete method of a Declarative Environment Record is never used within this specification.
+
+
HasSuperBinding ( ): *false*
- for
- - a Declarative Environment Record _envRec_
+ - a Declarative Environment Record _envRecord_
1. Return *false*.
@@ -10231,7 +10880,7 @@ HasSuperBinding ( ): *false*
WithBaseObject ( ): *undefined*
- for
- - a Declarative Environment Record _envRec_
+ - a Declarative Environment Record _envRecord_
1. Return *undefined*.
@@ -10246,17 +10895,19 @@ Object Environment Records
Object Environment Records have the additional state fields listed in
-
-
- Field Name
-
-
- Value
-
-
- Meaning
-
-
+
+
+
+ Field Name
+
+
+ Value
+
+
+ Meaning
+
+
+
[[BindingObject]]
@@ -10281,29 +10932,28 @@ Object Environment Records
- The behaviour of the concrete specification methods for Object Environment Records is defined by the following algorithms.
HasBinding (
- _N_: a String,
+ _name_: a String,
): either a normal completion containing a Boolean or a throw completion
- for
- - an Object Environment Record _envRec_
+ - an Object Environment Record _envRecord_
- description
- - It determines if its associated binding object has a property whose name is _N_.
+ - It determines if its associated binding object has a property whose name is _name_.
- 1. Let _bindingObject_ be _envRec_.[[BindingObject]].
- 1. Let _foundBinding_ be ? HasProperty(_bindingObject_, _N_).
+ 1. Let _bindingObj_ be _envRecord_.[[BindingObject]].
+ 1. Let _foundBinding_ be ? HasProperty(_bindingObj_, _name_).
1. If _foundBinding_ is *false*, return *false*.
- 1. If _envRec_.[[IsWithEnvironment]] is *false*, return *true*.
- 1. Let _unscopables_ be ? Get(_bindingObject_, @@unscopables).
+ 1. If _envRecord_.[[IsWithEnvironment]] is *false*, return *true*.
+ 1. Let _unscopables_ be ? Get(_bindingObj_, %Symbol.unscopables%).
1. If _unscopables_ is an Object, then
- 1. Let _blocked_ be ToBoolean(? Get(_unscopables_, _N_)).
+ 1. Let _blocked_ be ToBoolean(? Get(_unscopables_, _name_)).
1. If _blocked_ is *true*, return *false*.
1. Return *true*.
@@ -10312,48 +10962,48 @@
CreateMutableBinding (
- _N_: a String,
- _D_: a Boolean,
+ _name_: a String,
+ _deletable_: a Boolean,
): either a normal completion containing ~unused~ or a throw completion
- for
- - an Object Environment Record _envRec_
+ - an Object Environment Record _envRecord_
- description
- - It creates in an Environment Record's associated binding object a property whose name is _N_ and initializes it to the value *undefined*. If _D_ is *true*, the new property's [[Configurable]] attribute is set to *true*; otherwise it is set to *false*.
+ - It creates in an Environment Record's associated binding object a property whose name is _name_ and initializes it to the value *undefined*. If _deletable_ is *true*, the new property's [[Configurable]] attribute is set to *true*; otherwise it is set to *false*.
- 1. Let _bindingObject_ be _envRec_.[[BindingObject]].
- 1. Perform ? DefinePropertyOrThrow(_bindingObject_, _N_, PropertyDescriptor { [[Value]]: *undefined*, [[Writable]]: *true*, [[Enumerable]]: *true*, [[Configurable]]: _D_ }).
+ 1. Let _bindingObj_ be _envRecord_.[[BindingObject]].
+ 1. Perform ? DefinePropertyOrThrow(_bindingObj_, _name_, PropertyDescriptor { [[Value]]: *undefined*, [[Writable]]: *true*, [[Enumerable]]: *true*, [[Configurable]]: _deletable_ }).
1. Return ~unused~.
- Normally _envRec_ will not have a binding for _N_ but if it does, the semantics of DefinePropertyOrThrow may result in an existing binding being replaced or shadowed or cause an abrupt completion to be returned.
+ Normally _envRecord_ will not have a binding for _name_ but if it does, the semantics of DefinePropertyOrThrow may result in an existing binding being replaced or shadowed or cause an abrupt completion to be returned.
- CreateImmutableBinding ( _N_, _S_ )
+ CreateImmutableBinding ( _name_, _strict_ )
The CreateImmutableBinding concrete method of an Object Environment Record is never used within this specification.
InitializeBinding (
- _N_: a String,
- _V_: an ECMAScript language value,
+ _name_: a String,
+ _value_: an ECMAScript language value,
): either a normal completion containing ~unused~ or a throw completion
- for
- - an Object Environment Record _envRec_
+ - an Object Environment Record _envRecord_
- description
- - It is used to set the bound value of the current binding of the identifier whose name is _N_ to the value _V_.
+ - It is used to set the bound value of the current binding of the identifier whose name is _name_ to the value _value_.
- 1. Perform ? _envRec_.SetMutableBinding (_N_, _V_, *false*).
+ 1. Perform ? _envRecord_.SetMutableBinding(_name_, _value_, *false*) .
1. Return ~unused~.
@@ -10364,23 +11014,23 @@
SetMutableBinding (
- _N_: a String,
- _V_: an ECMAScript language value,
- _S_: a Boolean,
+ _name_: a String,
+ _value_: an ECMAScript language value,
+ _strict_: a Boolean,
): either a normal completion containing ~unused~ or a throw completion
- for
- - an Object Environment Record _envRec_
+ - an Object Environment Record _envRecord_
- description
- - It attempts to set the value of the Environment Record's associated binding object's property whose name is _N_ to the value _V_. A property named _N_ normally already exists but if it does not or is not currently writable, error handling is determined by _S_.
+ - It attempts to set the value of the Environment Record's associated binding object's property whose name is _name_ to the value _value_. A property named _name_ normally already exists but if it does not or is not currently writable, error handling is determined by _strict_.
- 1. Let _bindingObject_ be _envRec_.[[BindingObject]].
- 1. Let _stillExists_ be ? HasProperty(_bindingObject_, _N_).
- 1. If _stillExists_ is *false* and _S_ is *true*, throw a *ReferenceError* exception.
- 1. Perform ? Set(_bindingObject_, _N_, _V_, _S_).
+ 1. Let _bindingObj_ be _envRecord_.[[BindingObject]].
+ 1. Let _stillExists_ be ? HasProperty(_bindingObj_, _name_).
+ 1. If _stillExists_ is *false* and _strict_ is *true*, throw a *ReferenceError* exception.
+ 1. Perform ? Set(_bindingObj_, _name_, _value_, _strict_).
1. Return ~unused~.
@@ -10388,42 +11038,43 @@
GetBindingValue (
- _N_: a String,
- _S_: a Boolean,
+ _name_: a String,
+ _strict_: a Boolean,
): either a normal completion containing an ECMAScript language value or a throw completion
- for
- - an Object Environment Record _envRec_
+ - an Object Environment Record _envRecord_
- description
- - It returns the value of its associated binding object's property whose name is _N_. The property should already exist but if it does not the result depends upon _S_.
+ - It returns the value of its associated binding object's property whose name is _name_. The property should already exist but if it does not the result depends upon _strict_.
- 1. Let _bindingObject_ be _envRec_.[[BindingObject]].
- 1. Let _value_ be ? HasProperty(_bindingObject_, _N_).
+ 1. Let _bindingObj_ be _envRecord_.[[BindingObject]].
+ 1. Let _value_ be ? HasProperty(_bindingObj_, _name_).
1. If _value_ is *false*, then
- 1. If _S_ is *false*, return *undefined*; otherwise throw a *ReferenceError* exception.
- 1. Return ? Get(_bindingObject_, _N_).
+ 1. If _strict_ is *false*, return *undefined*.
+ 1. Throw a *ReferenceError* exception.
+ 1. Return ? Get(_bindingObj_, _name_).
DeleteBinding (
- _N_: a String,
+ _name_: a String,
): either a normal completion containing a Boolean or a throw completion
- for
- - an Object Environment Record _envRec_
+ - an Object Environment Record _envRecord_
- description
- It can only delete bindings that correspond to properties of the environment object whose [[Configurable]] attribute have the value *true*.
- 1. Let _bindingObject_ be _envRec_.[[BindingObject]].
- 1. Return ? _bindingObject_.[[Delete]] (_N_).
+ 1. Let _bindingObj_ be _envRecord_.[[BindingObject]].
+ 1. Return ? _bindingObj_.[[Delete]](_name_) .
@@ -10431,7 +11082,7 @@
HasThisBinding ( ): *false*
- for
- - an Object Environment Record _envRec_
+ - an Object Environment Record _envRecord_
1. Return *false*.
@@ -10441,11 +11092,16 @@ HasThisBinding ( ): *false*
+
+ GetThisBinding ( )
+ The GetThisBinding concrete method of an Object Environment Record is never used within this specification.
+
+
HasSuperBinding ( ): *false*
- for
- - an Object Environment Record _envRec_
+ - an Object Environment Record _envRecord_
1. Return *false*.
@@ -10459,32 +11115,34 @@ HasSuperBinding ( ): *false*
WithBaseObject ( ): an Object or *undefined*
- for
- - an Object Environment Record _envRec_
+ - an Object Environment Record _envRecord_
- 1. If _envRec_.[[IsWithEnvironment]] is *true*, return _envRec_.[[BindingObject]].
- 1. Otherwise, return *undefined*.
+ 1. If _envRecord_.[[IsWithEnvironment]] is *true*, return _envRecord_.[[BindingObject]].
+ 1. Return *undefined*.
Function Environment Records
- A Function Environment Record is a Declarative Environment Record that is used to represent the top-level scope of a function and, if the function is not an |ArrowFunction|, provides a `this` binding. If a function is not an |ArrowFunction| function and references `super`, its Function Environment Record also contains the state that is used to perform `super` method invocations from within the function.
+ A Function Environment Record is a Declarative Environment Record that is used to represent the top-level scope of a function and, if the function is not an |ArrowFunction| function or |AsyncArrowFunction| function, provides a `this` binding. If a function is not an |ArrowFunction| function or |AsyncArrowFunction| function and references `super`, its Function Environment Record also contains the state that is used to perform `super` method invocations from within the function.
Function Environment Records have the additional state fields listed in
-
-
- Field Name
-
-
- Value
-
-
- Meaning
-
-
+
+
+
+ Field Name
+
+
+ Value
+
+
+ Meaning
+
+
+
[[ThisValue]]
@@ -10504,7 +11162,7 @@ Function Environment Records
~lexical~, ~initialized~, or ~uninitialized~
- If the value is ~lexical~, this is an |ArrowFunction| and does not have a local *this* value.
+ If the value is ~lexical~, this is an |ArrowFunction| or |AsyncArrowFunction| and does not have a local *this* value.
@@ -10523,7 +11181,7 @@ Function Environment Records
[[NewTarget]]
- an Object or *undefined*
+ a constructor or *undefined*
If this Environment Record was created by the [[Construct]] internal method, [[NewTarget]] is the value of the [[Construct]] _newTarget_ parameter. Otherwise, its value is *undefined*.
@@ -10531,61 +11189,25 @@ Function Environment Records
- Function Environment Records support all of the Declarative Environment Record methods listed in
-
-
-
-
- Method
-
-
- Purpose
-
-
-
-
- BindThisValue(V)
-
-
- Set the [[ThisValue]] and record that it has been initialized.
-
-
-
-
- GetThisBinding()
-
-
- Return the value of this Environment Record's `this` binding. Throws a *ReferenceError* if the `this` binding has not been initialized.
-
-
-
-
- GetSuperBase()
-
-
- Return the object that is the base for `super` property accesses bound in this Environment Record. The value *undefined* indicates that such accesses will produce runtime errors.
-
-
-
-
- The behaviour of the additional concrete specification methods for Function Environment Records is defined by the following algorithms:
+ Function Environment Records support all of the Declarative Environment Record methods listed in
-
+
BindThisValue (
- _V_: an ECMAScript language value,
- ): either a normal completion containing an ECMAScript language value or a throw completion
+ _envRecord_: a Function Environment Record,
+ _value_: an ECMAScript language value,
+ ): either a normal completion containing ~unused~ or a throw completion
- - for
- - a Function Environment Record _envRec_
+ - description
+ - It sets the _envRecord_.[[ThisValue]] and records that it has been initialized.
- 1. Assert: _envRec_.[[ThisBindingStatus]] is not ~lexical~.
- 1. If _envRec_.[[ThisBindingStatus]] is ~initialized~, throw a *ReferenceError* exception.
- 1. Set _envRec_.[[ThisValue]] to _V_.
- 1. Set _envRec_.[[ThisBindingStatus]] to ~initialized~.
- 1. Return _V_.
+ 1. Assert: _envRecord_.[[ThisBindingStatus]] is not ~lexical~.
+ 1. If _envRecord_.[[ThisBindingStatus]] is ~initialized~, throw a *ReferenceError* exception.
+ 1. Set _envRecord_.[[ThisValue]] to _value_.
+ 1. Set _envRecord_.[[ThisBindingStatus]] to ~initialized~.
+ 1. Return ~unused~.
@@ -10593,49 +11215,55 @@
HasThisBinding ( ): a Boolean
- for
- - a Function Environment Record _envRec_
+ - a Function Environment Record _envRecord_
- 1. If _envRec_.[[ThisBindingStatus]] is ~lexical~, return *false*; otherwise, return *true*.
+ 1. If _envRecord_.[[ThisBindingStatus]] is ~lexical~, return *false*.
+ 1. Return *true*.
-
- HasSuperBinding ( ): a Boolean
+
+ GetThisBinding ( ): either a normal completion containing an ECMAScript language value or a throw completion
- for
- - a Function Environment Record _envRec_
+ - a Function Environment Record _envRecord_
- 1. If _envRec_.[[ThisBindingStatus]] is ~lexical~, return *false*.
- 1. If _envRec_.[[FunctionObject]].[[HomeObject]] is *undefined*, return *false*; otherwise, return *true*.
+ 1. Assert: _envRecord_.[[ThisBindingStatus]] is not ~lexical~.
+ 1. If _envRecord_.[[ThisBindingStatus]] is ~uninitialized~, throw a *ReferenceError* exception.
+ 1. Return _envRecord_.[[ThisValue]].
-
- GetThisBinding ( ): either a normal completion containing an ECMAScript language value or a throw completion
+
+ HasSuperBinding ( ): a Boolean
- for
- - a Function Environment Record _envRec_
+ - a Function Environment Record _envRecord_
- 1. Assert: _envRec_.[[ThisBindingStatus]] is not ~lexical~.
- 1. If _envRec_.[[ThisBindingStatus]] is ~uninitialized~, throw a *ReferenceError* exception.
- 1. Return _envRec_.[[ThisValue]].
+ 1. If _envRecord_.[[ThisBindingStatus]] is ~lexical~, return *false*.
+ 1. If _envRecord_.[[FunctionObject]].[[HomeObject]] is *undefined*, return *false*.
+ 1. Return *true*.
-
- GetSuperBase ( ): either a normal completion containing either an Object, *null*, or *undefined*, or a throw completion
+
+
+ GetSuperBase (
+ _envRecord_: a Function Environment Record,
+ ): an Object, *null*, or *undefined*
+
- - for
- - a Function Environment Record _envRec_
+ - description
+ - It returns the object that is the base for `super` property accesses bound in _envRecord_. The value *undefined* indicates that such accesses will produce runtime errors.
- 1. Let _home_ be _envRec_.[[FunctionObject]].[[HomeObject]].
+ 1. Let _home_ be _envRecord_.[[FunctionObject]].[[HomeObject]].
1. If _home_ is *undefined*, return *undefined*.
- 1. Assert: _home_ is an Object.
- 1. Return ? _home_.[[GetPrototypeOf]] ().
+ 1. Assert: _home_ is an ordinary object.
+ 1. Return ! _home_.[[GetPrototypeOf]]().
@@ -10644,21 +11272,23 @@ GetSuperBase ( ): either a normal completion containing either an Object, *n
Global Environment Records
A Global Environment Record is used to represent the outer most scope that is shared by all of the ECMAScript |Script| elements that are processed in a common realm. A Global Environment Record provides the bindings for built-in globals (clause
A Global Environment Record is logically a single record but it is specified as a composite encapsulating an Object Environment Record and a Declarative Environment Record. The Object Environment Record has as its base object the global object of the associated Realm Record. This global object is the value returned by the Global Environment Record's GetThisBinding concrete method. The Object Environment Record component of a Global Environment Record contains the bindings for all built-in globals (clause
- Properties may be created directly on a global object. Hence, the Object Environment Record component of a Global Environment Record may contain both bindings created explicitly by |FunctionDeclaration|, |GeneratorDeclaration|, |AsyncFunctionDeclaration|, |AsyncGeneratorDeclaration|, or |VariableDeclaration| declarations and bindings created implicitly as properties of the global object. In order to identify which bindings were explicitly created using declarations, a Global Environment Record maintains a list of the names bound using its CreateGlobalVarBinding and CreateGlobalFunctionBinding concrete methods.
- Global Environment Records have the additional fields listed in
+ Properties may be created directly on a global object. Hence, the Object Environment Record component of a Global Environment Record may contain both bindings created explicitly by |FunctionDeclaration|, |GeneratorDeclaration|, |AsyncFunctionDeclaration|, |AsyncGeneratorDeclaration|, or |VariableDeclaration| declarations and bindings created implicitly as properties of the global object.
+ Global Environment Records have the additional fields listed in
-
-
- Field Name
-
-
- Value
-
-
- Meaning
-
-
+
+
+
+ Field Name
+
+
+ Value
+
+
+ Meaning
+
+
+
[[ObjectRecord]]
@@ -10692,256 +11322,165 @@ Global Environment Records
Contains bindings for all declarations in global code for the associated realm code except for |FunctionDeclaration|, |GeneratorDeclaration|, |AsyncFunctionDeclaration|, |AsyncGeneratorDeclaration|, and |VariableDeclaration| bindings.
-
-
- [[VarNames]]
-
-
- a List of Strings
-
-
- The string names bound by |FunctionDeclaration|, |GeneratorDeclaration|, |AsyncFunctionDeclaration|, |AsyncGeneratorDeclaration|, and |VariableDeclaration| declarations in global code for the associated realm.
-
-
-
-
-
-
- Method
-
-
- Purpose
-
-
-
-
- GetThisBinding()
-
-
- Return the value of this Environment Record's `this` binding.
-
-
-
-
- HasVarDeclaration (N)
-
-
- Determines if the argument identifier has a binding in this Environment Record that was created using a |VariableDeclaration|, |FunctionDeclaration|, |GeneratorDeclaration|, |AsyncFunctionDeclaration|, or |AsyncGeneratorDeclaration|.
-
-
-
-
- HasLexicalDeclaration (N)
-
-
- Determines if the argument identifier has a binding in this Environment Record that was created using a lexical declaration such as a |LexicalDeclaration| or a |ClassDeclaration|.
-
-
-
-
- HasRestrictedGlobalProperty (N)
-
-
- Determines if the argument is the name of a global object property that may not be shadowed by a global lexical binding.
-
-
-
-
- CanDeclareGlobalVar (N)
-
-
- Determines if a corresponding CreateGlobalVarBinding call would succeed if called for the same argument _N_.
-
-
-
-
- CanDeclareGlobalFunction (N)
-
-
- Determines if a corresponding CreateGlobalFunctionBinding call would succeed if called for the same argument _N_.
-
-
-
-
- CreateGlobalVarBinding(N, D)
-
-
- Used to create and initialize to *undefined* a global `var` binding in the [[ObjectRecord]] component of a Global Environment Record. The binding will be a mutable binding. The corresponding global object property will have attribute values appropriate for a `var`. The String value _N_ is the bound name. If _D_ is *true*, the binding may be deleted. Logically equivalent to CreateMutableBinding followed by a SetMutableBinding but it allows var declarations to receive special treatment.
-
-
-
-
- CreateGlobalFunctionBinding(N, V, D)
-
-
- Create and initialize a global `function` binding in the [[ObjectRecord]] component of a Global Environment Record. The binding will be a mutable binding. The corresponding global object property will have attribute values appropriate for a `function`. The String value _N_ is the bound name. _V_ is the initialization value. If the Boolean argument _D_ is *true*, the binding may be deleted. Logically equivalent to CreateMutableBinding followed by a SetMutableBinding but it allows function declarations to receive special treatment.
-
-
-
-
- The behaviour of the concrete specification methods for Global Environment Records is defined by the following algorithms.
HasBinding (
- _N_: a String,
+ _name_: a String,
): either a normal completion containing a Boolean or a throw completion
- for
- - a Global Environment Record _envRec_
+ - a Global Environment Record _envRecord_
- description
- It determines if the argument identifier is one of the identifiers bound by the record.
- 1. Let _DclRec_ be _envRec_.[[DeclarativeRecord]].
- 1. If ! _DclRec_.HasBinding(_N_) is *true*, return *true*.
- 1. Let _ObjRec_ be _envRec_.[[ObjectRecord]].
- 1. Return ? _ObjRec_.HasBinding (_N_).
+ 1. Let _declRecord_ be _envRecord_.[[DeclarativeRecord]].
+ 1. If ! _declRecord_.HasBinding(_name_) is *true*, return *true*.
+ 1. Let _objRecord_ be _envRecord_.[[ObjectRecord]].
+ 1. Return ? _objRecord_.HasBinding(_name_) .
CreateMutableBinding (
- _N_: a String,
- _D_: a Boolean,
+ _name_: a String,
+ _deletable_: a Boolean,
): either a normal completion containing ~unused~ or a throw completion
- for
- - a Global Environment Record _envRec_
+ - a Global Environment Record _envRecord_
- description
- - It creates a new mutable binding for the name _N_ that is uninitialized. The binding is created in the associated DeclarativeRecord. A binding for _N_ must not already exist in the DeclarativeRecord. If _D_ is *true*, the new binding is marked as being subject to deletion.
+ - It creates a new mutable binding for the name _name_ that is uninitialized. The binding is created in the associated DeclarativeRecord. A binding for _name_ must not already exist in the DeclarativeRecord. If _deletable_ is *true*, the new binding is marked as being subject to deletion.
- 1. Let _DclRec_ be _envRec_.[[DeclarativeRecord]].
- 1. If ! _DclRec_.HasBinding(_N_) is *true*, throw a *TypeError* exception.
- 1. Return ! _DclRec_.CreateMutableBinding(_N_, _D_).
+ 1. Let _declRecord_ be _envRecord_.[[DeclarativeRecord]].
+ 1. If ! _declRecord_.HasBinding(_name_) is *true*, throw a *TypeError* exception.
+ 1. Return ! _declRecord_.CreateMutableBinding(_name_, _deletable_).
CreateImmutableBinding (
- _N_: a String,
- _S_: a Boolean,
+ _name_: a String,
+ _strict_: a Boolean,
): either a normal completion containing ~unused~ or a throw completion
- for
- - a Global Environment Record _envRec_
+ - a Global Environment Record _envRecord_
- description
- - It creates a new immutable binding for the name _N_ that is uninitialized. A binding must not already exist in this Environment Record for _N_. If _S_ is *true*, the new binding is marked as a strict binding.
+ - It creates a new immutable binding for the name _name_ that is uninitialized. A binding must not already exist in this Environment Record for _name_. If _strict_ is *true*, the new binding is marked as a strict binding.
- 1. Let _DclRec_ be _envRec_.[[DeclarativeRecord]].
- 1. If ! _DclRec_.HasBinding(_N_) is *true*, throw a *TypeError* exception.
- 1. Return ! _DclRec_.CreateImmutableBinding(_N_, _S_).
+ 1. Let _declRecord_ be _envRecord_.[[DeclarativeRecord]].
+ 1. If ! _declRecord_.HasBinding(_name_) is *true*, throw a *TypeError* exception.
+ 1. Return ! _declRecord_.CreateImmutableBinding(_name_, _strict_).
InitializeBinding (
- _N_: a String,
- _V_: an ECMAScript language value,
+ _name_: a String,
+ _value_: an ECMAScript language value,
): either a normal completion containing ~unused~ or a throw completion
- for
- - a Global Environment Record _envRec_
+ - a Global Environment Record _envRecord_
- description
- - It is used to set the bound value of the current binding of the identifier whose name is _N_ to the value _V_. An uninitialized binding for _N_ must already exist.
+ - It is used to set the bound value of the current binding of the identifier whose name is _name_ to the value _value_. An uninitialized binding for _name_ must already exist.
- 1. Let _DclRec_ be _envRec_.[[DeclarativeRecord]].
- 1. If ! _DclRec_.HasBinding(_N_) is *true*, then
- 1. Return ! _DclRec_.InitializeBinding(_N_, _V_).
+ 1. Let _declRecord_ be _envRecord_.[[DeclarativeRecord]].
+ 1. If ! _declRecord_.HasBinding(_name_) is *true*, then
+ 1. Return ! _declRecord_.InitializeBinding(_name_, _value_).
1. Assert: If the binding exists, it must be in the Object Environment Record.
- 1. Let _ObjRec_ be _envRec_.[[ObjectRecord]].
- 1. Return ? _ObjRec_.InitializeBinding (_N_, _V_).
+ 1. Let _objRecord_ be _envRecord_.[[ObjectRecord]].
+ 1. Return ? _objRecord_.InitializeBinding(_name_, _value_) .
SetMutableBinding (
- _N_: a String,
- _V_: an ECMAScript language value,
- _S_: a Boolean,
+ _name_: a String,
+ _value_: an ECMAScript language value,
+ _strict_: a Boolean,
): either a normal completion containing ~unused~ or a throw completion
- for
- - a Global Environment Record _envRec_
+ - a Global Environment Record _envRecord_
- description
- - It attempts to change the bound value of the current binding of the identifier whose name is _N_ to the value _V_. If the binding is an immutable binding and _S_ is *true*, a *TypeError* is thrown. A property named _N_ normally already exists but if it does not or is not currently writable, error handling is determined by _S_.
+ - It attempts to change the bound value of the current binding of the identifier whose name is _name_ to the value _value_. If the binding is an immutable binding and _strict_ is *true*, a *TypeError* is thrown. A binding named _name_ normally already exists but if it does not or is not currently writable, error handling is determined by _strict_.
- 1. Let _DclRec_ be _envRec_.[[DeclarativeRecord]].
- 1. If ! _DclRec_.HasBinding(_N_) is *true*, then
- 1. Return ? _DclRec_.SetMutableBinding(_N_, _V_, _S_).
- 1. Let _ObjRec_ be _envRec_.[[ObjectRecord]].
- 1. Return ? _ObjRec_.SetMutableBinding (_N_, _V_, _S_).
+ 1. Let _declRecord_ be _envRecord_.[[DeclarativeRecord]].
+ 1. If ! _declRecord_.HasBinding(_name_) is *true*, then
+ 1. Return ? _declRecord_.SetMutableBinding(_name_, _value_, _strict_).
+ 1. Let _objRecord_ be _envRecord_.[[ObjectRecord]].
+ 1. Return ? _objRecord_.SetMutableBinding(_name_, _value_, _strict_) .
GetBindingValue (
- _N_: a String,
- _S_: a Boolean,
+ _name_: a String,
+ _strict_: a Boolean,
): either a normal completion containing an ECMAScript language value or a throw completion
- for
- - a Global Environment Record _envRec_
+ - a Global Environment Record _envRecord_
- description
- - It returns the value of its bound identifier whose name is _N_. If the binding is an uninitialized binding throw a *ReferenceError* exception. A property named _N_ normally already exists but if it does not or is not currently writable, error handling is determined by _S_.
+ - It returns the value of its bound identifier whose name is _name_. If the binding is an uninitialized binding, it will throw a *ReferenceError* exception. A binding named _name_ normally already exists but if it does not or is not currently writable, error handling is determined by _strict_.
- 1. Let _DclRec_ be _envRec_.[[DeclarativeRecord]].
- 1. If ! _DclRec_.HasBinding(_N_) is *true*, then
- 1. Return ? _DclRec_.GetBindingValue(_N_, _S_).
- 1. Let _ObjRec_ be _envRec_.[[ObjectRecord]].
- 1. Return ? _ObjRec_.GetBindingValue (_N_, _S_).
+ 1. Let _declRecord_ be _envRecord_.[[DeclarativeRecord]].
+ 1. If ! _declRecord_.HasBinding(_name_) is *true*, then
+ 1. Return ? _declRecord_.GetBindingValue(_name_, _strict_).
+ 1. Let _objRecord_ be _envRecord_.[[ObjectRecord]].
+ 1. Return ? _objRecord_.GetBindingValue(_name_, _strict_) .
DeleteBinding (
- _N_: a String,
+ _name_: a String,
): either a normal completion containing a Boolean or a throw completion
- for
- - a Global Environment Record _envRec_
+ - a Global Environment Record _envRecord_
- description
- It can only delete bindings that have been explicitly designated as being subject to deletion.
- 1. Let _DclRec_ be _envRec_.[[DeclarativeRecord]].
- 1. If ! _DclRec_.HasBinding(_N_) is *true*, then
- 1. Return ! _DclRec_.DeleteBinding(_N_).
- 1. Let _ObjRec_ be _envRec_.[[ObjectRecord]].
- 1. Let _globalObject_ be _ObjRec_.[[BindingObject]].
- 1. Let _existingProp_ be ? HasOwnProperty(_globalObject_, _N_).
- 1. If _existingProp_ is *true*, then
- 1. Let _status_ be ? _ObjRec_.DeleteBinding (_N_).
- 1. If _status_ is *true* and _envRec_.[[VarNames]] contains _N_, then
- 1. Remove _N_ from _envRec_.[[VarNames]].
- 1. Return _status_.
+ 1. Let _declRecord_ be _envRecord_.[[DeclarativeRecord]].
+ 1. If ! _declRecord_.HasBinding(_name_) is *true*, then
+ 1. Return ! _declRecord_.DeleteBinding(_name_).
+ 1. Let _objRecord_ be _envRecord_.[[ObjectRecord]].
+ 1. Let _globalObj_ be _objRecord_.[[BindingObject]].
+ 1. Let _existingProperty_ be ? HasOwnProperty(_globalObj_, _name_).
+ 1. If _existingProperty_ is *true*, then
+ 1. Return ? _objRecord_.DeleteBinding(_name_) .
1. Return *true*.
@@ -10950,7 +11489,7 @@
HasThisBinding ( ): *true*
- for
- - a Global Environment Record _envRec_
+ - a Global Environment Record _envRecord_
1. Return *true*.
@@ -10960,11 +11499,22 @@ HasThisBinding ( ): *true*
+
+ GetThisBinding ( ): a normal completion containing an Object
+
+ - for
+ - a Global Environment Record _envRecord_
+
+
+ 1. Return _envRecord_.[[GlobalThisValue]].
+
+
+
HasSuperBinding ( ): *false*
- for
- - a Global Environment Record _envRec_
+ - a Global Environment Record _envRecord_
1. Return *false*.
@@ -10978,82 +11528,47 @@ HasSuperBinding ( ): *false*
WithBaseObject ( ): *undefined*
- for
- - a Global Environment Record _envRec_
+ - a Global Environment Record _envRecord_
1. Return *undefined*.
-
- GetThisBinding ( ): a normal completion containing an Object
-
- - for
- - a Global Environment Record _envRec_
-
-
- 1. Return _envRec_.[[GlobalThisValue]].
-
-
-
-
-
- HasVarDeclaration (
- _N_: a String,
- ): a Boolean
-
-
- - for
- - a Global Environment Record _envRec_
-
- - description
- - It determines if the argument identifier has a binding in this record that was created using a |VariableStatement| or a |FunctionDeclaration|.
-
-
- 1. Let _varDeclaredNames_ be _envRec_.[[VarNames]].
- 1. If _varDeclaredNames_ contains _N_, return *true*.
- 1. Return *false*.
-
-
-
-
+
HasLexicalDeclaration (
- _N_: a String,
+ _envRecord_: a Global Environment Record,
+ _name_: a String,
): a Boolean
- - for
- - a Global Environment Record _envRec_
-
- description
- - It determines if the argument identifier has a binding in this record that was created using a lexical declaration such as a |LexicalDeclaration| or a |ClassDeclaration|.
+ - It determines if the argument identifier has a binding in _envRecord_ that was created using a lexical declaration such as a |LexicalDeclaration| or a |ClassDeclaration|.
- 1. Let _DclRec_ be _envRec_.[[DeclarativeRecord]].
- 1. Return ! _DclRec_.HasBinding(_N_).
+ 1. Let _declRecord_ be _envRecord_.[[DeclarativeRecord]].
+ 1. Return ! _declRecord_.HasBinding(_name_).
-
+
HasRestrictedGlobalProperty (
- _N_: a String,
+ _envRecord_: a Global Environment Record,
+ _name_: a String,
): either a normal completion containing a Boolean or a throw completion
- - for
- - a Global Environment Record _envRec_
-
- description
- It determines if the argument identifier is the name of a property of the global object that must not be shadowed by a global lexical binding.
- 1. Let _ObjRec_ be _envRec_.[[ObjectRecord]].
- 1. Let _globalObject_ be _ObjRec_.[[BindingObject]].
- 1. Let _existingProp_ be ? _globalObject_.[[GetOwnProperty]] (_N_).
- 1. If _existingProp_ is *undefined*, return *false*.
- 1. If _existingProp_.[[Configurable]] is *true*, return *false*.
+ 1. Let _objRecord_ be _envRecord_.[[ObjectRecord]].
+ 1. Let _globalObj_ be _objRecord_.[[BindingObject]].
+ 1. Let _existingProperty_ be ? _globalObj_.[[GetOwnProperty]](_name_) .
+ 1. If _existingProperty_ is *undefined*, return *false*.
+ 1. If _existingProperty_.[[Configurable]] is *true*, return *false*.
1. Return *true*.
@@ -11061,111 +11576,99 @@
-
+
CanDeclareGlobalVar (
- _N_: a String,
+ _envRecord_: a Global Environment Record,
+ _name_: a String,
): either a normal completion containing a Boolean or a throw completion
- - for
- - a Global Environment Record _envRec_
-
- description
- - It determines if a corresponding CreateGlobalVarBinding call would succeed if called for the same argument _N_. Redundant var declarations and var declarations for pre-existing global object properties are allowed.
+ - It determines if a corresponding CreateGlobalVarBinding call would succeed if called for the same argument _name_. Redundant var declarations and var declarations for pre-existing global object properties are allowed.
- 1. Let _ObjRec_ be _envRec_.[[ObjectRecord]].
- 1. Let _globalObject_ be _ObjRec_.[[BindingObject]].
- 1. Let _hasProperty_ be ? HasOwnProperty(_globalObject_, _N_).
+ 1. Let _objRecord_ be _envRecord_.[[ObjectRecord]].
+ 1. Let _globalObj_ be _objRecord_.[[BindingObject]].
+ 1. Let _hasProperty_ be ? HasOwnProperty(_globalObj_, _name_).
1. If _hasProperty_ is *true*, return *true*.
- 1. Return ? IsExtensible(_globalObject_).
+ 1. Return ? IsExtensible(_globalObj_).
-
+
CanDeclareGlobalFunction (
- _N_: a String,
+ _envRecord_: a Global Environment Record,
+ _name_: a String,
): either a normal completion containing a Boolean or a throw completion
- - for
- - a Global Environment Record _envRec_
-
- description
- - It determines if a corresponding CreateGlobalFunctionBinding call would succeed if called for the same argument _N_.
+ - It determines if a corresponding CreateGlobalFunctionBinding call would succeed if called for the same argument _name_.
- 1. Let _ObjRec_ be _envRec_.[[ObjectRecord]].
- 1. Let _globalObject_ be _ObjRec_.[[BindingObject]].
- 1. Let _existingProp_ be ? _globalObject_.[[GetOwnProperty]] (_N_).
- 1. If _existingProp_ is *undefined*, return ? IsExtensible(_globalObject_).
- 1. If _existingProp_.[[Configurable]] is *true*, return *true*.
- 1. If IsDataDescriptor(_existingProp_) is *true* and _existingProp_ has attribute values { [[Writable]]: *true*, [[Enumerable]]: *true* }, return *true*.
+ 1. Let _objRecord_ be _envRecord_.[[ObjectRecord]].
+ 1. Let _globalObj_ be _objRecord_.[[BindingObject]].
+ 1. Let _existingProperty_ be ? _globalObj_.[[GetOwnProperty]](_name_) .
+ 1. If _existingProperty_ is *undefined*, return ? IsExtensible(_globalObj_).
+ 1. If _existingProperty_.[[Configurable]] is *true*, return *true*.
+ 1. If IsDataDescriptor(_existingProperty_) is *true* and _existingProperty_ has attribute values { [[Writable]]: *true*, [[Enumerable]]: *true* }, return *true*.
1. Return *false*.
-
+
CreateGlobalVarBinding (
- _N_: a String,
- _D_: a Boolean,
+ _envRecord_: a Global Environment Record,
+ _name_: a String,
+ _deletable_: a Boolean,
): either a normal completion containing ~unused~ or a throw completion
- - for
- - a Global Environment Record _envRec_
-
- description
- - It creates and initializes a mutable binding in the associated Object Environment Record and records the bound name in the associated [[VarNames]] List. If a binding already exists, it is reused and assumed to be initialized.
+ - It creates and initializes a mutable binding in the associated Object Environment Record. If a binding already exists, it is reused and assumed to be initialized.
- 1. Let _ObjRec_ be _envRec_.[[ObjectRecord]].
- 1. Let _globalObject_ be _ObjRec_.[[BindingObject]].
- 1. Let _hasProperty_ be ? HasOwnProperty(_globalObject_, _N_).
- 1. Let _extensible_ be ? IsExtensible(_globalObject_).
+ 1. Let _objRecord_ be _envRecord_.[[ObjectRecord]].
+ 1. Let _globalObj_ be _objRecord_.[[BindingObject]].
+ 1. Let _hasProperty_ be ? HasOwnProperty(_globalObj_, _name_).
+ 1. Let _extensible_ be ? IsExtensible(_globalObj_).
1. If _hasProperty_ is *false* and _extensible_ is *true*, then
- 1. Perform ? _ObjRec_.CreateMutableBinding (_N_, _D_).
- 1. Perform ? _ObjRec_.InitializeBinding (_N_, *undefined*).
- 1. If _envRec_.[[VarNames]] does not contain _N_, then
- 1. Append _N_ to _envRec_.[[VarNames]].
+ 1. Perform ? _objRecord_.CreateMutableBinding(_name_, _deletable_) .
+ 1. Perform ? _objRecord_.InitializeBinding(_name_, *undefined*) .
1. Return ~unused~.
-
+
CreateGlobalFunctionBinding (
- _N_: a String,
- _V_: an ECMAScript language value,
- _D_: a Boolean,
+ _envRecord_: a Global Environment Record,
+ _name_: a String,
+ _value_: an ECMAScript function object,
+ _deletable_: a Boolean,
): either a normal completion containing ~unused~ or a throw completion
- - for
- - a Global Environment Record _envRec_
-
- description
- - It creates and initializes a mutable binding in the associated Object Environment Record and records the bound name in the associated [[VarNames]] List. If a binding already exists, it is replaced.
+ - It creates and initializes a mutable binding in the associated Object Environment Record. If a binding already exists, it is replaced.
- 1. Let _ObjRec_ be _envRec_.[[ObjectRecord]].
- 1. Let _globalObject_ be _ObjRec_.[[BindingObject]].
- 1. Let _existingProp_ be ? _globalObject_.[[GetOwnProperty]] (_N_).
- 1. If _existingProp_ is *undefined* or _existingProp_.[[Configurable]] is *true*, then
- 1. Let _desc_ be the PropertyDescriptor { [[Value]]: _V_, [[Writable]]: *true*, [[Enumerable]]: *true*, [[Configurable]]: _D_ }.
+ 1. Let _objRecord_ be _envRecord_.[[ObjectRecord]].
+ 1. Let _globalObj_ be _objRecord_.[[BindingObject]].
+ 1. Let _existingProperty_ be ? _globalObj_.[[GetOwnProperty]](_name_) .
+ 1. If _existingProperty_ is *undefined* or _existingProperty_.[[Configurable]] is *true*, then
+ 1. Let _propertyDesc_ be the PropertyDescriptor { [[Value]]: _value_, [[Writable]]: *true*, [[Enumerable]]: *true*, [[Configurable]]: _deletable_ }.
1. Else,
- 1. Let _desc_ be the PropertyDescriptor { [[Value]]: _V_ }.
- 1. Perform ? DefinePropertyOrThrow(_globalObject_, _N_, _desc_).
- 1. [id="step-createglobalfunctionbinding-set"] Perform ? Set(_globalObject_, _N_, _V_, *false*).
- 1. If _envRec_.[[VarNames]] does not contain _N_, then
- 1. Append _N_ to _envRec_.[[VarNames]].
+ 1. Let _propertyDesc_ be the PropertyDescriptor { [[Value]]: _value_ }.
+ 1. Perform ? DefinePropertyOrThrow(_globalObj_, _name_, _propertyDesc_).
+ 1. [id="step-createglobalfunctionbinding-set"] Perform ? Set(_globalObj_, _name_, _value_, *false*).
1. Return ~unused~.
- Global function declarations are always represented as own properties of the global object. If possible, an existing own property is reconfigured to have a standard set of attribute values. Step
+ Global function declarations are always represented as own properties of the global object. If possible, an existing own property is reconfigured to have a standard set of attribute values. Step
@@ -11173,69 +11676,40 @@
Module Environment Records
A Module Environment Record is a Declarative Environment Record that is used to represent the outer scope of an ECMAScript |Module|. In additional to normal mutable and immutable bindings, Module Environment Records also provide immutable import bindings which are bindings that provide indirect access to a target binding that exists in another Environment Record.
- Module Environment Records support all of the Declarative Environment Record methods listed in
-
-
-
-
- Method
-
-
- Purpose
-
-
-
-
- CreateImportBinding(N, M, N2)
-
-
- Create an immutable indirect binding in a Module Environment Record. The String value _N_ is the text of the bound name. _M_ is a Module Record, and _N2_ is a binding that exists in _M_'s Module Environment Record.
-
-
-
-
- GetThisBinding()
-
-
- Return the value of this Environment Record's `this` binding.
-
-
-
-
- The behaviour of the additional concrete specification methods for Module Environment Records are defined by the following algorithms:
+ Module Environment Records support all of the Declarative Environment Record methods listed in
GetBindingValue (
- _N_: a String,
- _S_: a Boolean,
+ _name_: a String,
+ _strict_: a Boolean,
): either a normal completion containing an ECMAScript language value or a throw completion
- for
- - a Module Environment Record _envRec_
+ - a Module Environment Record _envRecord_
- description
- - It returns the value of its bound identifier whose name is _N_. However, if the binding is an indirect binding the value of the target binding is returned. If the binding exists but is uninitialized a *ReferenceError* is thrown.
+ - It returns the value of its bound identifier whose name is _name_. However, if the binding is an indirect binding the value of the target binding is returned. If the binding exists but is uninitialized a *ReferenceError* is thrown.
- 1. Assert: _S_ is *true*.
- 1. Assert: _envRec_ has a binding for _N_.
- 1. If the binding for _N_ is an indirect binding, then
- 1. Let _M_ and _N2_ be the indirection values provided when this binding for _N_ was created.
- 1. Let _targetEnv_ be _M_.[[Environment]].
+ 1. Assert: _strict_ is *true*.
+ 1. Assert: _envRecord_ has a binding for _name_.
+ 1. If the binding for _name_ is an indirect binding, then
+ 1. Let _module_ and _targetName_ be the indirection values provided when this binding for _name_ was created.
+ 1. Let _targetEnv_ be _module_.[[Environment]].
1. If _targetEnv_ is ~empty~, throw a *ReferenceError* exception.
- 1. Return ? _targetEnv_.GetBindingValue (_N2_, *true*).
- 1. If the binding for _N_ in _envRec_ is an uninitialized binding, throw a *ReferenceError* exception.
- 1. Return the value currently bound to _N_ in _envRec_.
+ 1. Return ? _targetEnv_.GetBindingValue(_targetName_, *true*) .
+ 1. If the binding for _name_ in _envRecord_ is an uninitialized binding, throw a *ReferenceError* exception.
+ 1. Return the value currently bound to _name_ in _envRecord_.
- _S_ will always be *true* because a |Module| is always strict mode code.
+ _strict_ will always be *true* because a |Module| is always strict mode code.
- DeleteBinding ( _N_ )
+ DeleteBinding ( _name_ )
The DeleteBinding concrete method of a Module Environment Record is never used within this specification.
Module Environment Records are only used within strict code and an early error rule prevents the delete operator, in strict code, from being applied to a Reference Record that would resolve to a Module Environment Record binding. See
@@ -11246,7 +11720,7 @@ DeleteBinding ( _N_ )
HasThisBinding ( ): *true*
- for
- - a Module Environment Record _envRec_
+ - a Module Environment Record _envRecord_
1. Return *true*.
@@ -11260,32 +11734,30 @@ HasThisBinding ( ): *true*
GetThisBinding ( ): a normal completion containing *undefined*
- for
- - a Module Environment Record _envRec_
+ - a Module Environment Record _envRecord_
1. Return *undefined*.
-
+
CreateImportBinding (
- _N_: a String,
- _M_: a Module Record,
- _N2_: a String,
+ _envRecord_: a Module Environment Record,
+ _name_: a String,
+ _targetModule_: a Module Record,
+ _targetName_: a String,
): ~unused~
- - for
- - a Module Environment Record _envRec_
-
- description
- - It creates a new initialized immutable indirect binding for the name _N_. A binding must not already exist in this Environment Record for _N_. _N2_ is the name of a binding that exists in _M_'s Module Environment Record. Accesses to the value of the new binding will indirectly access the bound value of the target binding.
+ - It creates a new initialized immutable indirect binding for the name _name_. A binding must not already exist in _envRecord_ for _name_. _targetName_ is the name of a binding that exists in _targetModule_'s Module Environment Record. Accesses to the value of the new binding will indirectly access the bound value of the target binding.
- 1. Assert: _envRec_ does not already have a binding for _N_.
- 1. Assert: When _M_.[[Environment]] is instantiated, it will have a direct binding for _N2_.
- 1. Create an immutable indirect binding in _envRec_ for _N_ that references _M_ and _N2_ as its target binding and record that the binding is initialized.
+ 1. Assert: _envRecord_ does not already have a binding for _name_.
+ 1. Assert: When _targetModule_.[[Environment]] is instantiated, it will have a direct binding for _targetName_.
+ 1. Create an immutable indirect binding in _envRecord_ for _name_ that references _targetModule_ and _targetName_ as its target binding and record that the binding is initialized.
1. Return ~unused~.
@@ -11299,7 +11771,7 @@ Environment Record Operations
GetIdentifierReference (
- _env_: an Environment Record or *null*,
+ _envRecord_: an Environment Record or *null*,
_name_: a String,
_strict_: a Boolean,
): either a normal completion containing a Reference Record or a throw completion
@@ -11307,105 +11779,106 @@
- 1. If _env_ is *null*, then
+ 1. If _envRecord_ is *null*, then
1. Return the Reference Record { [[Base]]: ~unresolvable~, [[ReferencedName]]: _name_, [[Strict]]: _strict_, [[ThisValue]]: ~empty~ }.
- 1. Let _exists_ be ? _env_.HasBinding (_name_).
+ 1. Let _exists_ be ? _envRecord_.HasBinding(_name_) .
1. If _exists_ is *true*, then
- 1. Return the Reference Record { [[Base]]: _env_, [[ReferencedName]]: _name_, [[Strict]]: _strict_, [[ThisValue]]: ~empty~ }.
- 1. Else,
- 1. Let _outer_ be _env_.[[OuterEnv]].
- 1. Return ? GetIdentifierReference(_outer_, _name_, _strict_).
+ 1. Return the Reference Record { [[Base]]: _envRecord_, [[ReferencedName]]: _name_, [[Strict]]: _strict_, [[ThisValue]]: ~empty~ }.
+ 1. Let _outer_ be _envRecord_.[[OuterEnv]].
+ 1. Return ? GetIdentifierReference(_outer_, _name_, _strict_).
NewDeclarativeEnvironment (
- _E_: an Environment Record or *null*,
+ _outerEnv_: an Environment Record or *null*,
): a Declarative Environment Record
- 1. Let _env_ be a new Declarative Environment Record containing no bindings.
- 1. Set _env_.[[OuterEnv]] to _E_.
- 1. Return _env_.
+ 1. Let _envRecord_ be a new Declarative Environment Record containing no bindings.
+ 1. Set _envRecord_.[[OuterEnv]] to _outerEnv_.
+ 1. Set _envRecord_.[[DisposableResourceStack]] to a new empty List.
+ 1. Return _envRecord_.
NewObjectEnvironment (
- _O_: an Object,
- _W_: a Boolean,
- _E_: an Environment Record or *null*,
+ _obj_: an Object,
+ _isWithEnv_: a Boolean,
+ _outerEnv_: an Environment Record or *null*,
): an Object Environment Record
- 1. Let _env_ be a new Object Environment Record.
- 1. Set _env_.[[BindingObject]] to _O_.
- 1. Set _env_.[[IsWithEnvironment]] to _W_.
- 1. Set _env_.[[OuterEnv]] to _E_.
- 1. Return _env_.
+ 1. Let _envRecord_ be a new Object Environment Record.
+ 1. Set _envRecord_.[[BindingObject]] to _obj_.
+ 1. Set _envRecord_.[[IsWithEnvironment]] to _isWithEnv_.
+ 1. Set _envRecord_.[[OuterEnv]] to _outerEnv_.
+ 1. Return _envRecord_.
NewFunctionEnvironment (
- _F_: an ECMAScript function object,
+ _func_: an ECMAScript function object,
_newTarget_: an Object or *undefined*,
): a Function Environment Record
- 1. Let _env_ be a new Function Environment Record containing no bindings.
- 1. Set _env_.[[FunctionObject]] to _F_.
- 1. If _F_.[[ThisMode]] is ~lexical~, set _env_.[[ThisBindingStatus]] to ~lexical~.
- 1. Else, set _env_.[[ThisBindingStatus]] to ~uninitialized~.
- 1. Set _env_.[[NewTarget]] to _newTarget_.
- 1. Set _env_.[[OuterEnv]] to _F_.[[Environment]].
- 1. Return _env_.
+ 1. Let _envRecord_ be a new Function Environment Record containing no bindings.
+ 1. Set _envRecord_.[[FunctionObject]] to _func_.
+ 1. If _func_.[[ThisMode]] is ~lexical~, set _envRecord_.[[ThisBindingStatus]] to ~lexical~.
+ 1. Else, set _envRecord_.[[ThisBindingStatus]] to ~uninitialized~.
+ 1. Set _envRecord_.[[NewTarget]] to _newTarget_.
+ 1. Set _envRecord_.[[OuterEnv]] to _func_.[[Environment]].
+ 1. Set _envRecord_.[[DisposableResourceStack]] to a new empty List.
+ 1. Return _envRecord_.
NewGlobalEnvironment (
- _G_: an Object,
+ _obj_: an Object,
_thisValue_: an Object,
): a Global Environment Record
- 1. Let _objRec_ be NewObjectEnvironment(_G_, *false*, *null*).
- 1. Let _dclRec_ be NewDeclarativeEnvironment(*null*).
- 1. Let _env_ be a new Global Environment Record.
- 1. Set _env_.[[ObjectRecord]] to _objRec_.
- 1. Set _env_.[[GlobalThisValue]] to _thisValue_.
- 1. Set _env_.[[DeclarativeRecord]] to _dclRec_.
- 1. Set _env_.[[VarNames]] to a new empty List.
- 1. Set _env_.[[OuterEnv]] to *null*.
- 1. Return _env_.
+ 1. Let _objRecord_ be NewObjectEnvironment(_obj_, *false*, *null*).
+ 1. Let _declRecord_ be NewDeclarativeEnvironment(*null*).
+ 1. Let _envRecord_ be a new Global Environment Record.
+ 1. Set _envRecord_.[[ObjectRecord]] to _objRecord_.
+ 1. Set _envRecord_.[[GlobalThisValue]] to _thisValue_.
+ 1. Set _envRecord_.[[DeclarativeRecord]] to _declRecord_.
+ 1. Set _envRecord_.[[OuterEnv]] to *null*.
+ 1. Return _envRecord_.
NewModuleEnvironment (
- _E_: an Environment Record,
+ _outerEnv_: a Global Environment Record,
): a Module Environment Record
- 1. Let _env_ be a new Module Environment Record containing no bindings.
- 1. Set _env_.[[OuterEnv]] to _E_.
- 1. Return _env_.
+ 1. Let _envRecord_ be a new Module Environment Record containing no bindings.
+ 1. Set _envRecord_.[[OuterEnv]] to _outerEnv_.
+ 1. Set _envRecord_.[[DisposableResourceStack]] to a new empty List.
+ 1. Return _envRecord_.
@@ -11462,34 +11935,34 @@ PrivateEnvironment Record Operations
NewPrivateEnvironment (
- _outerPrivEnv_: a PrivateEnvironment Record or *null*,
+ _outerPrivateEnv_: a PrivateEnvironment Record or *null*,
): a PrivateEnvironment Record
1. Let _names_ be a new empty List.
- 1. Return the PrivateEnvironment Record { [[OuterPrivateEnvironment]]: _outerPrivEnv_, [[Names]]: _names_ }.
+ 1. Return the PrivateEnvironment Record { [[OuterPrivateEnvironment]]: _outerPrivateEnv_, [[Names]]: _names_ }.
ResolvePrivateIdentifier (
- _privEnv_: a PrivateEnvironment Record,
+ _privateEnv_: a PrivateEnvironment Record,
_identifier_: a String,
): a Private Name
- 1. Let _names_ be _privEnv_.[[Names]].
- 1. For each Private Name _pn_ of _names_, do
- 1. If _pn_.[[Description]] is _identifier_, then
- 1. Return _pn_.
- 1. Let _outerPrivEnv_ be _privEnv_.[[OuterPrivateEnvironment]].
- 1. Assert: _outerPrivEnv_ is not *null*.
- 1. Return ResolvePrivateIdentifier(_outerPrivEnv_, _identifier_).
+ 1. Let _names_ be _privateEnv_.[[Names]].
+ 1. For each Private Name _privateName_ of _names_, do
+ 1. If _privateName_.[[Description]] is _identifier_, then
+ 1. Return _privateName_.
+ 1. Let _outerPrivateEnv_ be _privateEnv_.[[OuterPrivateEnvironment]].
+ 1. Assert: _outerPrivateEnv_ is not *null*.
+ 1. Return ResolvePrivateIdentifier(_outerPrivateEnv_, _identifier_).
@@ -11501,17 +11974,19 @@ Realms
A realm is represented in this specification as a Realm Record with the fields specified in
-
-
- Field Name
-
-
- Value
-
-
- Meaning
-
-
+
+
+
+ Field Name
+
+
+ Value
+
+
+ Meaning
+
+
+
[[AgentSignifier]]
@@ -11539,7 +12014,7 @@ Realms
[[GlobalObject]]
- an Object or *undefined*
+ an Object
The global object for this realm
@@ -11573,10 +12048,10 @@ Realms
[[LoadedModules]]
- a List of Records with fields [[Specifier]] (a String) and [[Module]] (a Module Record)
+ a List of LoadedModuleRequest Records
- A map from the specifier strings imported by this realm to the resolved Module Record. The list does not contain two different Records with the same [[Specifier]].
+ A map from the specifier strings imported by this realm to the resolved Module Record. The list does not contain two different Records _r1_ and _r2_ such that ModuleRequestsEqual(_r1_, _r2_) is *true*.
As mentioned in HostLoadImportedModule (
@@ -11604,15 +12079,13 @@ InitializeHostDefinedRealm ( ): either a normal completion containing ~unuse
1. Let _realm_ be a new Realm Record.
1. Perform CreateIntrinsics(_realm_).
1. Set _realm_.[[AgentSignifier]] to AgentSignifier().
- 1. Set _realm_.[[GlobalObject]] to *undefined*.
- 1. Set _realm_.[[GlobalEnv]] to *undefined*.
1. Set _realm_.[[TemplateMap]] to a new empty List.
1. Let _newContext_ be a new execution context.
1. Set the Function of _newContext_ to *null*.
1. Set the Realm of _newContext_ to _realm_.
1. Set the ScriptOrModule of _newContext_ to *null*.
1. Push _newContext_ onto the execution context stack; _newContext_ is now the running execution context.
- 1. If the host requires use of an exotic object to serve as _realm_'s global object, then
+ 1. If the host requires use of a specific object to serve as _realm_'s global object, then
1. Let _global_ be such an object created in a host-defined manner.
1. Else,
1. Let _global_ be OrdinaryObjectCreate(_realm_.[[Intrinsics]].[[%Object.prototype%]]).
@@ -11631,15 +12104,15 @@ InitializeHostDefinedRealm ( ): either a normal completion containing ~unuse
CreateIntrinsics (
- _realmRec_: a Realm Record,
+ _realmRecord_: a Realm Record,
): ~unused~
- 1. Set _realmRec_.[[Intrinsics]] to a new Record.
- 1. [declared="steps,name,length,slots,prototype"] Set fields of _realmRec_.[[Intrinsics]] with the values listed in
@@ -11647,17 +12120,17 @@
SetDefaultGlobalBindings (
- _realmRec_: a Realm Record,
+ _realmRecord_: a Realm Record,
): either a normal completion containing ~unused~ or a throw completion
- 1. Let _global_ be _realmRec_.[[GlobalObject]].
+ 1. Let _global_ be _realmRecord_.[[GlobalObject]].
1. For each property of the Global Object specified in clause
@@ -11670,14 +12143,16 @@ Execution Contexts
An execution context contains whatever implementation specific state is necessary to track the execution progress of its associated code. Each execution context has at least the state components listed in
-
-
- Component
-
-
- Purpose
-
-
+
+
+
+ Component
+
+
+ Purpose
+
+
+
code evaluation state
@@ -11717,14 +12192,16 @@ Execution Contexts
ECMAScript code execution contexts have the additional state components listed in
-
-
- Component
-
-
- Purpose
-
-
+
+
+
+ Component
+
+
+ Purpose
+
+
+
LexicalEnvironment
@@ -11755,14 +12232,16 @@ Execution Contexts
Execution contexts representing the evaluation of Generators have the additional state components listed in
-
-
- Component
-
-
- Purpose
-
-
+
+
+
+ Component
+
+
+ Purpose
+
+
+
Generator
@@ -11785,8 +12264,9 @@ GetActiveScriptOrModule ( ): a Script Record, a Module Record, or *null*
1. If the execution context stack is empty, return *null*.
- 1. Let _ec_ be the topmost execution context on the execution context stack whose ScriptOrModule component is not *null*.
- 1. If no such execution context exists, return *null*. Otherwise, return _ec_'s ScriptOrModule.
+ 1. Let _executionContext_ be the topmost execution context on the execution context stack whose ScriptOrModule component is not *null*.
+ 1. If no such execution context exists, return *null*.
+ 1. Return _executionContext_'s ScriptOrModule.
@@ -11794,19 +12274,19 @@ GetActiveScriptOrModule ( ): a Script Record, a Module Record, or *null*
ResolveBinding (
_name_: a String,
- optional _env_: an Environment Record or *undefined*,
+ optional _envRecord_: an Environment Record or *undefined*,
): either a normal completion containing a Reference Record or a throw completion
- description
- - It is used to determine the binding of _name_. _env_ can be used to explicitly provide the Environment Record that is to be searched for the binding.
+ - It is used to determine the binding of _name_. _envRecord_ can be used to explicitly provide the Environment Record that is to be searched for the binding.
- 1. If _env_ is not present or _env_ is *undefined*, then
- 1. Set _env_ to the running execution context's LexicalEnvironment.
- 1. Assert: _env_ is an Environment Record.
+ 1. If _envRecord_ is not present or _envRecord_ is *undefined*, then
+ 1. Set _envRecord_ to the running execution context's LexicalEnvironment.
+ 1. Assert: _envRecord_ is an Environment Record.
1. Let _strict_ be IsStrict(the syntactic production that is being evaluated).
- 1. Return ? GetIdentifierReference(_env_, _name_, _strict_).
+ 1. Return ? GetIdentifierReference(_envRecord_, _name_, _strict_).
The result of ResolveBinding is always a Reference Record whose [[ReferencedName]] field is _name_.
@@ -11820,13 +12300,13 @@ GetThisEnvironment ( ): an Environment Record
- It finds the Environment Record that currently supplies the binding of the keyword `this`.
- 1. Let _env_ be the running execution context's LexicalEnvironment.
+ 1. Let _envRecord_ be the running execution context's LexicalEnvironment.
1. [id="step-getthisenvironment-loop"] Repeat,
- 1. Let _exists_ be _env_.HasThisBinding().
- 1. If _exists_ is *true*, return _env_.
- 1. Let _outer_ be _env_.[[OuterEnv]].
+ 1. Let _exists_ be _envRecord_.HasThisBinding().
+ 1. If _exists_ is *true*, return _envRecord_.
+ 1. Let _outer_ be _envRecord_.[[OuterEnv]].
1. Assert: _outer_ is not *null*.
- 1. Set _env_ to _outer_.
+ 1. Set _envRecord_ to _outer_.
The loop in step
@@ -11840,8 +12320,8 @@ ResolveThisBinding ( ): either a normal completion containing an ECMAScript
- It determines the binding of the keyword `this` using the LexicalEnvironment of the running execution context.
- 1. Let _envRec_ be GetThisEnvironment().
- 1. Return ? _envRec_.GetThisBinding().
+ 1. Let _envRecord_ be GetThisEnvironment().
+ 1. Return ? _envRecord_.GetThisBinding().
@@ -11852,9 +12332,9 @@ GetNewTarget ( ): an Object or *undefined*
- It determines the NewTarget value using the LexicalEnvironment of the running execution context.
- 1. Let _envRec_ be GetThisEnvironment().
- 1. Assert: _envRec_ has a [[NewTarget]] field.
- 1. Return _envRec_.[[NewTarget]].
+ 1. Let _envRecord_ be GetThisEnvironment().
+ 1. Assert: _envRecord_ has a [[NewTarget]] field.
+ 1. Return _envRecord_.[[NewTarget]].
@@ -11869,6 +12349,49 @@ GetGlobalObject ( ): an Object
1. Return _currentRealm_.[[GlobalObject]].
+
+
+
+ RunSuspendedContext (
+ _context_: an execution context,
+ _completionRecord_: a Completion Record,
+ ): either a normal completion containing either an ECMAScript language value or ~unused~, or an abrupt completion
+
+
+ - description
+ - It resumes _context_ (sending it _completionRecord_ as the resumption value), and waits for the result.
+
+
+ 1. Let _callerContext_ be the running execution context.
+ 1. Suspend _callerContext_.
+ 1. Push _context_ onto the execution context stack; _context_ is now the running execution context.
+ 1. Resume the suspended evaluation of _context_ using _completionRecord_ as the result of the operation that suspended it. Let _result_ be the Completion Record returned by the resumed computation.
+ 1. Assert: When we reach this step, _context_ has already been removed from the execution context stack and _callerContext_ is the running execution context again.
+ 1. Return Completion(_result_).
+
+
+
+
+
+ RunCallerContext (
+ _value_: an ECMAScript language value or ~empty~,
+ ): a Completion Record
+
+
+ - description
+ - It resumes the caller context (sending it _value_ as the resumption value), and waits for the result, if any.
+
+
+ 1. Let _genContext_ be the running execution context.
+ 1. Remove _genContext_ from the execution context stack and restore the execution context that is at the top of the execution context stack as the running execution context.
+ 1. Let _callerContext_ be the running execution context.
+ 1. Resume _callerContext_, passing NormalCompletion(_value_).
+ 1. NOTE: The above step transfers control to _callerContext_ and pauses. The only way for it to un-pause and have control proceed to the subsequent steps in this algorithm is for _genContext_ to be resumed again, which might never happen.
+ 1. Assert: _genContext_ is the running execution context.
+ 1. Let _result_ be the Completion Record with which _genContext_ was just resumed.
+ 1. Return Completion(_result_).
+
+
@@ -11880,7 +12403,7 @@ Jobs and Host Operations to Enqueue Jobs
- At some future point in time, when there is no running context in the agent for which the job is scheduled and that agent's execution context stack is empty, the implementation must:
- Perform any host-defined preparation steps.
- - Invoke the Job Abstract Closure.
+ Invoke the Job Abstract Closure.- Perform any host-defined cleanup steps, after which the execution context stack must be empty.
@@ -11896,7 +12419,7 @@ Jobs and Host Operations to Enqueue Jobs
At any particular time, _scriptOrModule_ (a Script Record, a Module Record, or *null*) is the active script or module if all of the following conditions are true:
- GetActiveScriptOrModule() is _scriptOrModule_.
- - If _scriptOrModule_ is a Script Record or Module Record, let _ec_ be the topmost execution context on the execution context stack whose ScriptOrModule component is _scriptOrModule_. The Realm component of _ec_ is _scriptOrModule_.[[Realm]].
+ - If _scriptOrModule_ is a Script Record or Module Record, let _executionContext_ be the topmost execution context on the execution context stack whose ScriptOrModule component is _scriptOrModule_. The Realm component of _executionContext_ is _scriptOrModule_.[[Realm]].
At any particular time, an execution is prepared to evaluate ECMAScript code if all of the following conditions are true:
@@ -11914,24 +12437,26 @@ Jobs and Host Operations to Enqueue Jobs
JobCallback Records
- A JobCallback Record is a Record value used to store a function object and a host-defined value. Function objects that are invoked via a Job enqueued by the host may have additional host-defined context. To propagate the state, Job Abstract Closures should not capture and call function objects directly. Instead, use HostMakeJobCallback and HostCallJobCallback.
+ A JobCallback Record is a Record used to store a function object and a host-defined value. Function objects that are invoked via a Job enqueued by the host may have additional host-defined context. To propagate the state, Job Abstract Closures should not capture and call function objects directly. Instead, use HostMakeJobCallback and HostCallJobCallback.
The WHATWG HTML specification (https://html.spec.whatwg.org/), for example, uses the host-defined value to propagate the incumbent settings object for Promise callbacks.
JobCallback Records have the fields listed in
-
-
- Field Name
-
-
- Value
-
-
- Meaning
-
-
+
+
+
+ Field Name
+
+
+ Value
+
+
+ Meaning
+
+
+
[[Callback]]
@@ -11984,15 +12509,15 @@
HostCallJobCallback (
_jobCallback_: a JobCallback Record,
- _V_: an ECMAScript language value,
- _argumentsList_: a List of ECMAScript language values,
+ _thisValue_: an ECMAScript language value,
+ _argList_: a List of ECMAScript language values,
): either a normal completion containing an ECMAScript language value or a throw completion
An implementation of HostCallJobCallback must conform to the following requirements:
- - It must perform and return the result of Call(_jobCallback_.[[Callback]], _V_, _argumentsList_).
+ - It must perform and return the result of Call(_jobCallback_.[[Callback]], _thisValue_, _argList_).
This requirement means that hosts cannot change the [[Call]] behaviour of function objects defined in this specification.
@@ -12000,7 +12525,7 @@
The default implementation of HostCallJobCallback performs the following steps when called:
1. Assert: IsCallable(_jobCallback_.[[Callback]]) is *true*.
- 1. Return ? Call(_jobCallback_.[[Callback]], _V_, _argumentsList_).
+ 1. Return ? Call(_jobCallback_.[[Callback]], _thisValue_, _argList_).
ECMAScript hosts that are not web browsers must use the default implementation of HostCallJobCallback.
@@ -12071,15 +12596,17 @@ Agents
An agent signifier is a globally-unique opaque value used to identify an Agent.
-
- Field Name
- Value
- Meaning
-
+
+
+ Field Name
+ Value
+ Meaning
+
+
[[LittleEndian]]
a Boolean
- The default value computed for the isLittleEndian parameter when it is needed by the algorithms GetValueFromBuffer and SetValueInBuffer. The choice is implementation-defined and should be the alternative that is most efficient for the implementation. Once the value has been observed it cannot change.
+ The default value computed for the isLittleEndian parameter when it is needed by the algorithms GetValueFromBuffer and SetValueInBuffer. The choice is implementation-defined and should be the alternative that is most efficient for the implementation.
[[CanBlock]]
@@ -12116,13 +12643,25 @@ Agents
a List of either Objects or Symbols
Initially a new empty List, representing the list of objects and/or symbols to be kept alive until the end of the current Job
+
+ [[ModuleAsyncEvaluationCount]]
+ an integer
+ Initially 0, used to assign unique incrementing values to the [[AsyncEvaluationOrder]] field of modules that are asynchronous or have asynchronous dependencies.
+
+
+ [[GlobalSymbolRegistry]]
+ a List of GlobalSymbolRegistry Records
+ Initially a new empty List, representing the list of Symbol values produced by Symbol.for .
+
- Once the values of [[Signifier]], [[IsLockFree1]], and [[IsLockFree2]] have been observed by any agent in the agent cluster they cannot change.
+ The values of [[LittleEndian]], [[Signifier]], [[IsLockFree1]], [[IsLockFree2]], and [[IsLockFree8]] cannot change.
+
+ The [[GlobalSymbolRegistry]] List is append-only and never reassigned.
- The values of [[IsLockFree1]] and [[IsLockFree2]] are not necessarily determined by the hardware, but may also reflect implementation choices that can vary over time and between ECMAScript implementations.
+ The values of [[IsLockFree1]], [[IsLockFree2]], and [[IsLockFree8]] are not necessarily determined by the hardware, but may also reflect implementation choices that can vary over time and between ECMAScript implementations.
There is no [[IsLockFree4]] field: 4-byte atomic operations are always lock-free.
@@ -12140,8 +12679,8 @@ AgentSignifier ( ): an agent signifier
- 1. Let _AR_ be the Agent Record of the surrounding agent.
- 1. Return _AR_.[[Signifier]].
+ 1. Let _agentRecord_ be the Agent Record of the surrounding agent.
+ 1. Return _agentRecord_.[[Signifier]].
@@ -12150,13 +12689,28 @@ AgentCanSuspend ( ): a Boolean
- 1. Let _AR_ be the Agent Record of the surrounding agent.
- 1. Return _AR_.[[CanBlock]].
+ 1. Let _agentRecord_ be the Agent Record of the surrounding agent.
+ 1. Return _agentRecord_.[[CanBlock]].
In some environments it may not be reasonable for a given agent to suspend. For example, in a web browser environment, it may be reasonable to disallow suspending a document's main event handling thread, while still allowing workers' event handling threads to suspend.
+
+
+ IncrementModuleAsyncEvaluationCount ( ): a non-negative integer
+
+
+
+ 1. Let _agentRecord_ be the Agent Record of the surrounding agent.
+ 1. Let _count_ be _agentRecord_.[[ModuleAsyncEvaluationCount]].
+ 1. Set _agentRecord_.[[ModuleAsyncEvaluationCount]] to _count_ + 1.
+ 1. Return _count_.
+
+
+ This value is only used to keep track of the relative evaluation order between pending modules. An implementation may unobservably reset [[ModuleAsyncEvaluationCount]] to 0 whenever there are no pending modules.
+
+
@@ -12182,7 +12736,7 @@ Agent Clusters
If different agents within an agent cluster have different values of [[LittleEndian]] it becomes hard to use shared memory for multi-byte data.
- All agents within a cluster must have the same values for the [[IsLockFree1]] field in their respective Agent Records; similarly for the [[IsLockFree2]] field.
+ All agents within a cluster must have the same values for the [[IsLockFree1]] field in their respective Agent Records; similarly for the [[IsLockFree2]] and [[IsLockFree8]] fields.
All agents within a cluster must have different values for the [[Signifier]] field in their respective Agent Records.
@@ -12241,7 +12795,7 @@ Processing Model of WeakRef and FinalizationRegistry Targets
Objectives
- This specification does not make any guarantees that any object or symbol will be garbage collected. Objects or symbols which are not live may be released after long periods of time, or never at all. For this reason, this specification uses the term "may" when describing behaviour triggered by garbage collection.
+ This specification does not make any guarantees that any object or symbol will be garbage collected. Objects or symbols which are not live may be released after long periods of time, or never at all. For this reason, this specification uses the term “may” when describing behaviour triggered by garbage collection.
The semantics of WeakRefs and FinalizationRegistrys is based on two operations which happen at particular points in time:
@@ -12263,7 +12817,7 @@ Objectives
Liveness
- For some set of objects and/or symbols _S_ a hypothetical WeakRef-oblivious execution with respect to _S_ is an execution whereby the abstract operation WeakRefDeref of a WeakRef whose referent is an element of _S_ always returns *undefined*.
+ For some set of objects and/or symbols _objSet_ a hypothetical WeakRef-oblivious execution with respect to _objSet_ is an execution whereby the abstract operation WeakRefDeref of a WeakRef whose referent is an element of _objSet_ always returns *undefined*.
WeakRef-obliviousness, together with liveness, capture two notions. One, that a WeakRef itself does not keep its referent alive. Two, that cycles in liveness does not imply that a value is live. To be concrete, if determining _v_'s liveness depends on determining the liveness of a WeakRef referent, _r_, _r_'s liveness cannot assume _v_'s liveness, which would be circular reasoning.
@@ -12275,14 +12829,14 @@ Liveness
Colloquially, we say that an individual object or symbol is live if every set containing it is live.
- At any point during evaluation, a set of objects and/or symbols _S_ is considered live if either of the following conditions is met:
+ At any point during evaluation, a set of objects and/or symbols _objSet_ is considered live if either of the following conditions is met:
-
- Any element in _S_ is included in any agent's [[KeptAlive]] List.
+ Any element in _objSet_ is included in any agent's [[KeptAlive]] List.
-
- There exists a valid future hypothetical WeakRef-oblivious execution with respect to _S_ that observes the identity of any value in _S_.
+ There exists a valid future hypothetical WeakRef-oblivious execution with respect to _objSet_ that observes the identity of any value in _objSet_.
@@ -12303,18 +12857,19 @@ Liveness
Execution
- At any time, if a set of objects and/or symbols _S_ is not live, an ECMAScript implementation may perform the following steps atomically:
+ At any time, if a set of objects and/or symbols _objSet_ is not live, an ECMAScript implementation may perform the following steps atomically:
- 1. For each element _value_ of _S_, do
+ 1. For each element _value_ of _objSet_, do
1. For each WeakRef _ref_ such that _ref_.[[WeakRefTarget]] is _value_, do
1. Set _ref_.[[WeakRefTarget]] to ~empty~.
- 1. For each FinalizationRegistry _fg_ such that _fg_.[[Cells]] contains a Record _cell_ such that _cell_.[[WeakRefTarget]] is _value_, do
+ 1. For each FinalizationRegistry _finalizationRegistry_ such that _finalizationRegistry_.[[Cells]] contains a Record _cell_ such that _cell_.[[WeakRefTarget]] is _value_, do
1. Set _cell_.[[WeakRefTarget]] to ~empty~.
- 1. Optionally, perform HostEnqueueFinalizationRegistryCleanupJob(_fg_).
- 1. For each WeakMap _map_ such that _map_.[[WeakMapData]] contains a Record _r_ such that _r_.[[Key]] is _value_, do
- 1. Set _r_.[[Key]] to ~empty~.
- 1. Set _r_.[[Value]] to ~empty~.
+ 1. Let _enqueueCleanup_ be an implementation-defined choice of either *true* or *false*.
+ 1. If _enqueueCleanup_ is *true*, perform HostEnqueueFinalizationRegistryCleanupJob(_finalizationRegistry_).
+ 1. For each WeakMap _map_ such that _map_.[[WeakMapData]] contains a Record _entry_ such that _entry_.[[Key]] is _value_, do
+ 1. Set _entry_.[[Key]] to ~empty~.
+ 1. Set _entry_.[[Value]] to ~empty~.
1. For each WeakSet _set_ such that _set_.[[WeakSetData]] contains _value_, do
1. Replace the element of _set_.[[WeakSetData]] whose value is _value_ with an element whose value is ~empty~.
@@ -12330,7 +12885,7 @@ Execution
Implementations are not obligated to empty WeakRefs for maximal sets of non-live objects or symbols.
- If an implementation chooses a non-live set _S_ in which to empty WeakRefs, this definition requires that it empties WeakRefs for all values in _S_ simultaneously. In other words, it is not conformant for an implementation to empty a WeakRef pointing to a value _v_ without emptying out other WeakRefs that, if not emptied, could result in an execution that observes the value of _v_.
+ If an implementation chooses a non-live set _objSet_ in which to empty WeakRefs, this definition requires that it empties WeakRefs for all values in _objSet_ simultaneously. In other words, it is not conformant for an implementation to empty a WeakRef pointing to a value _v_ without emptying out other WeakRefs that, if not emptied, could result in an execution that observes the value of _v_.
@@ -12409,16 +12964,16 @@
CanBeHeldWeakly (
- _v_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): a Boolean
- description
- - It returns *true* if and only if _v_ is suitable for use as a weak reference. Only values that are suitable for use as a weak reference may be a key of a WeakMap, an element of a WeakSet, the target of a WeakRef, or one of the targets of a FinalizationRegistry.
+ - It returns *true* if and only if _arg_ is suitable for use as a weak reference. Only values that are suitable for use as a weak reference may be a key of a WeakMap, an element of a WeakSet, the target of a WeakRef, or one of the targets of a FinalizationRegistry.
- 1. If _v_ is an Object, return *true*.
- 1. If _v_ is a Symbol and KeyForSymbol(_v_) is *undefined*, return *true*.
+ 1. If _arg_ is an Object, return *true*.
+ 1. If _arg_ is a Symbol and KeyForSymbol(_arg_) is *undefined*, return *true*.
1. Return *false*.
@@ -12432,31 +12987,31 @@ Ordinary and Exotic Objects Behaviours
Ordinary Object Internal Methods and Internal Slots
- All ordinary objects have an internal slot called [[Prototype]]. The value of this internal slot is either *null* or an object and is used for implementing inheritance. Assume a property named _P_ is missing from an ordinary object _O_ but exists on its [[Prototype]] object. If _P_ refers to a data property on the [[Prototype]] object, _O_ inherits it for get access, making it behave as if _P_ was a property of _O_. If _P_ refers to a writable data property on the [[Prototype]] object, set access of _P_ on _O_ creates a new data property named _P_ on _O_. If _P_ refers to a non-writable data property on the [[Prototype]] object, set access of _P_ on _O_ fails. If _P_ refers to an accessor property on the [[Prototype]] object, the accessor is inherited by _O_ for both get access and set access.
+ All ordinary objects have an internal slot called [[Prototype]]. The value of this internal slot is either *null* or an object and is used for implementing inheritance. Assume a property named _propertyKey_ is missing from an ordinary object _obj_ but exists on its [[Prototype]] object. If _propertyKey_ refers to a data property on the [[Prototype]] object, _obj_ inherits it for get access, making it behave as if _propertyKey_ was a property of _obj_. If _propertyKey_ refers to a writable data property on the [[Prototype]] object, set access of _propertyKey_ on _obj_ creates a new data property named _propertyKey_ on _obj_. If _propertyKey_ refers to a non-writable data property on the [[Prototype]] object, set access of _propertyKey_ on _obj_ fails. If _propertyKey_ refers to an accessor property on the [[Prototype]] object, the accessor is inherited by _obj_ for both get access and set access.
Every ordinary object has a Boolean-valued [[Extensible]] internal slot which is used to fulfill the extensibility-related internal method invariants specified in
- In the following algorithm descriptions, assume _O_ is an ordinary object, _P_ is a property key value, _V_ is any ECMAScript language value, and _Desc_ is a Property Descriptor record.
- Each ordinary object internal method delegates to a similarly-named abstract operation. If such an abstract operation depends on another internal method, then the internal method is invoked on _O_ rather than calling the similarly-named abstract operation directly. These semantics ensure that exotic objects have their overridden internal methods invoked when ordinary object internal methods are applied to them.
+ In the following algorithm descriptions, assume _obj_ is an ordinary object, _propertyKey_ is a property key value, _value_ is any ECMAScript language value, and _propertyDesc_ is a Property Descriptor record.
+ Each ordinary object internal method delegates to a similarly-named abstract operation. If such an abstract operation depends on another internal method, then the internal method is invoked on _obj_ rather than calling the similarly-named abstract operation directly. These semantics ensure that exotic objects have their overridden internal methods invoked when ordinary object internal methods are applied to them.
[[GetPrototypeOf]] ( ): a normal completion containing either an Object or *null*
- for
- - an ordinary object _O_
+ - an ordinary object _obj_
- 1. Return OrdinaryGetPrototypeOf(_O_).
+ 1. Return OrdinaryGetPrototypeOf(_obj_).
OrdinaryGetPrototypeOf (
- _O_: an Object,
+ _obj_: an Object,
): an Object or *null*
- 1. Return _O_.[[Prototype]].
+ 1. Return _obj_.[[Prototype]].
@@ -12464,46 +13019,46 @@
[[SetPrototypeOf]] (
- _V_: an Object or *null*,
+ _proto_: an Object or *null*,
): a normal completion containing a Boolean
- for
- - an ordinary object _O_
+ - an ordinary object _obj_
- 1. Return OrdinarySetPrototypeOf(_O_, _V_).
+ 1. Return OrdinarySetPrototypeOf(_obj_, _proto_).
OrdinarySetPrototypeOf (
- _O_: an Object,
- _V_: an Object or *null*,
+ _obj_: an Object,
+ _proto_: an Object or *null*,
): a Boolean
- 1. Let _current_ be _O_.[[Prototype]].
- 1. If SameValue(_V_, _current_) is *true*, return *true*.
- 1. Let _extensible_ be _O_.[[Extensible]].
+ 1. Let _current_ be _obj_.[[Prototype]].
+ 1. If SameValue(_proto_, _current_) is *true*, return *true*.
+ 1. Let _extensible_ be _obj_.[[Extensible]].
1. If _extensible_ is *false*, return *false*.
- 1. Let _p_ be _V_.
+ 1. Let _cursor_ be _proto_.
1. Let _done_ be *false*.
1. [id="step-ordinarysetprototypeof-loop"] Repeat, while _done_ is *false*,
- 1. If _p_ is *null*, then
+ 1. If _cursor_ is *null*, then
1. Set _done_ to *true*.
- 1. Else if SameValue(_p_, _O_) is *true*, then
+ 1. Else if SameValue(_cursor_, _obj_) is *true*, then
1. Return *false*.
1. Else,
- 1. If _p_.[[GetPrototypeOf]] is not the ordinary object internal method defined in
- The loop in step
+ The loop in step
@@ -12512,22 +13067,22 @@
[[IsExtensible]] ( ): a normal completion containing a Boolean
- for
- - an ordinary object _O_
+ - an ordinary object _obj_
- 1. Return OrdinaryIsExtensible(_O_).
+ 1. Return OrdinaryIsExtensible(_obj_).
OrdinaryIsExtensible (
- _O_: an Object,
+ _obj_: an Object,
): a Boolean
- 1. Return _O_.[[Extensible]].
+ 1. Return _obj_.[[Extensible]].
@@ -12536,22 +13091,22 @@
[[PreventExtensions]] ( ): a normal completion containing *true*
- for
- - an ordinary object _O_
+ - an ordinary object _obj_
- 1. Return OrdinaryPreventExtensions(_O_).
+ 1. Return OrdinaryPreventExtensions(_obj_).
OrdinaryPreventExtensions (
- _O_: an Object,
+ _obj_: an Object,
): *true*
- 1. Set _O_.[[Extensible]] to *false*.
+ 1. Set _obj_.[[Extensible]] to *false*.
1. Return *true*.
@@ -12560,40 +13115,40 @@
[[GetOwnProperty]] (
- _P_: a property key,
+ _propertyKey_: a property key,
): a normal completion containing either a Property Descriptor or *undefined*
- for
- - an ordinary object _O_
+ - an ordinary object _obj_
- 1. Return OrdinaryGetOwnProperty(_O_, _P_).
+ 1. Return OrdinaryGetOwnProperty(_obj_, _propertyKey_).
OrdinaryGetOwnProperty (
- _O_: an Object,
- _P_: a property key,
+ _obj_: an Object,
+ _propertyKey_: a property key,
): a Property Descriptor or *undefined*
- 1. If _O_ does not have an own property with key _P_, return *undefined*.
- 1. Let _D_ be a newly created Property Descriptor with no fields.
- 1. Let _X_ be _O_'s own property whose key is _P_.
- 1. If _X_ is a data property, then
- 1. Set _D_.[[Value]] to the value of _X_'s [[Value]] attribute.
- 1. Set _D_.[[Writable]] to the value of _X_'s [[Writable]] attribute.
+ 1. If _obj_ does not have an own property with key _propertyKey_, return *undefined*.
+ 1. Let _propertyDesc_ be a newly created Property Descriptor with no fields.
+ 1. Let _ownProperty_ be _obj_'s own property whose key is _propertyKey_.
+ 1. If _ownProperty_ is a data property, then
+ 1. Set _propertyDesc_.[[Value]] to the value of _ownProperty_'s [[Value]] attribute.
+ 1. Set _propertyDesc_.[[Writable]] to the value of _ownProperty_'s [[Writable]] attribute.
1. Else,
- 1. Assert: _X_ is an accessor property.
- 1. Set _D_.[[Get]] to the value of _X_'s [[Get]] attribute.
- 1. Set _D_.[[Set]] to the value of _X_'s [[Set]] attribute.
- 1. Set _D_.[[Enumerable]] to the value of _X_'s [[Enumerable]] attribute.
- 1. Set _D_.[[Configurable]] to the value of _X_'s [[Configurable]] attribute.
- 1. Return _D_.
+ 1. Assert: _ownProperty_ is an accessor property.
+ 1. Set _propertyDesc_.[[Getter]] to the value of _ownProperty_'s [[Getter]] attribute.
+ 1. Set _propertyDesc_.[[Setter]] to the value of _ownProperty_'s [[Setter]] attribute.
+ 1. Set _propertyDesc_.[[Enumerable]] to the value of _ownProperty_'s [[Enumerable]] attribute.
+ 1. Set _propertyDesc_.[[Configurable]] to the value of _ownProperty_'s [[Configurable]] attribute.
+ 1. Return _propertyDesc_.
@@ -12601,97 +13156,98 @@
[[DefineOwnProperty]] (
- _P_: a property key,
- _Desc_: a Property Descriptor,
+ _propertyKey_: a property key,
+ _propertyDesc_: a Property Descriptor,
): either a normal completion containing a Boolean or a throw completion
- for
- - an ordinary object _O_
+ - an ordinary object _obj_
- 1. Return ? OrdinaryDefineOwnProperty(_O_, _P_, _Desc_).
+ 1. Return ? OrdinaryDefineOwnProperty(_obj_, _propertyKey_, _propertyDesc_).
OrdinaryDefineOwnProperty (
- _O_: an Object,
- _P_: a property key,
- _Desc_: a Property Descriptor,
+ _obj_: an Object,
+ _propertyKey_: a property key,
+ _propertyDesc_: a Property Descriptor,
): either a normal completion containing a Boolean or a throw completion
- 1. Let _current_ be ? _O_.[[GetOwnProperty]] (_P_).
- 1. Let _extensible_ be ? IsExtensible(_O_).
- 1. Return ValidateAndApplyPropertyDescriptor(_O_, _P_, _extensible_, _Desc_, _current_).
+ 1. Let _current_ be ? _obj_.[[GetOwnProperty]](_propertyKey_) .
+ 1. Let _extensible_ be ? IsExtensible(_obj_).
+ 1. Return ValidateAndApplyPropertyDescriptor(_obj_, _propertyKey_, _extensible_, _propertyDesc_, _current_).
IsCompatiblePropertyDescriptor (
- _Extensible_: a Boolean,
- _Desc_: a Property Descriptor,
- _Current_: a Property Descriptor or *undefined*,
+ _extensible_: a Boolean,
+ _propertyDesc_: a Property Descriptor,
+ _current_: a Property Descriptor or *undefined*,
): a Boolean
- 1. Return ValidateAndApplyPropertyDescriptor(*undefined*, *""*, _Extensible_, _Desc_, _Current_).
+ 1. Return ValidateAndApplyPropertyDescriptor(*undefined*, *""*, _extensible_, _propertyDesc_, _current_).
ValidateAndApplyPropertyDescriptor (
- _O_: an Object or *undefined*,
- _P_: a property key,
+ _obj_: an Object or *undefined*,
+ _propertyKey_: a property key,
_extensible_: a Boolean,
- _Desc_: a Property Descriptor,
+ _propertyDesc_: a Property Descriptor,
_current_: a Property Descriptor or *undefined*,
): a Boolean
- description
- - It returns *true* if and only if _Desc_ can be applied as the property of an object with specified _extensibility_ and current property _current_ while upholding
invariants . When such application is possible and _O_ is not *undefined*, it is performed for the property named _P_ (which is created if necessary).
+ - It returns *true* if and only if _propertyDesc_ can be applied as the property of an object with specified _extensibility_ and current property _current_ while upholding
invariants . When such application is possible and _obj_ is not *undefined*, it is performed for the property named _propertyKey_ (which is created if necessary).
- 1. Assert: _P_ is a property key.
+ 1. Assert: _propertyKey_ is a property key.
1. If _current_ is *undefined*, then
1. If _extensible_ is *false*, return *false*.
- 1. If _O_ is *undefined*, return *true*.
- 1. If IsAccessorDescriptor(_Desc_) is *true*, then
- 1. Create an own accessor property named _P_ of object _O_ whose [[Get]], [[Set]], [[Enumerable]], and [[Configurable]] attributes are set to the value of the corresponding field in _Desc_ if _Desc_ has that field, or to the attribute's default value otherwise.
+ 1. If _obj_ is *undefined*, return *true*.
+ 1. If IsAccessorDescriptor(_propertyDesc_) is *true*, then
+ 1. Create an own accessor property named _propertyKey_ of object _obj_ whose [[Getter]], [[Setter]], [[Enumerable]], and [[Configurable]] attributes are set to the value of the corresponding field in _propertyDesc_ if _propertyDesc_ has that field, or to the attribute's default value otherwise.
1. Else,
- 1. Create an own data property named _P_ of object _O_ whose [[Value]], [[Writable]], [[Enumerable]], and [[Configurable]] attributes are set to the value of the corresponding field in _Desc_ if _Desc_ has that field, or to the attribute's default value otherwise.
+ 1. Create an own data property named _propertyKey_ of object _obj_ whose [[Value]], [[Writable]], [[Enumerable]], and [[Configurable]] attributes are set to the value of the corresponding field in _propertyDesc_ if _propertyDesc_ has that field, or to the attribute's default value otherwise.
1. Return *true*.
1. Assert: _current_ is a fully populated Property Descriptor.
- 1. If _Desc_ does not have any fields, return *true*.
+ 1. If _propertyDesc_ does not have any fields, return *true*.
1. If _current_.[[Configurable]] is *false*, then
- 1. If _Desc_ has a [[Configurable]] field and _Desc_.[[Configurable]] is *true*, return *false*.
- 1. If _Desc_ has an [[Enumerable]] field and _Desc_.[[Enumerable]] is not _current_.[[Enumerable]], return *false*.
- 1. If IsGenericDescriptor(_Desc_) is *false* and IsAccessorDescriptor(_Desc_) is not IsAccessorDescriptor(_current_), return *false*.
+ 1. If _propertyDesc_ has a [[Configurable]] field and _propertyDesc_.[[Configurable]] is *true*, return *false*.
+ 1. If _propertyDesc_ has an [[Enumerable]] field and _propertyDesc_.[[Enumerable]] is not _current_.[[Enumerable]], return *false*.
+ 1. If IsGenericDescriptor(_propertyDesc_) is *false* and IsAccessorDescriptor(_propertyDesc_) is not IsAccessorDescriptor(_current_), return *false*.
1. If IsAccessorDescriptor(_current_) is *true*, then
- 1. If _Desc_ has a [[Get]] field and SameValue(_Desc_.[[Get]], _current_.[[Get]]) is *false*, return *false*.
- 1. If _Desc_ has a [[Set]] field and SameValue(_Desc_.[[Set]], _current_.[[Set]]) is *false*, return *false*.
+ 1. If _propertyDesc_ has a [[Getter]] field and SameValue(_propertyDesc_.[[Getter]], _current_.[[Getter]]) is *false*, return *false*.
+ 1. If _propertyDesc_ has a [[Setter]] field and SameValue(_propertyDesc_.[[Setter]], _current_.[[Setter]]) is *false*, return *false*.
1. Else if _current_.[[Writable]] is *false*, then
- 1. If _Desc_ has a [[Writable]] field and _Desc_.[[Writable]] is *true*, return *false*.
- 1. If _Desc_ has a [[Value]] field and SameValue(_Desc_.[[Value]], _current_.[[Value]]) is *false*, return *false*.
- 1. If _O_ is not *undefined*, then
- 1. If IsDataDescriptor(_current_) is *true* and IsAccessorDescriptor(_Desc_) is *true*, then
- 1. If _Desc_ has a [[Configurable]] field, let _configurable_ be _Desc_.[[Configurable]]; else let _configurable_ be _current_.[[Configurable]].
- 1. If _Desc_ has a [[Enumerable]] field, let _enumerable_ be _Desc_.[[Enumerable]]; else let _enumerable_ be _current_.[[Enumerable]].
- 1. Replace the property named _P_ of object _O_ with an accessor property whose [[Configurable]] and [[Enumerable]] attributes are set to _configurable_ and _enumerable_, respectively, and whose [[Get]] and [[Set]] attributes are set to the value of the corresponding field in _Desc_ if _Desc_ has that field, or to the attribute's default value otherwise.
- 1. Else if IsAccessorDescriptor(_current_) is *true* and IsDataDescriptor(_Desc_) is *true*, then
- 1. If _Desc_ has a [[Configurable]] field, let _configurable_ be _Desc_.[[Configurable]]; else let _configurable_ be _current_.[[Configurable]].
- 1. If _Desc_ has a [[Enumerable]] field, let _enumerable_ be _Desc_.[[Enumerable]]; else let _enumerable_ be _current_.[[Enumerable]].
- 1. Replace the property named _P_ of object _O_ with a data property whose [[Configurable]] and [[Enumerable]] attributes are set to _configurable_ and _enumerable_, respectively, and whose [[Value]] and [[Writable]] attributes are set to the value of the corresponding field in _Desc_ if _Desc_ has that field, or to the attribute's default value otherwise.
+ 1. If _propertyDesc_ has a [[Writable]] field and _propertyDesc_.[[Writable]] is *true*, return *false*.
+ 1. NOTE: SameValue returns *true* for *NaN* values which may be distinguishable by other means. Returning here ensures that any existing property of _obj_ remains unmodified.
+ 1. If _propertyDesc_ has a [[Value]] field, return SameValue(_propertyDesc_.[[Value]], _current_.[[Value]]).
+ 1. If _obj_ is not *undefined*, then
+ 1. If IsDataDescriptor(_current_) is *true* and IsAccessorDescriptor(_propertyDesc_) is *true*, then
+ 1. If _propertyDesc_ has a [[Configurable]] field, let _configurable_ be _propertyDesc_.[[Configurable]]; else let _configurable_ be _current_.[[Configurable]].
+ 1. If _propertyDesc_ has an [[Enumerable]] field, let _enumerable_ be _propertyDesc_.[[Enumerable]]; else let _enumerable_ be _current_.[[Enumerable]].
+ 1. Replace the property named _propertyKey_ of object _obj_ with an accessor property whose [[Configurable]] and [[Enumerable]] attributes are set to _configurable_ and _enumerable_, respectively, and whose [[Getter]] and [[Setter]] attributes are set to the value of the corresponding field in _propertyDesc_ if _propertyDesc_ has that field, or to the attribute's default value otherwise.
+ 1. Else if IsAccessorDescriptor(_current_) is *true* and IsDataDescriptor(_propertyDesc_) is *true*, then
+ 1. If _propertyDesc_ has a [[Configurable]] field, let _configurable_ be _propertyDesc_.[[Configurable]]; else let _configurable_ be _current_.[[Configurable]].
+ 1. If _propertyDesc_ has an [[Enumerable]] field, let _enumerable_ be _propertyDesc_.[[Enumerable]]; else let _enumerable_ be _current_.[[Enumerable]].
+ 1. Replace the property named _propertyKey_ of object _obj_ with a data property whose [[Configurable]] and [[Enumerable]] attributes are set to _configurable_ and _enumerable_, respectively, and whose [[Value]] and [[Writable]] attributes are set to the value of the corresponding field in _propertyDesc_ if _propertyDesc_ has that field, or to the attribute's default value otherwise.
1. Else,
- 1. For each field of _Desc_, set the corresponding attribute of the property named _P_ of object _O_ to the value of the field.
+ 1. For each field name _fieldName_ of _propertyDesc_, set the attribute named _fieldName_ of the property named _propertyKey_ of object _obj_ to the value of _propertyDesc_'s _fieldName_ field.
1. Return *true*.
@@ -12700,32 +13256,32 @@
[[HasProperty]] (
- _P_: a property key,
+ _propertyKey_: a property key,
): either a normal completion containing a Boolean or a throw completion
- for
- - an ordinary object _O_
+ - an ordinary object _obj_
- 1. Return ? OrdinaryHasProperty(_O_, _P_).
+ 1. Return ? OrdinaryHasProperty(_obj_, _propertyKey_).
OrdinaryHasProperty (
- _O_: an Object,
- _P_: a property key,
+ _obj_: an Object,
+ _propertyKey_: a property key,
): either a normal completion containing a Boolean or a throw completion
- 1. Let _hasOwn_ be ? _O_.[[GetOwnProperty]] (_P_).
+ 1. Let _hasOwn_ be ? _obj_.[[GetOwnProperty]](_propertyKey_) .
1. If _hasOwn_ is not *undefined*, return *true*.
- 1. Let _parent_ be ? _O_.[[GetPrototypeOf]] ().
+ 1. Let _parent_ be ? _obj_.[[GetPrototypeOf]]() .
1. If _parent_ is not *null*, then
- 1. Return ? _parent_.[[HasProperty]] (_P_).
+ 1. Return ? _parent_.[[HasProperty]](_propertyKey_) .
1. Return *false*.
@@ -12734,41 +13290,41 @@
[[Get]] (
- _P_: a property key,
- _Receiver_: an ECMAScript language value,
+ _propertyKey_: a property key,
+ _receiver_: an ECMAScript language value,
): either a normal completion containing an ECMAScript language value or a throw completion
- for
- - an ordinary object _O_
+ - an ordinary object _obj_
- 1. Return ? OrdinaryGet(_O_, _P_, _Receiver_).
+ 1. Return ? OrdinaryGet(_obj_, _propertyKey_, _receiver_).
OrdinaryGet (
- _O_: an Object,
- _P_: a property key,
- _Receiver_: an ECMAScript language value,
+ _obj_: an Object,
+ _propertyKey_: a property key,
+ _receiver_: an ECMAScript language value,
): either a normal completion containing an ECMAScript language value or a throw completion
- 1. Let _desc_ be ? _O_.[[GetOwnProperty]] (_P_).
- 1. If _desc_ is *undefined*, then
- 1. Let _parent_ be ? _O_.[[GetPrototypeOf]] ().
+ 1. Let _propertyDesc_ be ? _obj_.[[GetOwnProperty]](_propertyKey_) .
+ 1. If _propertyDesc_ is *undefined*, then
+ 1. Let _parent_ be ? _obj_.[[GetPrototypeOf]]() .
1. If _parent_ is *null*, return *undefined*.
- 1. Return ? _parent_.[[Get]] (_P_, _Receiver_).
- 1. If IsDataDescriptor(_desc_) is *true*, return _desc_.[[Value]].
- 1. Assert: IsAccessorDescriptor(_desc_) is *true*.
- 1. Let _getter_ be _desc_.[[Get]].
+ 1. Return ? _parent_.[[Get]](_propertyKey_, _receiver_) .
+ 1. If IsDataDescriptor(_propertyDesc_) is *true*, return _propertyDesc_.[[Value]].
+ 1. Assert: IsAccessorDescriptor(_propertyDesc_) is *true*.
+ 1. Let _getter_ be _propertyDesc_.[[Getter]].
1. If _getter_ is *undefined*, return *undefined*.
- 1. Return ? Call(_getter_, _Receiver_).
+ 1. Return ? Call(_getter_, _receiver_).
@@ -12776,44 +13332,44 @@
[[Set]] (
- _P_: a property key,
- _V_: an ECMAScript language value,
- _Receiver_: an ECMAScript language value,
+ _propertyKey_: a property key,
+ _value_: an ECMAScript language value,
+ _receiver_: an ECMAScript language value,
): either a normal completion containing a Boolean or a throw completion
- for
- - an ordinary object _O_
+ - an ordinary object _obj_
- 1. Return ? OrdinarySet(_O_, _P_, _V_, _Receiver_).
+ 1. Return ? OrdinarySet(_obj_, _propertyKey_, _value_, _receiver_).
OrdinarySet (
- _O_: an Object,
- _P_: a property key,
- _V_: an ECMAScript language value,
- _Receiver_: an ECMAScript language value,
+ _obj_: an Object,
+ _propertyKey_: a property key,
+ _value_: an ECMAScript language value,
+ _receiver_: an ECMAScript language value,
): either a normal completion containing a Boolean or a throw completion
- 1. Let _ownDesc_ be ? _O_.[[GetOwnProperty]] (_P_).
- 1. Return ? OrdinarySetWithOwnDescriptor(_O_, _P_, _V_, _Receiver_, _ownDesc_).
+ 1. Let _ownDesc_ be ? _obj_.[[GetOwnProperty]](_propertyKey_) .
+ 1. Return ? OrdinarySetWithOwnDescriptor(_obj_, _propertyKey_, _value_, _receiver_, _ownDesc_).
OrdinarySetWithOwnDescriptor (
- _O_: an Object,
- _P_: a property key,
- _V_: an ECMAScript language value,
- _Receiver_: an ECMAScript language value,
+ _obj_: an Object,
+ _propertyKey_: a property key,
+ _value_: an ECMAScript language value,
+ _receiver_: an ECMAScript language value,
_ownDesc_: a Property Descriptor or *undefined*,
): either a normal completion containing a Boolean or a throw completion
@@ -12822,27 +13378,24 @@
1. If _ownDesc_ is *undefined*, then
- 1. Let _parent_ be ? _O_.[[GetPrototypeOf]] ().
- 1. If _parent_ is not *null*, then
- 1. Return ? _parent_.[[Set]] (_P_, _V_, _Receiver_).
- 1. Else,
- 1. Set _ownDesc_ to the PropertyDescriptor { [[Value]]: *undefined*, [[Writable]]: *true*, [[Enumerable]]: *true*, [[Configurable]]: *true* }.
+ 1. Let _parent_ be ? _obj_.[[GetPrototypeOf]]() .
+ 1. If _parent_ is not *null*, return ? _parent_.[[Set]](_propertyKey_, _value_, _receiver_) .
+ 1. Set _ownDesc_ to the PropertyDescriptor { [[Value]]: *undefined*, [[Writable]]: *true*, [[Enumerable]]: *true*, [[Configurable]]: *true* }.
1. If IsDataDescriptor(_ownDesc_) is *true*, then
1. If _ownDesc_.[[Writable]] is *false*, return *false*.
- 1. If _Receiver_ is not an Object, return *false*.
- 1. Let _existingDescriptor_ be ? _Receiver_.[[GetOwnProperty]] (_P_).
- 1. If _existingDescriptor_ is not *undefined*, then
- 1. If IsAccessorDescriptor(_existingDescriptor_) is *true*, return *false*.
- 1. If _existingDescriptor_.[[Writable]] is *false*, return *false*.
- 1. Let _valueDesc_ be the PropertyDescriptor { [[Value]]: _V_ }.
- 1. Return ? _Receiver_.[[DefineOwnProperty]] (_P_, _valueDesc_).
- 1. Else,
- 1. Assert: _Receiver_ does not currently have a property _P_.
- 1. Return ? CreateDataProperty(_Receiver_, _P_, _V_).
+ 1. If _receiver_ is not an Object, return *false*.
+ 1. Let _existingDesc_ be ? _receiver_.[[GetOwnProperty]](_propertyKey_) .
+ 1. If _existingDesc_ is *undefined*, then
+ 1. Assert: _receiver_ does not currently have a property _propertyKey_.
+ 1. Return ? CreateDataProperty(_receiver_, _propertyKey_, _value_).
+ 1. If IsAccessorDescriptor(_existingDesc_) is *true*, return *false*.
+ 1. If _existingDesc_.[[Writable]] is *false*, return *false*.
+ 1. Let _valueDesc_ be the PropertyDescriptor { [[Value]]: _value_ }.
+ 1. Return ? _receiver_.[[DefineOwnProperty]](_propertyKey_, _valueDesc_) .
1. Assert: IsAccessorDescriptor(_ownDesc_) is *true*.
- 1. Let _setter_ be _ownDesc_.[[Set]].
+ 1. Let _setter_ be _ownDesc_.[[Setter]].
1. If _setter_ is *undefined*, return *false*.
- 1. Perform ? Call(_setter_, _Receiver_, « _V_ »).
+ 1. Perform ? Call(_setter_, _receiver_, « _value_ »).
1. Return *true*.
@@ -12851,31 +13404,31 @@
[[Delete]] (
- _P_: a property key,
+ _propertyKey_: a property key,
): either a normal completion containing a Boolean or a throw completion
- for
- - an ordinary object _O_
+ - an ordinary object _obj_
- 1. Return ? OrdinaryDelete(_O_, _P_).
+ 1. Return ? OrdinaryDelete(_obj_, _propertyKey_).
OrdinaryDelete (
- _O_: an Object,
- _P_: a property key,
+ _obj_: an Object,
+ _propertyKey_: a property key,
): either a normal completion containing a Boolean or a throw completion
- 1. Let _desc_ be ? _O_.[[GetOwnProperty]] (_P_).
- 1. If _desc_ is *undefined*, return *true*.
- 1. If _desc_.[[Configurable]] is *true*, then
- 1. Remove the own property with name _P_ from _O_.
+ 1. Let _propertyDesc_ be ? _obj_.[[GetOwnProperty]](_propertyKey_) .
+ 1. If _propertyDesc_ is *undefined*, return *true*.
+ 1. If _propertyDesc_.[[Configurable]] is *true*, then
+ 1. Remove the own property with name _propertyKey_ from _obj_.
1. Return *true*.
1. Return *false*.
@@ -12886,16 +13439,16 @@
[[OwnPropertyKeys]] ( ): a normal completion containing a List of property keys
- for
- - an ordinary object _O_
+ - an ordinary object _obj_
- 1. Return OrdinaryOwnPropertyKeys(_O_).
+ 1. Return OrdinaryOwnPropertyKeys(_obj_).
OrdinaryOwnPropertyKeys (
- _O_: an Object,
+ _obj_: an Object,
): a List of property keys
@@ -12903,12 +13456,12 @@
1. Let _keys_ be a new empty List.
- 1. For each own property key _P_ of _O_ such that _P_ is an array index, in ascending numeric index order, do
- 1. Append _P_ to _keys_.
- 1. For each own property key _P_ of _O_ such that _P_ is a String and _P_ is not an array index, in ascending chronological order of property creation, do
- 1. Append _P_ to _keys_.
- 1. For each own property key _P_ of _O_ such that _P_ is a Symbol, in ascending chronological order of property creation, do
- 1. Append _P_ to _keys_.
+ 1. For each own property key _propertyKey_ of _obj_ such that _propertyKey_ is an array index, in ascending numeric index order, do
+ 1. Append _propertyKey_ to _keys_.
+ 1. For each own property key _propertyKey_ of _obj_ such that _propertyKey_ is a String and _propertyKey_ is not an array index, in ascending chronological order of property creation, do
+ 1. Append _propertyKey_ to _keys_.
+ 1. For each own property key _propertyKey_ of _obj_ such that _propertyKey_ is a Symbol, in ascending chronological order of property creation, do
+ 1. Append _propertyKey_ to _keys_.
1. Return _keys_.
@@ -12928,9 +13481,9 @@
1. Let _internalSlotsList_ be « [[Prototype]], [[Extensible]] ».
1. If _additionalInternalSlotsList_ is present, set _internalSlotsList_ to the list-concatenation of _internalSlotsList_ and _additionalInternalSlotsList_.
- 1. Let _O_ be MakeBasicObject(_internalSlotsList_).
- 1. Set _O_.[[Prototype]] to _proto_.
- 1. Return _O_.
+ 1. Let _obj_ be MakeBasicObject(_internalSlotsList_).
+ 1. Set _obj_.[[Prototype]] to _proto_.
+ 1. Return _obj_.
@@ -12941,7 +13494,7 @@
OrdinaryCreateFromConstructor (
- _constructor_: a constructor,
+ _ctor_: a function object,
_intrinsicDefaultProto_: a String,
optional _internalSlotsList_: a List of names of internal slots,
): either a normal completion containing an Object or a throw completion
@@ -12952,17 +13505,17 @@
1. Assert: _intrinsicDefaultProto_ is this specification's name of an intrinsic object. The corresponding object must be an intrinsic that is intended to be used as the [[Prototype]] value of an object.
- 1. Let _proto_ be ? GetPrototypeFromConstructor(_constructor_, _intrinsicDefaultProto_).
- 1. If _internalSlotsList_ is present, let _slotsList_ be _internalSlotsList_.
- 1. Else, let _slotsList_ be a new empty List.
- 1. Return OrdinaryObjectCreate(_proto_, _slotsList_).
+ 1. Let _proto_ be ? GetPrototypeFromConstructor(_ctor_, _intrinsicDefaultProto_).
+ 1. If _internalSlotsList_ is present, let _slots_ be _internalSlotsList_.
+ 1. Else, let _slots_ be a new empty List.
+ 1. Return OrdinaryObjectCreate(_proto_, _slots_).
GetPrototypeFromConstructor (
- _constructor_: a function object,
+ _ctor_: a function object,
_intrinsicDefaultProto_: a String,
): either a normal completion containing an Object or a throw completion
@@ -12972,31 +13525,31 @@
1. Assert: _intrinsicDefaultProto_ is this specification's name of an intrinsic object. The corresponding object must be an intrinsic that is intended to be used as the [[Prototype]] value of an object.
- 1. Let _proto_ be ? Get(_constructor_, *"prototype"*).
+ 1. Let _proto_ be ? Get(_ctor_, *"prototype"*).
1. If _proto_ is not an Object, then
- 1. Let _realm_ be ? GetFunctionRealm(_constructor_).
+ 1. Let _realm_ be ? GetFunctionRealm(_ctor_).
1. Set _proto_ to _realm_'s intrinsic object named _intrinsicDefaultProto_.
1. Return _proto_.
- If _constructor_ does not supply a [[Prototype]] value, the default value that is used is obtained from the realm of the _constructor_ function rather than from the running execution context.
+ If _ctor_ does not supply a [[Prototype]] value, the default value that is used is obtained from the realm of the _ctor_ function rather than from the running execution context.
RequireInternalSlot (
- _O_: an ECMAScript language value,
+ _obj_: an ECMAScript language value,
_internalSlot_: an internal slot name,
): either a normal completion containing ~unused~ or a throw completion
- description
- - It throws an exception unless _O_ is an Object and has the given internal slot.
+ - It throws an exception unless _obj_ is an Object and has the given internal slot.
- 1. If _O_ is not an Object, throw a *TypeError* exception.
- 1. If _O_ does not have an _internalSlot_ internal slot, throw a *TypeError* exception.
+ 1. If _obj_ is not an Object, throw a *TypeError* exception.
+ 1. If _obj_ does not have an _internalSlot_ internal slot, throw a *TypeError* exception.
1. Return ~unused~.
@@ -13008,17 +13561,19 @@ ECMAScript Function Objects
In addition to [[Extensible]] and [[Prototype]], ECMAScript function objects also have the internal slots listed in
-
-
- Internal Slot
-
-
- Type
-
-
- Description
-
-
+
+
+
+ Internal Slot
+
+
+ Type
+
+
+ Description
+
+
+
[[Environment]]
@@ -13123,7 +13678,7 @@ ECMAScript Function Objects
[[HomeObject]]
- an Object
+ an Object or *undefined*
If the function uses `super`, this is the object whose [[GetPrototypeOf]] provides the object where `super` property lookups begin.
@@ -13191,29 +13746,29 @@ ECMAScript Function Objects
[[Call]] (
- _thisArgument_: an ECMAScript language value,
- _argumentsList_: a List of ECMAScript language values,
+ _thisArg_: an ECMAScript language value,
+ _argList_: a List of ECMAScript language values,
): either a normal completion containing an ECMAScript language value or a throw completion
- for
- - an ECMAScript function object _F_
+ - an ECMAScript function object _func_
1. Let _callerContext_ be the running execution context.
- 1. Let _calleeContext_ be PrepareForOrdinaryCall(_F_, *undefined*).
+ 1. Let _calleeContext_ be PrepareForOrdinaryCall(_func_, *undefined*).
1. Assert: _calleeContext_ is now the running execution context.
- 1. If _F_.[[IsClassConstructor]] is *true*, then
+ 1. If _func_.[[IsClassConstructor]] is *true*, then
1. Let _error_ be a newly created *TypeError* object.
- 1. NOTE: _error_ is created in _calleeContext_ with _F_'s associated Realm Record.
+ 1. NOTE: _error_ is created in _calleeContext_ with _func_'s associated Realm Record.
1. Remove _calleeContext_ from the execution context stack and restore _callerContext_ as the running execution context.
- 1. Return ThrowCompletion(_error_).
- 1. Perform OrdinaryCallBindThis(_F_, _calleeContext_, _thisArgument_).
- 1. Let _result_ be Completion(OrdinaryCallEvaluateBody(_F_, _argumentsList_)).
+ 1. Throw _error_.
+ 1. Perform OrdinaryCallBindThis(_func_, _calleeContext_, _thisArg_).
+ 1. Let _result_ be Completion(OrdinaryCallEvaluateBody(_func_, _argList_)).
1. [id="step-call-pop-context-stack"] Remove _calleeContext_ from the execution context stack and restore _callerContext_ as the running execution context.
1. If _result_ is a return completion, return _result_.[[Value]].
- 1. ReturnIfAbrupt(_result_).
- 1. Return *undefined*.
+ 1. Assert: _result_ is a throw completion.
+ 1. Return ? _result_.
When _calleeContext_ is removed from the execution context stack in step
@@ -13222,7 +13777,7 @@
PrepareForOrdinaryCall (
- _F_: an ECMAScript function object,
+ _func_: an ECMAScript function object,
_newTarget_: an Object or *undefined*,
): an execution context
@@ -13231,14 +13786,14 @@
1. Let _callerContext_ be the running execution context.
1. Let _calleeContext_ be a new ECMAScript code execution context.
- 1. Set the Function of _calleeContext_ to _F_.
- 1. Let _calleeRealm_ be _F_.[[Realm]].
+ 1. Set the Function of _calleeContext_ to _func_.
+ 1. Let _calleeRealm_ be _func_.[[Realm]].
1. Set the Realm of _calleeContext_ to _calleeRealm_.
- 1. Set the ScriptOrModule of _calleeContext_ to _F_.[[ScriptOrModule]].
- 1. Let _localEnv_ be NewFunctionEnvironment(_F_, _newTarget_).
+ 1. Set the ScriptOrModule of _calleeContext_ to _func_.[[ScriptOrModule]].
+ 1. Let _localEnv_ be NewFunctionEnvironment(_func_, _newTarget_).
1. Set the LexicalEnvironment of _calleeContext_ to _localEnv_.
1. Set the VariableEnvironment of _calleeContext_ to _localEnv_.
- 1. Set the PrivateEnvironment of _calleeContext_ to _F_.[[PrivateEnvironment]].
+ 1. Set the PrivateEnvironment of _calleeContext_ to _func_.[[PrivateEnvironment]].
1. If _callerContext_ is not already suspended, suspend _callerContext_.
1. Push _calleeContext_ onto the execution context stack; _calleeContext_ is now the running execution context.
1. NOTE: Any exception objects produced after this point are associated with _calleeRealm_.
@@ -13249,31 +13804,31 @@
OrdinaryCallBindThis (
- _F_: an ECMAScript function object,
+ _func_: an ECMAScript function object,
_calleeContext_: an execution context,
- _thisArgument_: an ECMAScript language value,
+ _thisArg_: an ECMAScript language value,
): ~unused~
- 1. Let _thisMode_ be _F_.[[ThisMode]].
+ 1. Let _thisMode_ be _func_.[[ThisMode]].
1. If _thisMode_ is ~lexical~, return ~unused~.
- 1. Let _calleeRealm_ be _F_.[[Realm]].
+ 1. Let _calleeRealm_ be _func_.[[Realm]].
1. Let _localEnv_ be the LexicalEnvironment of _calleeContext_.
1. If _thisMode_ is ~strict~, then
- 1. Let _thisValue_ be _thisArgument_.
+ 1. Let _thisValue_ be _thisArg_.
1. Else,
- 1. If _thisArgument_ is either *undefined* or *null*, then
+ 1. If _thisArg_ is either *undefined* or *null*, then
1. Let _globalEnv_ be _calleeRealm_.[[GlobalEnv]].
1. Assert: _globalEnv_ is a Global Environment Record.
1. Let _thisValue_ be _globalEnv_.[[GlobalThisValue]].
1. Else,
- 1. Let _thisValue_ be ! ToObject(_thisArgument_).
+ 1. Let _thisValue_ be ! ToObject(_thisArg_).
1. NOTE: ToObject produces wrapper objects using _calleeRealm_.
1. Assert: _localEnv_ is a Function Environment Record.
1. Assert: The next step never returns an abrupt completion because _localEnv_.[[ThisBindingStatus]] is not ~initialized~.
- 1. Perform ! _localEnv_.BindThisValue(_thisValue_).
+ 1. Perform ! BindThisValue(_localEnv_, _thisValue_).
1. Return ~unused~.
@@ -13281,55 +13836,55 @@
Runtime Semantics: EvaluateBody (
- _functionObject_: an ECMAScript function object,
- _argumentsList_: a List of ECMAScript language values,
- ): either a normal completion containing an ECMAScript language value or an abrupt completion
+ _func_: an ECMAScript function object,
+ _argList_: a List of ECMAScript language values,
+ ): a return completion or a throw completion
FunctionBody : FunctionStatementList
- 1. Return ? EvaluateFunctionBody of |FunctionBody| with arguments _functionObject_ and _argumentsList_.
+ 1. Return ? EvaluateFunctionBody of |FunctionBody| with arguments _func_ and _argList_.
ConciseBody : ExpressionBody
- 1. Return ? EvaluateConciseBody of |ConciseBody| with arguments _functionObject_ and _argumentsList_.
+ 1. Return ? EvaluateConciseBody of |ConciseBody| with arguments _func_ and _argList_.
GeneratorBody : FunctionBody
- 1. Return ? EvaluateGeneratorBody of |GeneratorBody| with arguments _functionObject_ and _argumentsList_.
+ 1. Return ? EvaluateGeneratorBody of |GeneratorBody| with arguments _func_ and _argList_.
AsyncGeneratorBody : FunctionBody
- 1. Return ? EvaluateAsyncGeneratorBody of |AsyncGeneratorBody| with arguments _functionObject_ and _argumentsList_.
+ 1. Return ? EvaluateAsyncGeneratorBody of |AsyncGeneratorBody| with arguments _func_ and _argList_.
AsyncFunctionBody : FunctionBody
- 1. Return ? EvaluateAsyncFunctionBody of |AsyncFunctionBody| with arguments _functionObject_ and _argumentsList_.
+ 1. Return ? EvaluateAsyncFunctionBody of |AsyncFunctionBody| with arguments _func_ and _argList_.
AsyncConciseBody : ExpressionBody
- 1. Return ? EvaluateAsyncConciseBody of |AsyncConciseBody| with arguments _functionObject_ and _argumentsList_.
+ 1. Return ? EvaluateAsyncConciseBody of |AsyncConciseBody| with arguments _func_ and _argList_.
Initializer :
`=` AssignmentExpression
- 1. Assert: _argumentsList_ is empty.
- 1. Assert: _functionObject_.[[ClassFieldInitializerName]] is not ~empty~.
+ 1. Assert: _argList_ is empty.
+ 1. Assert: _func_.[[ClassFieldInitializerName]] is not ~empty~.
1. If IsAnonymousFunctionDefinition(|AssignmentExpression|) is *true*, then
- 1. Let _value_ be ? NamedEvaluation of |Initializer| with argument _functionObject_.[[ClassFieldInitializerName]].
+ 1. Let _value_ be ? NamedEvaluation of |Initializer| with argument _func_.[[ClassFieldInitializerName]].
1. Else,
1. Let _rhs_ be ? Evaluation of |AssignmentExpression|.
1. Let _value_ be ? GetValue(_rhs_).
- 1. Return Completion Record { [[Type]]: ~return~, [[Value]]: _value_, [[Target]]: ~empty~ }.
+ 1. Return ReturnCompletion(_value_).
Even though field initializers constitute a function boundary, calling FunctionDeclarationInstantiation does not have any observable effect and so is omitted.
@@ -13338,22 +13893,22 @@
ClassStaticBlockBody : ClassStaticBlockStatementList
- 1. Assert: _argumentsList_ is empty.
- 1. Return ? EvaluateClassStaticBlockBody of |ClassStaticBlockBody| with argument _functionObject_.
+ 1. Assert: _argList_ is empty.
+ 1. Return ? EvaluateClassStaticBlockBody of |ClassStaticBlockBody| with argument _func_.
OrdinaryCallEvaluateBody (
- _F_: an ECMAScript function object,
- _argumentsList_: a List of ECMAScript language values,
- ): either a normal completion containing an ECMAScript language value or an abrupt completion
+ _func_: an ECMAScript function object,
+ _argList_: a List of ECMAScript language values,
+ ): a return completion or a throw completion
- 1. Return ? EvaluateBody of _F_.[[ECMAScriptCode]] with arguments _F_ and _argumentsList_.
+ 1. Return ? EvaluateBody of _func_.[[ECMAScriptCode]] with arguments _func_ and _argList_.
@@ -13361,37 +13916,37 @@
[[Construct]] (
- _argumentsList_: a List of ECMAScript language values,
+ _argList_: a List of ECMAScript language values,
_newTarget_: a constructor,
): either a normal completion containing an Object or a throw completion
- for
- - an ECMAScript function object _F_
+ - an ECMAScript function object _func_
1. Let _callerContext_ be the running execution context.
- 1. Let _kind_ be _F_.[[ConstructorKind]].
+ 1. Let _kind_ be _func_.[[ConstructorKind]].
1. If _kind_ is ~base~, then
- 1. Let _thisArgument_ be ? OrdinaryCreateFromConstructor(_newTarget_, *"%Object.prototype%"*).
- 1. Let _calleeContext_ be PrepareForOrdinaryCall(_F_, _newTarget_).
+ 1. Let _thisArg_ be ? OrdinaryCreateFromConstructor(_newTarget_, *"%Object.prototype%"*).
+ 1. Let _calleeContext_ be PrepareForOrdinaryCall(_func_, _newTarget_).
1. Assert: _calleeContext_ is now the running execution context.
1. If _kind_ is ~base~, then
- 1. Perform OrdinaryCallBindThis(_F_, _calleeContext_, _thisArgument_).
- 1. Let _initializeResult_ be Completion(InitializeInstanceElements(_thisArgument_, _F_)).
+ 1. Perform OrdinaryCallBindThis(_func_, _calleeContext_, _thisArg_).
+ 1. Let _initializeResult_ be Completion(InitializeInstanceElements(_thisArg_, _func_)).
1. If _initializeResult_ is an abrupt completion, then
1. Remove _calleeContext_ from the execution context stack and restore _callerContext_ as the running execution context.
1. Return ? _initializeResult_.
- 1. Let _constructorEnv_ be the LexicalEnvironment of _calleeContext_.
- 1. Let _result_ be Completion(OrdinaryCallEvaluateBody(_F_, _argumentsList_)).
+ 1. Let _ctorEnv_ be the LexicalEnvironment of _calleeContext_.
+ 1. Let _result_ be Completion(OrdinaryCallEvaluateBody(_func_, _argList_)).
1. Remove _calleeContext_ from the execution context stack and restore _callerContext_ as the running execution context.
- 1. If _result_ is a return completion, then
- 1. If _result_.[[Value]] is an Object, return _result_.[[Value]].
- 1. If _kind_ is ~base~, return _thisArgument_.
- 1. If _result_.[[Value]] is not *undefined*, throw a *TypeError* exception.
- 1. Else,
- 1. ReturnIfAbrupt(_result_).
- 1. Let _thisBinding_ be ? _constructorEnv_.GetThisBinding().
+ 1. If _result_ is a throw completion, then
+ 1. Return ? _result_.
+ 1. Assert: _result_ is a return completion.
+ 1. If _result_.[[Value]] is an Object, return _result_.[[Value]].
+ 1. If _kind_ is ~base~, return _thisArg_.
+ 1. If _result_.[[Value]] is not *undefined*, throw a *TypeError* exception.
+ 1. Let _thisBinding_ be ? _ctorEnv_.GetThisBinding().
1. Assert: _thisBinding_ is an Object.
1. Return _thisBinding_.
@@ -13400,12 +13955,12 @@
OrdinaryFunctionCreate (
- _functionPrototype_: an Object,
+ _proto_: an Object,
_sourceText_: a sequence of Unicode code points,
- _ParameterList_: a Parse Node,
- _Body_: a Parse Node,
+ _paramList_: a Parse Node,
+ _body_: a Parse Node,
_thisMode_: ~lexical-this~ or ~non-lexical-this~,
- _env_: an Environment Record,
+ _envRecord_: an Environment Record,
_privateEnv_: a PrivateEnvironment Record or *null*,
): an ECMAScript function object
@@ -13415,35 +13970,35 @@
1. Let _internalSlotsList_ be the internal slots listed in
AddRestrictedFunctionProperties (
- _F_: a function object,
+ _func_: a function object,
_realm_: a Realm Record,
): ~unused~
@@ -13452,12 +14007,12 @@
1. Assert: _realm_.[[Intrinsics]].[[%ThrowTypeError%]] exists and has been initialized.
1. Let _thrower_ be _realm_.[[Intrinsics]].[[%ThrowTypeError%]].
- 1. Perform ! DefinePropertyOrThrow(_F_, *"caller"*, PropertyDescriptor { [[Get]]: _thrower_, [[Set]]: _thrower_, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
- 1. Perform ! DefinePropertyOrThrow(_F_, *"arguments"*, PropertyDescriptor { [[Get]]: _thrower_, [[Set]]: _thrower_, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
+ 1. Perform ! DefinePropertyOrThrow(_func_, *"caller"*, PropertyDescriptor { [[Getter]]: _thrower_, [[Setter]]: _thrower_, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
+ 1. Perform ! DefinePropertyOrThrow(_func_, *"arguments"*, PropertyDescriptor { [[Getter]]: _thrower_, [[Setter]]: _thrower_, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
1. Return ~unused~.
-
+
%ThrowTypeError% ( )
This function is the %ThrowTypeError% intrinsic object.
It is an anonymous built-in function object that is defined once for each realm.
@@ -13474,28 +14029,28 @@ %ThrowTypeError% ( )
MakeConstructor (
- _F_: an ECMAScript function object or a built-in function object,
- optional _writablePrototype_: a Boolean,
- optional _prototype_: an Object,
+ _func_: an ECMAScript function object or a built-in function object,
+ optional _writableProto_: a Boolean,
+ optional _proto_: an Object,
): ~unused~
- description
- - It converts _F_ into a constructor.
+ - It converts _func_ into a constructor.
- 1. If _F_ is an ECMAScript function object, then
- 1. Assert: IsConstructor(_F_) is *false*.
- 1. Assert: _F_ is an extensible object that does not have a *"prototype"* own property.
- 1. Set _F_.[[Construct]] to the definition specified in
@@ -13503,14 +14058,14 @@
MakeClassConstructor (
- _F_: an ECMAScript function object,
+ _func_: an ECMAScript function object,
): ~unused~
- 1. Assert: _F_.[[IsClassConstructor]] is *false*.
- 1. Set _F_.[[IsClassConstructor]] to *true*.
+ 1. Assert: _func_.[[IsClassConstructor]] is *false*.
+ 1. Set _func_.[[IsClassConstructor]] to *true*.
1. Return ~unused~.
@@ -13518,16 +14073,17 @@
MakeMethod (
- _F_: an ECMAScript function object,
- _homeObject_: an Object,
+ _func_: an ECMAScript function object,
+ _homeObj_: an Object,
): ~unused~
- description
- - It configures _F_ as a method.
+ - It configures _func_ as a method.
- 1. Set _F_.[[HomeObject]] to _homeObject_.
+ 1. Assert: _homeObj_ is an ordinary object.
+ 1. Set _func_.[[HomeObject]] to _homeObj_.
1. Return ~unused~.
@@ -13535,8 +14091,8 @@
DefineMethodProperty (
- _homeObject_: an Object,
- _key_: a property key or Private Name,
+ _homeObj_: an Object,
+ _name_: a property key or Private Name,
_closure_: a function object,
_enumerable_: a Boolean,
): either a normal completion containing either a PrivateElement or ~unused~, or an abrupt completion
@@ -13544,44 +14100,44 @@
- 1. Assert: _homeObject_ is an ordinary, extensible object.
- 1. If _key_ is a Private Name, then
- 1. Return PrivateElement { [[Key]]: _key_, [[Kind]]: ~method~, [[Value]]: _closure_ }.
- 1. Else,
- 1. Let _desc_ be the PropertyDescriptor { [[Value]]: _closure_, [[Writable]]: *true*, [[Enumerable]]: _enumerable_, [[Configurable]]: *true* }.
- 1. Perform ? DefinePropertyOrThrow(_homeObject_, _key_, _desc_).
- 1. NOTE: DefinePropertyOrThrow only returns an abrupt completion when attempting to define a class static method whose _key_ is *"prototype"*.
- 1. Return ~unused~.
+ 1. Assert: _homeObj_ is an ordinary, extensible object.
+ 1. If _name_ is a Private Name, return PrivateElement { [[Key]]: _name_, [[Kind]]: ~method~, [[Value]]: _closure_ }.
+ 1. Let _propertyDesc_ be the PropertyDescriptor { [[Value]]: _closure_, [[Writable]]: *true*, [[Enumerable]]: _enumerable_, [[Configurable]]: *true* }.
+ 1. Perform ? DefinePropertyOrThrow(_homeObj_, _name_, _propertyDesc_).
+ 1. NOTE: DefinePropertyOrThrow only returns an abrupt completion when attempting to define a class static method whose _name_ is *"prototype"*.
+ 1. Return ~unused~.
SetFunctionName (
- _F_: a function object,
+ _func_: a function object,
_name_: a property key or Private Name,
optional _prefix_: a String,
): ~unused~
- description
- - It adds a *"name"* property to _F_.
+ - It adds a *"name"* property to _func_.
- 1. Assert: _F_ is an extensible object that does not have a *"name"* own property.
+ 1. Assert: _func_ is an extensible object that does not have a *"name"* own property.
1. If _name_ is a Symbol, then
- 1. Let _description_ be _name_'s [[Description]] value.
+ 1. Let _description_ be _name_.[[Description]].
1. If _description_ is *undefined*, set _name_ to the empty String.
1. Else, set _name_ to the string-concatenation of *"["*, _description_, and *"]"*.
1. Else if _name_ is a Private Name, then
1. Set _name_ to _name_.[[Description]].
- 1. If _F_ has an [[InitialName]] internal slot, then
- 1. Set _F_.[[InitialName]] to _name_.
+ 1. If _func_ has an [[InitialName]] internal slot, then
+ 1. Set _func_.[[InitialName]] to _name_.
1. If _prefix_ is present, then
- 1. Set _name_ to the string-concatenation of _prefix_, the code unit 0x0020 (SPACE), and _name_.
- 1. If _F_ has an [[InitialName]] internal slot, then
- 1. Optionally, set _F_.[[InitialName]] to _name_.
- 1. Perform ! DefinePropertyOrThrow(_F_, *"name"*, PropertyDescriptor { [[Value]]: _name_, [[Writable]]: *false*, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
+ 1. Let _prefixedName_ be the string-concatenation of _prefix_, the code unit 0x0020 (SPACE), and _name_.
+ 1. If _func_ has an [[InitialName]] internal slot, then
+ 1. NOTE: The choice in the following step is made independently each time this Abstract Operation is invoked.
+ 1. Set _func_.[[InitialName]] to an implementation-defined choice of either _name_ or _prefixedName_.
+ 1. Set _name_ to _prefixedName_.
+ 1. Perform ! DefinePropertyOrThrow(_func_, *"name"*, PropertyDescriptor { [[Value]]: _name_, [[Writable]]: *false*, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
1. Return ~unused~.
@@ -13589,27 +14145,27 @@
SetFunctionLength (
- _F_: a function object,
+ _func_: a function object,
_length_: a non-negative integer or +∞,
): ~unused~
- description
- - It adds a *"length"* property to _F_.
+ - It adds a *"length"* property to _func_.
- 1. Assert: _F_ is an extensible object that does not have a *"length"* own property.
- 1. Perform ! DefinePropertyOrThrow(_F_, *"length"*, PropertyDescriptor { [[Value]]: 𝔽(_length_), [[Writable]]: *false*, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
+ 1. Assert: _func_ is an extensible object that does not have a *"length"* own property.
+ 1. Perform ! DefinePropertyOrThrow(_func_, *"length"*, PropertyDescriptor { [[Value]]: 𝔽(_length_), [[Writable]]: *false*, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
1. Return ~unused~.
-
+
FunctionDeclarationInstantiation (
_func_: an ECMAScript function object,
- _argumentsList_: a List of ECMAScript language values,
- ): either a normal completion containing ~unused~ or an abrupt completion
+ _argList_: a List of ECMAScript language values,
+ ): either a normal completion containing ~unused~ or a throw completion
- description
@@ -13619,127 +14175,135 @@
When an execution context is established for evaluating an ECMAScript function a new Function Environment Record is created and bindings for each formal parameter are instantiated in that Environment Record. Each declaration in the function body is also instantiated. If the function's formal parameters do not include any default value initializers then the body declarations are instantiated in the same Environment Record as the parameters. If default value parameter initializers exist, a second Environment Record is created for the body declarations. Formal parameters and functions are initialized as part of FunctionDeclarationInstantiation. All other bindings are initialized during evaluation of the function body.
It performs the following steps when called:
-
1. Let _calleeContext_ be the running execution context.
1. Let _code_ be _func_.[[ECMAScriptCode]].
1. Let _strict_ be _func_.[[Strict]].
1. Let _formals_ be _func_.[[FormalParameters]].
- 1. Let _parameterNames_ be the BoundNames of _formals_.
- 1. If _parameterNames_ has any duplicate entries, let _hasDuplicates_ be *true*. Otherwise, let _hasDuplicates_ be *false*.
- 1. Let _simpleParameterList_ be IsSimpleParameterList of _formals_.
- 1. Let _hasParameterExpressions_ be ContainsExpression of _formals_.
- 1. Let _varNames_ be the VarDeclaredNames of _code_.
- 1. Let _varDeclarations_ be the VarScopedDeclarations of _code_.
+ 1. Let _paramNames_ be the BoundNames of _formals_.
+ 1. If _paramNames_ has any duplicate entries, let _hasDuplicates_ be *true*; else let _hasDuplicates_ be *false*.
+ 1. Let _simpleParamList_ be IsSimpleParameterList of _formals_.
+ 1. Let _hasParamExprs_ be ContainsExpression of _formals_.
+ 1. Let _variableNames_ be the VarDeclaredNames of _code_.
+ 1. Let _variableDecls_ be the VarScopedDeclarations of _code_.
1. Let _lexicalNames_ be the LexicallyDeclaredNames of _code_.
- 1. Let _functionNames_ be a new empty List.
- 1. Let _functionsToInitialize_ be a new empty List.
- 1. For each element _d_ of _varDeclarations_, in reverse List order, do
- 1. If _d_ is neither a |VariableDeclaration| nor a |ForBinding| nor a |BindingIdentifier|, then
- 1. Assert: _d_ is either a |FunctionDeclaration|, a |GeneratorDeclaration|, an |AsyncFunctionDeclaration|, or an |AsyncGeneratorDeclaration|.
- 1. Let _fn_ be the sole element of the BoundNames of _d_.
- 1. If _functionNames_ does not contain _fn_, then
- 1. Insert _fn_ as the first element of _functionNames_.
+ 1. Let _funcNames_ be a new empty List.
+ 1. Let _funcsToInitialize_ be a new empty List.
+ 1. For each element _variableDecl_ of _variableDecls_, in reverse List order, do
+ 1. If _variableDecl_ is neither a |VariableDeclaration| nor a |ForBinding| nor a |BindingIdentifier|, then
+ 1. Assert: _variableDecl_ is either a |FunctionDeclaration|, a |GeneratorDeclaration|, an |AsyncFunctionDeclaration|, or an |AsyncGeneratorDeclaration|.
+ 1. Let _funcName_ be the sole element of the BoundNames of _variableDecl_.
+ 1. If _funcNames_ does not contain _funcName_, then
+ 1. Insert _funcName_ as the first element of _funcNames_.
1. NOTE: If there are multiple function declarations for the same name, the last declaration is used.
- 1. Insert _d_ as the first element of _functionsToInitialize_.
- 1. Let _argumentsObjectNeeded_ be *true*.
+ 1. Insert _variableDecl_ as the first element of _funcsToInitialize_.
+ 1. Let _argumentsObjNeeded_ be *true*.
1. If _func_.[[ThisMode]] is ~lexical~, then
1. NOTE: Arrow functions never have an arguments object.
- 1. Set _argumentsObjectNeeded_ to *false*.
- 1. Else if _parameterNames_ contains *"arguments"*, then
- 1. Set _argumentsObjectNeeded_ to *false*.
- 1. Else if _hasParameterExpressions_ is *false*, then
- 1. If _functionNames_ contains *"arguments"* or _lexicalNames_ contains *"arguments"*, then
- 1. Set _argumentsObjectNeeded_ to *false*.
- 1. If _strict_ is *true* or _hasParameterExpressions_ is *false*, then
+ 1. Set _argumentsObjNeeded_ to *false*.
+ 1. Else if _paramNames_ contains *"arguments"*, then
+ 1. Set _argumentsObjNeeded_ to *false*.
+ 1. Else if _hasParamExprs_ is *false*, then
+ 1. If _funcNames_ contains *"arguments"* or _lexicalNames_ contains *"arguments"*, then
+ 1. Set _argumentsObjNeeded_ to *false*.
+ 1. If _strict_ is *true* or _hasParamExprs_ is *false*, then
1. NOTE: Only a single Environment Record is needed for the parameters, since calls to `eval` in strict mode code cannot create new bindings which are visible outside of the `eval`.
- 1. Let _env_ be the LexicalEnvironment of _calleeContext_.
+ 1. Let _envRecord_ be the LexicalEnvironment of _calleeContext_.
1. Else,
1. NOTE: A separate Environment Record is needed to ensure that bindings created by direct eval calls in the formal parameter list are outside the environment where parameters are declared.
1. Let _calleeEnv_ be the LexicalEnvironment of _calleeContext_.
- 1. Let _env_ be NewDeclarativeEnvironment(_calleeEnv_).
+ 1. Let _envRecord_ be NewDeclarativeEnvironment(_calleeEnv_).
1. Assert: The VariableEnvironment of _calleeContext_ and _calleeEnv_ are the same Environment Record.
- 1. Set the LexicalEnvironment of _calleeContext_ to _env_.
- 1. For each String _paramName_ of _parameterNames_, do
- 1. Let _alreadyDeclared_ be ! _env_.HasBinding(_paramName_).
+ 1. Set the LexicalEnvironment of _calleeContext_ to _envRecord_.
+ 1. For each String _paramName_ of _paramNames_, do
+ 1. Let _alreadyDeclared_ be ! _envRecord_.HasBinding(_paramName_).
1. NOTE: Early errors ensure that duplicate parameter names can only occur in non-strict functions that do not have parameter default values or rest parameters.
1. If _alreadyDeclared_ is *false*, then
- 1. Perform ! _env_.CreateMutableBinding(_paramName_, *false*).
+ 1. Perform ! _envRecord_.CreateMutableBinding(_paramName_, *false*).
1. If _hasDuplicates_ is *true*, then
- 1. Perform ! _env_.InitializeBinding(_paramName_, *undefined*).
- 1. If _argumentsObjectNeeded_ is *true*, then
- 1. If _strict_ is *true* or _simpleParameterList_ is *false*, then
- 1. Let _ao_ be CreateUnmappedArgumentsObject(_argumentsList_).
+ 1. Perform ! _envRecord_.InitializeBinding(_paramName_, *undefined*).
+ 1. If _argumentsObjNeeded_ is *true*, then
+ 1. If _strict_ is *true* or _simpleParamList_ is *false*, then
+ 1. Let _argumentsObj_ be CreateUnmappedArgumentsObject(_argList_).
1. Else,
1. NOTE: A mapped argument object is only provided for non-strict functions that don't have a rest parameter, any parameter default value initializers, or any destructured parameters.
- 1. Let _ao_ be CreateMappedArgumentsObject(_func_, _formals_, _argumentsList_, _env_).
+ 1. Let _argumentsObj_ be CreateMappedArgumentsObject(_func_, _formals_, _argList_, _envRecord_).
1. If _strict_ is *true*, then
- 1. Perform ! _env_.CreateImmutableBinding(*"arguments"*, *false*).
+ 1. Perform ! _envRecord_.CreateImmutableBinding(*"arguments"*, *false*).
1. NOTE: In strict mode code early errors prevent attempting to assign to this binding, so its mutability is not observable.
1. Else,
- 1. Perform ! _env_.CreateMutableBinding(*"arguments"*, *false*).
- 1. Perform ! _env_.InitializeBinding(*"arguments"*, _ao_).
- 1. Let _parameterBindings_ be the list-concatenation of _parameterNames_ and « *"arguments"* ».
+ 1. Perform ! _envRecord_.CreateMutableBinding(*"arguments"*, *false*).
+ 1. Perform ! _envRecord_.InitializeBinding(*"arguments"*, _argumentsObj_).
+ 1. Let _paramBindings_ be the list-concatenation of _paramNames_ and « *"arguments"* ».
1. Else,
- 1. Let _parameterBindings_ be _parameterNames_.
- 1. Let _iteratorRecord_ be CreateListIteratorRecord(_argumentsList_).
+ 1. Let _paramBindings_ be _paramNames_.
+ 1. Let _iteratorRecord_ be CreateListIteratorRecord(_argList_).
1. If _hasDuplicates_ is *true*, then
- 1. Perform ? IteratorBindingInitialization of _formals_ with arguments _iteratorRecord_ and *undefined*.
+ 1. Let _usedEnv_ be *undefined*.
1. Else,
- 1. Perform ? IteratorBindingInitialization of _formals_ with arguments _iteratorRecord_ and _env_.
- 1. If _hasParameterExpressions_ is *false*, then
+ 1. Let _usedEnv_ be _envRecord_.
+ 1. NOTE: The following step cannot return a ReturnCompletion because the only way such a completion can arise in expression position is by use of |YieldExpression|, which is forbidden in parameter lists by Early Error rules in
-
-
-
@@ -13750,6 +14314,7 @@ Built-in Function Objects
- [[Realm]], a Realm Record that represents the realm in which the function was created.
- [[InitialName]], a String that is the initial name of the function. It is used by
+ - [[Async]], a Boolean that indicates whether the function has async function call and construct behaviour in BuiltinCallOrConstruct.
The initial value of a built-in function object's [[Prototype]] internal slot is %Function.prototype%, unless otherwise specified.
A built-in function object must have a [[Call]] internal method that conforms to the definition in
@@ -13759,41 +14324,43 @@ Built-in Function Objects
[[Call]] (
- _thisArgument_: an ECMAScript language value,
- _argumentsList_: a List of ECMAScript language values,
+ _thisArg_: an ECMAScript language value,
+ _argList_: a List of ECMAScript language values,
): either a normal completion containing an ECMAScript language value or a throw completion
- for
- - a built-in function object _F_
+ - a built-in function object _func_
- 1. Return ? BuiltinCallOrConstruct(_F_, _thisArgument_, _argumentsList_, *undefined*).
+ 1. Return ? BuiltinCallOrConstruct(_func_, _thisArg_, _argList_, *undefined*).
[[Construct]] (
- _argumentsList_: a List of ECMAScript language values,
+ _argList_: a List of ECMAScript language values,
_newTarget_: a constructor,
): either a normal completion containing an Object or a throw completion
- for
- - a built-in function object _F_ (when the method is present)
+ - a built-in function object _func_ (when the method is present)
- 1. Return ? BuiltinCallOrConstruct(_F_, ~uninitialized~, _argumentsList_, _newTarget_).
+ 1. Let _result_ be ? BuiltinCallOrConstruct(_func_, ~uninitialized~, _argList_, _newTarget_).
+ 1. Assert: _result_ is an Object.
+ 1. Return _result_.
BuiltinCallOrConstruct (
- _F_: a built-in function object,
- _thisArgument_: an ECMAScript language value or ~uninitialized~,
- _argumentsList_: a List of ECMAScript language values,
+ _func_: a built-in function object,
+ _thisArg_: an ECMAScript language value or ~uninitialized~,
+ _argList_: a List of ECMAScript language values,
_newTarget_: a constructor or *undefined*,
): either a normal completion containing an ECMAScript language value or a throw completion
@@ -13803,14 +14370,23 @@
1. Let _callerContext_ be the running execution context.
1. If _callerContext_ is not already suspended, suspend _callerContext_.
1. Let _calleeContext_ be a new execution context.
- 1. Set the Function of _calleeContext_ to _F_.
- 1. Let _calleeRealm_ be _F_.[[Realm]].
+ 1. Set the Function of _calleeContext_ to _func_.
+ 1. Let _calleeRealm_ be _func_.[[Realm]].
1. Set the Realm of _calleeContext_ to _calleeRealm_.
1. Set the ScriptOrModule of _calleeContext_ to *null*.
1. Perform any necessary implementation-defined initialization of _calleeContext_.
1. Push _calleeContext_ onto the execution context stack; _calleeContext_ is now the running execution context.
- 1. [id="step-call-builtin-function-result"] Let _result_ be the Completion Record that is the result of evaluating _F_ in a manner that conforms to the specification of _F_. If _thisArgument_ is ~uninitialized~, the *this* value is uninitialized; otherwise, _thisArgument_ provides the *this* value. _argumentsList_ provides the named parameters. _newTarget_ provides the NewTarget value.
- 1. NOTE: If _F_ is defined in this document, “the specification of _F_” is the behaviour specified for it via algorithm steps or other means.
+ 1. If _func_.[[Async]] is *true*, then
+ 1. Let _promiseCapability_ be ! NewPromiseCapability(%Promise%).
+ 1. Let _resultsClosure_ be a new Abstract Closure with no parameters that captures _func_, _thisArg_, _argList_, and _newTarget_ and performs the following steps when called:
+ 1. Let _result_ be the Completion Record that is the result of evaluating _func_ in a manner that conforms to the specification of _func_. If _thisArg_ is ~uninitialized~, the *this* value is uninitialized; else _thisArg_ provides the *this* value. _argList_ provides the named parameters. _newTarget_ provides the NewTarget value.
+ 1. NOTE: If _func_ is defined in this document, “the specification of _func_” is the behaviour specified for it via algorithm steps or other means.
+ 1. Return Completion(_result_).
+ 1. Perform AsyncFunctionStart(_promiseCapability_, _resultsClosure_).
+ 1. Remove _calleeContext_ from the execution context stack and restore _callerContext_ as the running execution context.
+ 1. Return _promiseCapability_.[[Promise]].
+ 1. [id="step-call-builtin-function-result"] Let _result_ be the Completion Record that is the result of evaluating _func_ in a manner that conforms to the specification of _func_. If _thisArg_ is ~uninitialized~, the *this* value is uninitialized; else _thisArg_ provides the *this* value. _argList_ provides the named parameters. _newTarget_ provides the NewTarget value.
+ 1. NOTE: If _func_ is defined in this document, “the specification of _func_” is the behaviour specified for it via algorithm steps or other means.
1. Remove _calleeContext_ from the execution context stack and restore _callerContext_ as the running execution context.
1. Return ? _result_.
@@ -13827,9 +14403,10 @@
_name_: a property key or a Private Name,
_additionalInternalSlotsList_: a List of names of internal slots,
optional _realm_: a Realm Record,
- optional _prototype_: an Object or *null*,
+ optional _proto_: an Object or *null*,
optional _prefix_: a String,
- ): a function object
+ optional _async_: a Boolean,
+ ): a built-in function object
- description
@@ -13837,11 +14414,13 @@
1. If _realm_ is not present, set _realm_ to the current Realm Record.
- 1. If _prototype_ is not present, set _prototype_ to _realm_.[[Intrinsics]].[[%Function.prototype%]].
+ 1. If _proto_ is not present, set _proto_ to _realm_.[[Intrinsics]].[[%Function.prototype%]].
+ 1. If _async_ is not present, set _async_ to *false*.
1. Let _internalSlotsList_ be a List containing the names of all the internal slots that Bound Function Exotic Objects
Bound function exotic objects do not have the internal slots of ECMAScript function objects listed in
-
-
- Internal Slot
-
-
- Type
-
-
- Description
-
-
+
+
+
+ Internal Slot
+
+
+ Type
+
+
+ Description
+
+
+
[[BoundTargetFunction]]
@@ -13919,19 +14500,19 @@ Bound Function Exotic Objects
[[Call]] (
- _thisArgument_: an ECMAScript language value,
- _argumentsList_: a List of ECMAScript language values,
+ _thisArg_: an ECMAScript language value,
+ _argList_: a List of ECMAScript language values,
): either a normal completion containing an ECMAScript language value or a throw completion
- for
- - a bound function exotic object _F_
+ - a bound function exotic object _func_
- 1. Let _target_ be _F_.[[BoundTargetFunction]].
- 1. Let _boundThis_ be _F_.[[BoundThis]].
- 1. Let _boundArgs_ be _F_.[[BoundArguments]].
- 1. Let _args_ be the list-concatenation of _boundArgs_ and _argumentsList_.
+ 1. Let _target_ be _func_.[[BoundTargetFunction]].
+ 1. Let _boundThis_ be _func_.[[BoundThis]].
+ 1. Let _boundArgs_ be _func_.[[BoundArguments]].
+ 1. Let _args_ be the list-concatenation of _boundArgs_ and _argList_.
1. Return ? Call(_target_, _boundThis_, _args_).
@@ -13939,20 +14520,20 @@
[[Construct]] (
- _argumentsList_: a List of ECMAScript language values,
+ _argList_: a List of ECMAScript language values,
_newTarget_: a constructor,
): either a normal completion containing an Object or a throw completion
- for
- - a bound function exotic object _F_
+ - a bound function exotic object _func_
- 1. Let _target_ be _F_.[[BoundTargetFunction]].
+ 1. Let _target_ be _func_.[[BoundTargetFunction]].
1. Assert: IsConstructor(_target_) is *true*.
- 1. Let _boundArgs_ be _F_.[[BoundArguments]].
- 1. Let _args_ be the list-concatenation of _boundArgs_ and _argumentsList_.
- 1. If SameValue(_F_, _newTarget_) is *true*, set _newTarget_ to _target_.
+ 1. Let _boundArgs_ be _func_.[[BoundArguments]].
+ 1. Let _args_ be the list-concatenation of _boundArgs_ and _argList_.
+ 1. If SameValue(_func_, _newTarget_) is *true*, set _newTarget_ to _target_.
1. Return ? Construct(_target_, _args_, _newTarget_).
@@ -13960,7 +14541,7 @@
BoundFunctionCreate (
- _targetFunction_: a function object,
+ _targetFunc_: a function object,
_boundThis_: an ECMAScript language value,
_boundArgs_: a List of ECMAScript language values,
): either a normal completion containing a function object or a throw completion
@@ -13970,14 +14551,14 @@
- It is used to specify the creation of new bound function exotic objects.
- 1. Let _proto_ be ? _targetFunction_.[[GetPrototypeOf]] ().
+ 1. Let _proto_ be ? _targetFunc_.[[GetPrototypeOf]]() .
1. Let _internalSlotsList_ be the list-concatenation of « [[Prototype]], [[Extensible]] » and the internal slots listed in Array Exotic Objects
[[DefineOwnProperty]] (
- _P_: a property key,
- _Desc_: a Property Descriptor,
+ _propertyKey_: a property key,
+ _propertyDesc_: a Property Descriptor,
): either a normal completion containing a Boolean or a throw completion
- for
- - an Array exotic object _A_
+ - an Array exotic object _array_
- 1. If _P_ is *"length"*, then
- 1. Return ? ArraySetLength(_A_, _Desc_).
- 1. Else if _P_ is an array index, then
- 1. Let _lengthDesc_ be OrdinaryGetOwnProperty(_A_, *"length"*).
+ 1. If _propertyKey_ is *"length"*, return ? ArraySetLength(_array_, _propertyDesc_).
+ 1. If _propertyKey_ is an array index, then
+ 1. Let _lengthDesc_ be OrdinaryGetOwnProperty(_array_, *"length"*).
+ 1. Assert: _lengthDesc_ is not *undefined*.
1. Assert: IsDataDescriptor(_lengthDesc_) is *true*.
1. Assert: _lengthDesc_.[[Configurable]] is *false*.
1. Let _length_ be _lengthDesc_.[[Value]].
1. Assert: _length_ is a non-negative integral Number.
- 1. Let _index_ be ! ToUint32(_P_).
+ 1. Let _index_ be ! ToUint32(_propertyKey_).
1. If _index_ ≥ _length_ and _lengthDesc_.[[Writable]] is *false*, return *false*.
- 1. Let _succeeded_ be ! OrdinaryDefineOwnProperty(_A_, _P_, _Desc_).
+ 1. Let _succeeded_ be ! OrdinaryDefineOwnProperty(_array_, _propertyKey_, _propertyDesc_).
1. If _succeeded_ is *false*, return *false*.
1. If _index_ ≥ _length_, then
1. Set _lengthDesc_.[[Value]] to _index_ + *1*𝔽.
- 1. Set _succeeded_ to ! OrdinaryDefineOwnProperty(_A_, *"length"*, _lengthDesc_).
+ 1. Set _succeeded_ to ! OrdinaryDefineOwnProperty(_array_, *"length"*, _lengthDesc_).
1. Assert: _succeeded_ is *true*.
1. Return *true*.
- 1. Return ? OrdinaryDefineOwnProperty(_A_, _P_, _Desc_).
+ 1. Return ? OrdinaryDefineOwnProperty(_array_, _propertyKey_, _propertyDesc_).
@@ -14038,11 +14619,11 @@
1. If _length_ > 232 - 1, throw a *RangeError* exception.
1. If _proto_ is not present, set _proto_ to %Array.prototype%.
- 1. Let _A_ be MakeBasicObject(« [[Prototype]], [[Extensible]] »).
- 1. Set _A_.[[Prototype]] to _proto_.
- 1. Set _A_.[[DefineOwnProperty]] as specified in
@@ -14060,18 +14641,18 @@
1. Let _isArray_ be ? IsArray(_originalArray_).
1. If _isArray_ is *false*, return ? ArrayCreate(_length_).
- 1. Let _C_ be ? Get(_originalArray_, *"constructor"*).
- 1. If IsConstructor(_C_) is *true*, then
+ 1. Let _ctor_ be ? Get(_originalArray_, *"constructor"*).
+ 1. If IsConstructor(_ctor_) is *true*, then
1. Let _thisRealm_ be the current Realm Record.
- 1. Let _realmC_ be ? GetFunctionRealm(_C_).
- 1. If _thisRealm_ and _realmC_ are not the same Realm Record, then
- 1. If SameValue(_C_, _realmC_.[[Intrinsics]].[[%Array%]]) is *true*, set _C_ to *undefined*.
- 1. If _C_ is an Object, then
- 1. Set _C_ to ? Get(_C_, @@species).
- 1. If _C_ is *null*, set _C_ to *undefined*.
- 1. If _C_ is *undefined*, return ? ArrayCreate(_length_).
- 1. If IsConstructor(_C_) is *false*, throw a *TypeError* exception.
- 1. Return ? Construct(_C_, « 𝔽(_length_) »).
+ 1. Let _ctorRealm_ be ? GetFunctionRealm(_ctor_).
+ 1. If _thisRealm_ and _ctorRealm_ are not the same Realm Record, then
+ 1. If SameValue(_ctor_, _ctorRealm_.[[Intrinsics]].[[%Array%]]) is *true*, set _ctor_ to *undefined*.
+ 1. If _ctor_ is an Object, then
+ 1. Set _ctor_ to ? Get(_ctor_, %Symbol.species%).
+ 1. If _ctor_ is *null*, set _ctor_ to *undefined*.
+ 1. If _ctor_ is *undefined*, return ? ArrayCreate(_length_).
+ 1. If IsConstructor(_ctor_) is *false*, throw a *TypeError* exception.
+ 1. Return ? Construct(_ctor_, « 𝔽(_length_) »).
If _originalArray_ was created using the standard built-in Array constructor for a realm that is not the realm of the running execution context, then a new Array is created using the realm of the running execution context. This maintains compatibility with Web browsers that have historically had that behaviour for the `Array.prototype` methods that now are defined using ArraySpeciesCreate.
@@ -14081,49 +14662,50 @@
ArraySetLength (
- _A_: an Array,
- _Desc_: a Property Descriptor,
+ _array_: an Array,
+ _propertyDesc_: a Property Descriptor,
): either a normal completion containing a Boolean or a throw completion
- 1. If _Desc_ does not have a [[Value]] field, then
- 1. Return ! OrdinaryDefineOwnProperty(_A_, *"length"*, _Desc_).
- 1. Let _newLenDesc_ be a copy of _Desc_.
- 1. [id="step-arraysetlength-newlen"] Let _newLen_ be ? ToUint32(_Desc_.[[Value]]).
- 1. [id="step-arraysetlength-numberlen"] Let _numberLen_ be ? ToNumber(_Desc_.[[Value]]).
- 1. If SameValueZero(_newLen_, _numberLen_) is *false*, throw a *RangeError* exception.
- 1. Set _newLenDesc_.[[Value]] to _newLen_.
- 1. Let _oldLenDesc_ be OrdinaryGetOwnProperty(_A_, *"length"*).
- 1. Assert: IsDataDescriptor(_oldLenDesc_) is *true*.
- 1. Assert: _oldLenDesc_.[[Configurable]] is *false*.
- 1. Let _oldLen_ be _oldLenDesc_.[[Value]].
- 1. If _newLen_ ≥ _oldLen_, then
- 1. Return ! OrdinaryDefineOwnProperty(_A_, *"length"*, _newLenDesc_).
- 1. If _oldLenDesc_.[[Writable]] is *false*, return *false*.
- 1. If _newLenDesc_ does not have a [[Writable]] field or _newLenDesc_.[[Writable]] is *true*, then
+ 1. If _propertyDesc_ does not have a [[Value]] field, then
+ 1. Return ! OrdinaryDefineOwnProperty(_array_, *"length"*, _propertyDesc_).
+ 1. Let _newLengthDesc_ be a copy of _propertyDesc_.
+ 1. [id="step-arraysetlength-newlen"] Let _newLength_ be ? ToUint32(_propertyDesc_.[[Value]]).
+ 1. [id="step-arraysetlength-numberlen"] Let _numberLength_ be ? ToNumber(_propertyDesc_.[[Value]]).
+ 1. If SameValueZero(_newLength_, _numberLength_) is *false*, throw a *RangeError* exception.
+ 1. Set _newLengthDesc_.[[Value]] to _newLength_.
+ 1. Let _oldLengthDesc_ be OrdinaryGetOwnProperty(_array_, *"length"*).
+ 1. Assert: _oldLengthDesc_ is not *undefined*.
+ 1. Assert: IsDataDescriptor(_oldLengthDesc_) is *true*.
+ 1. Assert: _oldLengthDesc_.[[Configurable]] is *false*.
+ 1. Let _oldLength_ be _oldLengthDesc_.[[Value]].
+ 1. If _newLength_ ≥ _oldLength_, then
+ 1. Return ! OrdinaryDefineOwnProperty(_array_, *"length"*, _newLengthDesc_).
+ 1. If _oldLengthDesc_.[[Writable]] is *false*, return *false*.
+ 1. If _newLengthDesc_ does not have a [[Writable]] field or _newLengthDesc_.[[Writable]] is *true*, then
1. Let _newWritable_ be *true*.
1. Else,
1. NOTE: Setting the [[Writable]] attribute to *false* is deferred in case any elements cannot be deleted.
1. Let _newWritable_ be *false*.
- 1. Set _newLenDesc_.[[Writable]] to *true*.
- 1. Let _succeeded_ be ! OrdinaryDefineOwnProperty(_A_, *"length"*, _newLenDesc_).
+ 1. Set _newLengthDesc_.[[Writable]] to *true*.
+ 1. Let _succeeded_ be ! OrdinaryDefineOwnProperty(_array_, *"length"*, _newLengthDesc_).
1. If _succeeded_ is *false*, return *false*.
- 1. For each own property key _P_ of _A_ such that _P_ is an array index and ! ToUint32(_P_) ≥ _newLen_, in descending numeric index order, do
- 1. Let _deleteSucceeded_ be ! _A_.[[Delete]](_P_).
+ 1. For each own property key _propertyKey_ of _array_ such that _propertyKey_ is an array index and ! ToUint32(_propertyKey_) ≥ _newLength_, in descending numeric index order, do
+ 1. Let _deleteSucceeded_ be ! _array_.[[Delete]](_propertyKey_).
1. If _deleteSucceeded_ is *false*, then
- 1. Set _newLenDesc_.[[Value]] to ! ToUint32(_P_) + *1*𝔽.
- 1. If _newWritable_ is *false*, set _newLenDesc_.[[Writable]] to *false*.
- 1. Perform ! OrdinaryDefineOwnProperty(_A_, *"length"*, _newLenDesc_).
+ 1. Set _newLengthDesc_.[[Value]] to ! ToUint32(_propertyKey_) + *1*𝔽.
+ 1. If _newWritable_ is *false*, set _newLengthDesc_.[[Writable]] to *false*.
+ 1. Perform ! OrdinaryDefineOwnProperty(_array_, *"length"*, _newLengthDesc_).
1. Return *false*.
1. If _newWritable_ is *false*, then
- 1. Set _succeeded_ to ! OrdinaryDefineOwnProperty(_A_, *"length"*, PropertyDescriptor { [[Writable]]: *false* }).
+ 1. Set _succeeded_ to ! OrdinaryDefineOwnProperty(_array_, *"length"*, PropertyDescriptor { [[Writable]]: *false* }).
1. Assert: _succeeded_ is *true*.
1. Return *true*.
- In steps
+ In steps
@@ -14139,37 +14721,37 @@ String Exotic Objects
[[GetOwnProperty]] (
- _P_: a property key,
+ _propertyKey_: a property key,
): a normal completion containing either a Property Descriptor or *undefined*
- for
- - a String exotic object _S_
+ - a String exotic object _string_
- 1. Let _desc_ be OrdinaryGetOwnProperty(_S_, _P_).
- 1. If _desc_ is not *undefined*, return _desc_.
- 1. Return StringGetOwnProperty(_S_, _P_).
+ 1. Let _propertyDesc_ be OrdinaryGetOwnProperty(_string_, _propertyKey_).
+ 1. If _propertyDesc_ is not *undefined*, return _propertyDesc_.
+ 1. Return StringGetOwnProperty(_string_, _propertyKey_).
[[DefineOwnProperty]] (
- _P_: a property key,
- _Desc_: a Property Descriptor,
+ _propertyKey_: a property key,
+ _propertyDesc_: a Property Descriptor,
): a normal completion containing a Boolean
- for
- - a String exotic object _S_
+ - a String exotic object _string_
- 1. Let _stringDesc_ be StringGetOwnProperty(_S_, _P_).
+ 1. Let _stringDesc_ be StringGetOwnProperty(_string_, _propertyKey_).
1. If _stringDesc_ is not *undefined*, then
- 1. Let _extensible_ be _S_.[[Extensible]].
- 1. Return IsCompatiblePropertyDescriptor(_extensible_, _Desc_, _stringDesc_).
- 1. Return ! OrdinaryDefineOwnProperty(_S_, _P_, _Desc_).
+ 1. Let _extensible_ be _string_.[[Extensible]].
+ 1. Return IsCompatiblePropertyDescriptor(_extensible_, _propertyDesc_, _stringDesc_).
+ 1. Return ! OrdinaryDefineOwnProperty(_string_, _propertyKey_, _propertyDesc_).
@@ -14177,21 +14759,21 @@
[[OwnPropertyKeys]] ( ): a normal completion containing a List of property keys
- for
- - a String exotic object _O_
+ - a String exotic object _obj_
1. Let _keys_ be a new empty List.
- 1. Let _str_ be _O_.[[StringData]].
- 1. Assert: _str_ is a String.
- 1. Let _len_ be the length of _str_.
- 1. For each integer _i_ such that 0 ≤ _i_ < _len_, in ascending order, do
+ 1. Let _string_ be _obj_.[[StringData]].
+ 1. Assert: _string_ is a String.
+ 1. Let _length_ be the length of _string_.
+ 1. For each integer _i_ such that 0 ≤ _i_ < _length_, in ascending order, do
1. Append ! ToString(𝔽(_i_)) to _keys_.
- 1. For each own property key _P_ of _O_ such that _P_ is an array index and ! ToIntegerOrInfinity(_P_) ≥ _len_, in ascending numeric index order, do
- 1. Append _P_ to _keys_.
- 1. For each own property key _P_ of _O_ such that _P_ is a String and _P_ is not an array index, in ascending chronological order of property creation, do
- 1. Append _P_ to _keys_.
- 1. For each own property key _P_ of _O_ such that _P_ is a Symbol, in ascending chronological order of property creation, do
- 1. Append _P_ to _keys_.
+ 1. For each own property key _propertyKey_ of _obj_ such that _propertyKey_ is an array index and ! ToIntegerOrInfinity(_propertyKey_) ≥ _length_, in ascending numeric index order, do
+ 1. Append _propertyKey_ to _keys_.
+ 1. For each own property key _propertyKey_ of _obj_ such that _propertyKey_ is a String and _propertyKey_ is not an array index, in ascending chronological order of property creation, do
+ 1. Append _propertyKey_ to _keys_.
+ 1. For each own property key _propertyKey_ of _obj_ such that _propertyKey_ is a Symbol, in ascending chronological order of property creation, do
+ 1. Append _propertyKey_ to _keys_.
1. Return _keys_.
@@ -14200,7 +14782,7 @@ [[OwnPropertyKeys]] ( ): a normal completion containing a List of property k
StringCreate (
_value_: a String,
- _prototype_: an Object,
+ _proto_: an Object,
): a String exotic object
@@ -14208,39 +14790,38 @@
- It is used to specify the creation of new String exotic objects.
- 1. Let _S_ be MakeBasicObject(« [[Prototype]], [[Extensible]], [[StringData]] »).
- 1. Set _S_.[[Prototype]] to _prototype_.
- 1. Set _S_.[[StringData]] to _value_.
- 1. Set _S_.[[GetOwnProperty]] as specified in
StringGetOwnProperty (
- _S_: an Object that has a [[StringData]] internal slot,
- _P_: a property key,
+ _string_: an Object that has a [[StringData]] internal slot,
+ _propertyKey_: a property key,
): a Property Descriptor or *undefined*
- 1. If _P_ is not a String, return *undefined*.
- 1. Let _index_ be CanonicalNumericIndexString(_P_).
- 1. If _index_ is *undefined*, return *undefined*.
- 1. If IsIntegralNumber(_index_) is *false*, return *undefined*.
- 1. If _index_ is *-0*𝔽, return *undefined*.
- 1. Let _str_ be _S_.[[StringData]].
- 1. Assert: _str_ is a String.
- 1. Let _len_ be the length of _str_.
- 1. If ℝ(_index_) < 0 or _len_ ≤ ℝ(_index_), return *undefined*.
- 1. Let _resultStr_ be the substring of _str_ from ℝ(_index_) to ℝ(_index_) + 1.
- 1. Return the PropertyDescriptor { [[Value]]: _resultStr_, [[Writable]]: *false*, [[Enumerable]]: *true*, [[Configurable]]: *false* }.
+ 1. If _propertyKey_ is not a String, return *undefined*.
+ 1. Let _numericIndex_ be CanonicalNumericIndexString(_propertyKey_).
+ 1. If _numericIndex_ is not an integral Number, return *undefined*.
+ 1. If _numericIndex_ is *-0*𝔽 or _numericIndex_ < *-0*𝔽, return *undefined*.
+ 1. Let _stringData_ be _string_.[[StringData]].
+ 1. Assert: _stringData_ is a String.
+ 1. Let _length_ be the length of _stringData_.
+ 1. If ℝ(_numericIndex_) ≥ _length_, return *undefined*.
+ 1. Let _resultString_ be the substring of _stringData_ from ℝ(_numericIndex_) to ℝ(_numericIndex_) + 1.
+ 1. Return the PropertyDescriptor { [[Value]]: _resultString_, [[Writable]]: *false*, [[Enumerable]]: *true*, [[Configurable]]: *false* }.
@@ -14256,7 +14837,7 @@ Arguments Exotic Objects
While CreateUnmappedArgumentsObject is grouped into this clause, it creates an ordinary object, not an arguments exotic object.
-
Arguments exotic objects have the same internal slots as ordinary objects. They also have a [[ParameterMap]] internal slot. Ordinary arguments objects also have a [[ParameterMap]] internal slot whose value is always undefined. For ordinary argument objects the [[ParameterMap]] internal slot is only used by `Object.prototype.toString` (
+ Arguments exotic objects have the same internal slots as ordinary objects. They also have a [[ParameterMap]] internal slot. Ordinary arguments objects also have a [[ParameterMap]] internal slot whose value is always *undefined*. For ordinary argument objects the [[ParameterMap]] internal slot is only used by `Object.prototype.toString` (
The integer-indexed data properties of an arguments exotic object whose numeric name values are less than the number of formal parameters of the corresponding function object initially share their values with the corresponding argument bindings in the function's execution context. This means that changing the property changes the corresponding value of the argument binding and vice-versa. This correspondence is broken if such a property is deleted and then redefined or if the property is changed into an accessor property. If the arguments object is an ordinary object, the values of its properties are simply a copy of the arguments passed to the function and there is no dynamic linkage between the property values and the formal parameter values.
@@ -14274,7 +14855,7 @@ Arguments Exotic Objects
[[GetOwnProperty]] (
- _P_: a property key,
+ _propertyKey_: a property key,
): a normal completion containing either a Property Descriptor or *undefined*
@@ -14282,21 +14863,21 @@
- an arguments exotic object _args_
- 1. Let _desc_ be OrdinaryGetOwnProperty(_args_, _P_).
- 1. If _desc_ is *undefined*, return *undefined*.
+ 1. Let _propertyDesc_ be OrdinaryGetOwnProperty(_args_, _propertyKey_).
+ 1. If _propertyDesc_ is *undefined*, return *undefined*.
1. Let _map_ be _args_.[[ParameterMap]].
- 1. Let _isMapped_ be ! HasOwnProperty(_map_, _P_).
+ 1. Let _isMapped_ be ! HasOwnProperty(_map_, _propertyKey_).
1. If _isMapped_ is *true*, then
- 1. Set _desc_.[[Value]] to ! Get(_map_, _P_).
- 1. Return _desc_.
+ 1. Set _propertyDesc_.[[Value]] to ! Get(_map_, _propertyKey_).
+ 1. Return _propertyDesc_.
[[DefineOwnProperty]] (
- _P_: a property key,
- _Desc_: a Property Descriptor,
+ _propertyKey_: a property key,
+ _propertyDesc_: a Property Descriptor,
): a normal completion containing a Boolean
@@ -14305,23 +14886,23 @@
1. Let _map_ be _args_.[[ParameterMap]].
- 1. Let _isMapped_ be ! HasOwnProperty(_map_, _P_).
- 1. Let _newArgDesc_ be _Desc_.
- 1. If _isMapped_ is *true* and IsDataDescriptor(_Desc_) is *true*, then
- 1. If _Desc_ does not have a [[Value]] field, _Desc_ has a [[Writable]] field, and _Desc_.[[Writable]] is *false*, then
- 1. Set _newArgDesc_ to a copy of _Desc_.
- 1. Set _newArgDesc_.[[Value]] to ! Get(_map_, _P_).
- 1. Let _allowed_ be ! OrdinaryDefineOwnProperty(_args_, _P_, _newArgDesc_).
+ 1. Let _isMapped_ be ! HasOwnProperty(_map_, _propertyKey_).
+ 1. Let _newArgDesc_ be _propertyDesc_.
+ 1. If _isMapped_ is *true* and IsDataDescriptor(_propertyDesc_) is *true*, then
+ 1. If _propertyDesc_ does not have a [[Value]] field, _propertyDesc_ has a [[Writable]] field, and _propertyDesc_.[[Writable]] is *false*, then
+ 1. Set _newArgDesc_ to a copy of _propertyDesc_.
+ 1. Set _newArgDesc_.[[Value]] to ! Get(_map_, _propertyKey_).
+ 1. Let _allowed_ be ! OrdinaryDefineOwnProperty(_args_, _propertyKey_, _newArgDesc_).
1. If _allowed_ is *false*, return *false*.
1. If _isMapped_ is *true*, then
- 1. If IsAccessorDescriptor(_Desc_) is *true*, then
- 1. Perform ! _map_.[[Delete]](_P_).
+ 1. If IsAccessorDescriptor(_propertyDesc_) is *true*, then
+ 1. Perform ! _map_.[[Delete]](_propertyKey_).
1. Else,
- 1. If _Desc_ has a [[Value]] field, then
+ 1. If _propertyDesc_ has a [[Value]] field, then
1. Assert: The following Set will succeed, since formal parameters mapped by arguments objects are always writable.
- 1. Perform ! Set(_map_, _P_, _Desc_.[[Value]], *false*).
- 1. If _Desc_ has a [[Writable]] field and _Desc_.[[Writable]] is *false*, then
- 1. Perform ! _map_.[[Delete]](_P_).
+ 1. Perform ! Set(_map_, _propertyKey_, _propertyDesc_.[[Value]], *false*).
+ 1. If _propertyDesc_ has a [[Writable]] field and _propertyDesc_.[[Writable]] is *false*, then
+ 1. Perform ! _map_.[[Delete]](_propertyKey_).
1. Return *true*.
@@ -14329,8 +14910,8 @@
[[Get]] (
- _P_: a property key,
- _Receiver_: an ECMAScript language value,
+ _propertyKey_: a property key,
+ _receiver_: an ECMAScript language value,
): either a normal completion containing an ECMAScript language value or a throw completion
@@ -14339,21 +14920,19 @@
1. Let _map_ be _args_.[[ParameterMap]].
- 1. Let _isMapped_ be ! HasOwnProperty(_map_, _P_).
- 1. If _isMapped_ is *false*, then
- 1. Return ? OrdinaryGet(_args_, _P_, _Receiver_).
- 1. Else,
- 1. Assert: _map_ contains a formal parameter mapping for _P_.
- 1. Return ! Get(_map_, _P_).
+ 1. Let _isMapped_ be ! HasOwnProperty(_map_, _propertyKey_).
+ 1. If _isMapped_ is *false*, return ? OrdinaryGet(_args_, _propertyKey_, _receiver_).
+ 1. Assert: _map_ contains a formal parameter mapping for _propertyKey_.
+ 1. Return ! Get(_map_, _propertyKey_).
[[Set]] (
- _P_: a property key,
- _V_: an ECMAScript language value,
- _Receiver_: an ECMAScript language value,
+ _propertyKey_: a property key,
+ _value_: an ECMAScript language value,
+ _receiver_: an ECMAScript language value,
): either a normal completion containing a Boolean or a throw completion
@@ -14361,22 +14940,22 @@
- an arguments exotic object _args_
- 1. If SameValue(_args_, _Receiver_) is *false*, then
+ 1. If SameValue(_args_, _receiver_) is *false*, then
1. Let _isMapped_ be *false*.
1. Else,
1. Let _map_ be _args_.[[ParameterMap]].
- 1. Let _isMapped_ be ! HasOwnProperty(_map_, _P_).
+ 1. Let _isMapped_ be ! HasOwnProperty(_map_, _propertyKey_).
1. If _isMapped_ is *true*, then
1. Assert: The following Set will succeed, since formal parameters mapped by arguments objects are always writable.
- 1. Perform ! Set(_map_, _P_, _V_, *false*).
- 1. Return ? OrdinarySet(_args_, _P_, _V_, _Receiver_).
+ 1. Perform ! Set(_map_, _propertyKey_, _value_, *false*).
+ 1. Return ? OrdinarySet(_args_, _propertyKey_, _value_, _receiver_).
[[Delete]] (
- _P_: a property key,
+ _propertyKey_: a property key,
): either a normal completion containing a Boolean or a throw completion
@@ -14385,10 +14964,10 @@
1. Let _map_ be _args_.[[ParameterMap]].
- 1. Let _isMapped_ be ! HasOwnProperty(_map_, _P_).
- 1. Let _result_ be ? OrdinaryDelete(_args_, _P_).
+ 1. Let _isMapped_ be ! HasOwnProperty(_map_, _propertyKey_).
+ 1. Let _result_ be ? OrdinaryDelete(_args_, _propertyKey_).
1. If _result_ is *true* and _isMapped_ is *true*, then
- 1. Perform ! _map_.[[Delete]](_P_).
+ 1. Perform ! _map_.[[Delete]](_propertyKey_).
1. Return _result_.
@@ -14396,23 +14975,23 @@
CreateUnmappedArgumentsObject (
- _argumentsList_: a List of ECMAScript language values,
+ _argList_: a List of ECMAScript language values,
): an ordinary object
- 1. Let _len_ be the number of elements in _argumentsList_.
+ 1. Let _length_ be the number of elements in _argList_.
1. Let _obj_ be OrdinaryObjectCreate(%Object.prototype%, « [[ParameterMap]] »).
1. Set _obj_.[[ParameterMap]] to *undefined*.
- 1. Perform ! DefinePropertyOrThrow(_obj_, *"length"*, PropertyDescriptor { [[Value]]: 𝔽(_len_), [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
+ 1. Perform ! DefinePropertyOrThrow(_obj_, *"length"*, PropertyDescriptor { [[Value]]: 𝔽(_length_), [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
1. Let _index_ be 0.
- 1. Repeat, while _index_ < _len_,
- 1. Let _val_ be _argumentsList_[_index_].
- 1. Perform ! CreateDataPropertyOrThrow(_obj_, ! ToString(𝔽(_index_)), _val_).
+ 1. Repeat, while _index_ < _length_,
+ 1. Let _value_ be _argList_[_index_].
+ 1. Perform ! CreateDataPropertyOrThrow(_obj_, ! ToString(𝔽(_index_)), _value_).
1. Set _index_ to _index_ + 1.
- 1. Perform ! DefinePropertyOrThrow(_obj_, @@iterator, PropertyDescriptor { [[Value]]: %Array.prototype.values%, [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
- 1. Perform ! DefinePropertyOrThrow(_obj_, *"callee"*, PropertyDescriptor { [[Get]]: %ThrowTypeError%, [[Set]]: %ThrowTypeError%, [[Enumerable]]: *false*, [[Configurable]]: *false* }).
+ 1. Perform ! DefinePropertyOrThrow(_obj_, %Symbol.iterator%, PropertyDescriptor { [[Value]]: %Array.prototype.values%, [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
+ 1. Perform ! DefinePropertyOrThrow(_obj_, *"callee"*, PropertyDescriptor { [[Getter]]: %ThrowTypeError%, [[Setter]]: %ThrowTypeError%, [[Enumerable]]: *false*, [[Configurable]]: *false* }).
1. Return _obj_.
@@ -14420,17 +14999,17 @@
CreateMappedArgumentsObject (
- _func_: an Object,
+ _func_: an ECMAScript function object,
_formals_: a Parse Node,
- _argumentsList_: a List of ECMAScript language values,
- _env_: an Environment Record,
+ _argList_: a List of ECMAScript language values,
+ _envRecord_: an Environment Record,
): an arguments exotic object
1. Assert: _formals_ does not contain a rest parameter, any binding patterns, or any initializers. It may contain duplicate identifiers.
- 1. Let _len_ be the number of elements in _argumentsList_.
+ 1. Let _length_ be the number of elements in _argList_.
1. Let _obj_ be MakeBasicObject(« [[Prototype]], [[Extensible]], [[ParameterMap]] »).
1. Set _obj_.[[GetOwnProperty]] as specified in
1. Set _obj_.[[Prototype]] to %Object.prototype%.
1. Let _map_ be OrdinaryObjectCreate(*null*).
1. Set _obj_.[[ParameterMap]] to _map_.
- 1. Let _parameterNames_ be the BoundNames of _formals_.
- 1. Let _numberOfParameters_ be the number of elements in _parameterNames_.
+ 1. Let _paramNames_ be the BoundNames of _formals_.
+ 1. Let _paramCount_ be the number of elements in _paramNames_.
1. Let _index_ be 0.
- 1. Repeat, while _index_ < _len_,
- 1. Let _val_ be _argumentsList_[_index_].
- 1. Perform ! CreateDataPropertyOrThrow(_obj_, ! ToString(𝔽(_index_)), _val_).
+ 1. Repeat, while _index_ < _length_,
+ 1. Let _value_ be _argList_[_index_].
+ 1. Perform ! CreateDataPropertyOrThrow(_obj_, ! ToString(𝔽(_index_)), _value_).
1. Set _index_ to _index_ + 1.
- 1. Perform ! DefinePropertyOrThrow(_obj_, *"length"*, PropertyDescriptor { [[Value]]: 𝔽(_len_), [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
+ 1. Perform ! DefinePropertyOrThrow(_obj_, *"length"*, PropertyDescriptor { [[Value]]: 𝔽(_length_), [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
1. Let _mappedNames_ be a new empty List.
- 1. Set _index_ to _numberOfParameters_ - 1.
+ 1. Set _index_ to _paramCount_ - 1.
1. Repeat, while _index_ ≥ 0,
- 1. Let _name_ be _parameterNames_[_index_].
+ 1. Let _name_ be _paramNames_[_index_].
1. If _mappedNames_ does not contain _name_, then
1. Append _name_ to _mappedNames_.
- 1. If _index_ < _len_, then
- 1. Let _g_ be MakeArgGetter(_name_, _env_).
- 1. Let _p_ be MakeArgSetter(_name_, _env_).
- 1. Perform ! _map_.[[DefineOwnProperty]](! ToString(𝔽(_index_)), PropertyDescriptor { [[Set]]: _p_, [[Get]]: _g_, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
+ 1. If _index_ < _length_, then
+ 1. Let _getter_ be MakeArgGetter(_name_, _envRecord_).
+ 1. Let _setter_ be MakeArgSetter(_name_, _envRecord_).
+ 1. Perform ! _map_.[[DefineOwnProperty]](! ToString(𝔽(_index_)), PropertyDescriptor { [[Setter]]: _setter_, [[Getter]]: _getter_, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
1. Set _index_ to _index_ - 1.
- 1. Perform ! DefinePropertyOrThrow(_obj_, @@iterator, PropertyDescriptor { [[Value]]: %Array.prototype.values%, [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
+ 1. Perform ! DefinePropertyOrThrow(_obj_, %Symbol.iterator%, PropertyDescriptor { [[Value]]: %Array.prototype.values%, [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
1. Perform ! DefinePropertyOrThrow(_obj_, *"callee"*, PropertyDescriptor { [[Value]]: _func_, [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
1. Return _obj_.
@@ -14468,16 +15047,16 @@
MakeArgGetter (
_name_: a String,
- _env_: an Environment Record,
+ _envRecord_: an Environment Record,
): a function object
- description
- - It creates a built-in function object that when executed returns the value bound for _name_ in _env_.
+ - It creates a built-in function object that when executed returns the value bound for _name_ in _envRecord_.
- 1. Let _getterClosure_ be a new Abstract Closure with no parameters that captures _name_ and _env_ and performs the following steps when called:
- 1. Return _env_.GetBindingValue(_name_, *false*).
+ 1. Let _getterClosure_ be a new Abstract Closure with no parameters that captures _name_ and _envRecord_ and performs the following steps when called:
+ 1. Return NormalCompletion(! _envRecord_.GetBindingValue(_name_, *false*)).
1. Let _getter_ be CreateBuiltinFunction(_getterClosure_, 0, *""*, « »).
1. NOTE: _getter_ is never directly accessible to ECMAScript code.
1. Return _getter_.
@@ -14488,16 +15067,16 @@
MakeArgSetter (
_name_: a String,
- _env_: an Environment Record,
+ _envRecord_: an Environment Record,
): a function object
- description
- - It creates a built-in function object that when executed sets the value bound for _name_ in _env_.
+ - It creates a built-in function object that when executed sets the value bound for _name_ in _envRecord_.
- 1. Let _setterClosure_ be a new Abstract Closure with parameters (_value_) that captures _name_ and _env_ and performs the following steps when called:
- 1. Return ! _env_.SetMutableBinding(_name_, _value_, *false*).
+ 1. Let _setterClosure_ be a new Abstract Closure with parameters (_value_) that captures _name_ and _envRecord_ and performs the following steps when called:
+ 1. Return NormalCompletion(! _envRecord_.SetMutableBinding(_name_, _value_, *false*)).
1. Let _setter_ be CreateBuiltinFunction(_setterClosure_, 1, *""*, « »).
1. NOTE: _setter_ is never directly accessible to ECMAScript code.
1. Return _setter_.
@@ -14508,135 +15087,152 @@
TypedArray Exotic Objects
- A TypedArray is an exotic object that performs special handling of integer index property keys.
- TypedArrays have the same internal slots as ordinary objects and additionally [[ViewedArrayBuffer]], [[ArrayLength]], [[ByteOffset]], [[ContentType]], and [[TypedArrayName]] internal slots.
- An object is a TypedArray if its [[GetOwnProperty]], [[HasProperty]], [[DefineOwnProperty]], [[Get]], [[Set]], [[Delete]], and [[OwnPropertyKeys]] internal methods use the definitions in this section, and its other essential internal methods use the definitions found in
+ A TypedArray is an exotic object that performs special handling of property keys that are canonical numeric strings, using the subset that are in-bounds integer indices to index elements of uniform type and enforcing the invariant that the remainder are absent without incurring prototype chain traversal.
+
+ Because ToString(_n_) for any Number _n_ is a canonical numeric string, an implementation may treat Numbers as property keys for TypedArrays without actually performing the string conversion.
+
+ TypedArrays have the same internal slots as ordinary objects and additionally [[ViewedArrayBuffer]], [[TypedArrayName]], [[ContentType]], [[ByteLength]], [[ByteOffset]], and [[ArrayLength]] internal slots.
+ An object is a TypedArray if its [[PreventExtensions]], [[GetOwnProperty]], [[HasProperty]], [[DefineOwnProperty]], [[Get]], [[Set]], [[Delete]], and [[OwnPropertyKeys]], internal methods use the definitions in this section, and its other essential internal methods use the definitions found in
+
+
+ [[PreventExtensions]] ( ): a normal completion containing a Boolean
+
+ - for
+ - a TypedArray _obj_
+
+
+ 1. NOTE: The extensibility-related invariants specified in
+
[[GetOwnProperty]] (
- _P_: a property key,
+ _propertyKey_: a property key,
): a normal completion containing either a Property Descriptor or *undefined*
- for
- - a TypedArray _O_
+ - a TypedArray _obj_
- 1. If _P_ is a String, then
- 1. Let _numericIndex_ be CanonicalNumericIndexString(_P_).
+ 1. If _propertyKey_ is a String, then
+ 1. Let _numericIndex_ be CanonicalNumericIndexString(_propertyKey_).
1. If _numericIndex_ is not *undefined*, then
- 1. Let _value_ be TypedArrayGetElement(_O_, _numericIndex_).
+ 1. Let _value_ be TypedArrayGetElement(_obj_, _numericIndex_).
1. If _value_ is *undefined*, return *undefined*.
1. Return the PropertyDescriptor { [[Value]]: _value_, [[Writable]]: *true*, [[Enumerable]]: *true*, [[Configurable]]: *true* }.
- 1. Return OrdinaryGetOwnProperty(_O_, _P_).
+ 1. Return OrdinaryGetOwnProperty(_obj_, _propertyKey_).
[[HasProperty]] (
- _P_: a property key,
+ _propertyKey_: a property key,
): either a normal completion containing a Boolean or a throw completion
- for
- - a TypedArray _O_
+ - a TypedArray _obj_
- 1. If _P_ is a String, then
- 1. Let _numericIndex_ be CanonicalNumericIndexString(_P_).
- 1. If _numericIndex_ is not *undefined*, return IsValidIntegerIndex(_O_, _numericIndex_).
- 1. Return ? OrdinaryHasProperty(_O_, _P_).
+ 1. If _propertyKey_ is a String, then
+ 1. Let _numericIndex_ be CanonicalNumericIndexString(_propertyKey_).
+ 1. If _numericIndex_ is not *undefined*, return IsValidIntegerIndex(_obj_, _numericIndex_).
+ 1. Return ? OrdinaryHasProperty(_obj_, _propertyKey_).
[[DefineOwnProperty]] (
- _P_: a property key,
- _Desc_: a Property Descriptor,
+ _propertyKey_: a property key,
+ _propertyDesc_: a Property Descriptor,
): either a normal completion containing a Boolean or a throw completion
- for
- - a TypedArray _O_
+ - a TypedArray _obj_
- 1. If _P_ is a String, then
- 1. Let _numericIndex_ be CanonicalNumericIndexString(_P_).
+ 1. If _propertyKey_ is a String, then
+ 1. Let _numericIndex_ be CanonicalNumericIndexString(_propertyKey_).
1. If _numericIndex_ is not *undefined*, then
- 1. If IsValidIntegerIndex(_O_, _numericIndex_) is *false*, return *false*.
- 1. If _Desc_ has a [[Configurable]] field and _Desc_.[[Configurable]] is *false*, return *false*.
- 1. If _Desc_ has an [[Enumerable]] field and _Desc_.[[Enumerable]] is *false*, return *false*.
- 1. If IsAccessorDescriptor(_Desc_) is *true*, return *false*.
- 1. If _Desc_ has a [[Writable]] field and _Desc_.[[Writable]] is *false*, return *false*.
- 1. If _Desc_ has a [[Value]] field, perform ? TypedArraySetElement(_O_, _numericIndex_, _Desc_.[[Value]]).
+ 1. If IsValidIntegerIndex(_obj_, _numericIndex_) is *false*, return *false*.
+ 1. If _propertyDesc_ has a [[Configurable]] field and _propertyDesc_.[[Configurable]] is *false*, return *false*.
+ 1. If _propertyDesc_ has an [[Enumerable]] field and _propertyDesc_.[[Enumerable]] is *false*, return *false*.
+ 1. If IsAccessorDescriptor(_propertyDesc_) is *true*, return *false*.
+ 1. If _propertyDesc_ has a [[Writable]] field and _propertyDesc_.[[Writable]] is *false*, return *false*.
+ 1. If _propertyDesc_ has a [[Value]] field, perform ? TypedArraySetElement(_obj_, _numericIndex_, _propertyDesc_.[[Value]]).
1. Return *true*.
- 1. Return ! OrdinaryDefineOwnProperty(_O_, _P_, _Desc_).
+ 1. Return ! OrdinaryDefineOwnProperty(_obj_, _propertyKey_, _propertyDesc_).
[[Get]] (
- _P_: a property key,
- _Receiver_: an ECMAScript language value,
+ _propertyKey_: a property key,
+ _receiver_: an ECMAScript language value,
): either a normal completion containing an ECMAScript language value or a throw completion
- for
- - a TypedArray _O_
+ - a TypedArray _obj_
- 1. If _P_ is a String, then
- 1. Let _numericIndex_ be CanonicalNumericIndexString(_P_).
+ 1. If _propertyKey_ is a String, then
+ 1. Let _numericIndex_ be CanonicalNumericIndexString(_propertyKey_).
1. If _numericIndex_ is not *undefined*, then
- 1. Return TypedArrayGetElement(_O_, _numericIndex_).
- 1. Return ? OrdinaryGet(_O_, _P_, _Receiver_).
+ 1. Return TypedArrayGetElement(_obj_, _numericIndex_).
+ 1. Return ? OrdinaryGet(_obj_, _propertyKey_, _receiver_).
[[Set]] (
- _P_: a property key,
- _V_: an ECMAScript language value,
- _Receiver_: an ECMAScript language value,
+ _propertyKey_: a property key,
+ _value_: an ECMAScript language value,
+ _receiver_: an ECMAScript language value,
): either a normal completion containing a Boolean or a throw completion
- for
- - a TypedArray _O_
+ - a TypedArray _obj_
- 1. If _P_ is a String, then
- 1. Let _numericIndex_ be CanonicalNumericIndexString(_P_).
+ 1. If _propertyKey_ is a String, then
+ 1. Let _numericIndex_ be CanonicalNumericIndexString(_propertyKey_).
1. If _numericIndex_ is not *undefined*, then
- 1. If SameValue(_O_, _Receiver_) is *true*, then
- 1. Perform ? TypedArraySetElement(_O_, _numericIndex_, _V_).
+ 1. If SameValue(_obj_, _receiver_) is *true*, then
+ 1. Perform ? TypedArraySetElement(_obj_, _numericIndex_, _value_).
1. Return *true*.
- 1. If IsValidIntegerIndex(_O_, _numericIndex_) is *false*, return *true*.
- 1. Return ? OrdinarySet(_O_, _P_, _V_, _Receiver_).
+ 1. If IsValidIntegerIndex(_obj_, _numericIndex_) is *false*, return *true*.
+ 1. Return ? OrdinarySet(_obj_, _propertyKey_, _value_, _receiver_).
[[Delete]] (
- _P_: a property key,
+ _propertyKey_: a property key,
): a normal completion containing a Boolean
- for
- - a TypedArray _O_
+ - a TypedArray _obj_
- 1. If _P_ is a String, then
- 1. Let _numericIndex_ be CanonicalNumericIndexString(_P_).
+ 1. If _propertyKey_ is a String, then
+ 1. Let _numericIndex_ be CanonicalNumericIndexString(_propertyKey_).
1. If _numericIndex_ is not *undefined*, then
- 1. If IsValidIntegerIndex(_O_, _numericIndex_) is *false*, return *true*; else return *false*.
- 1. Return ! OrdinaryDelete(_O_, _P_).
+ 1. If IsValidIntegerIndex(_obj_, _numericIndex_) is *false*, return *true*.
+ 1. Return *false*.
+ 1. Return ! OrdinaryDelete(_obj_, _propertyKey_).
@@ -14644,40 +15240,42 @@
[[OwnPropertyKeys]] ( ): a normal completion containing a List of property keys
- for
- - a TypedArray _O_
+ - a TypedArray _obj_
- 1. Let _taRecord_ be MakeTypedArrayWithBufferWitnessRecord(_O_, ~seq-cst~).
+ 1. Let _taRecord_ be MakeTypedArrayWithBufferWitnessRecord(_obj_, ~seq-cst~).
1. Let _keys_ be a new empty List.
1. If IsTypedArrayOutOfBounds(_taRecord_) is *false*, then
1. Let _length_ be TypedArrayLength(_taRecord_).
1. For each integer _i_ such that 0 ≤ _i_ < _length_, in ascending order, do
1. Append ! ToString(𝔽(_i_)) to _keys_.
- 1. For each own property key _P_ of _O_ such that _P_ is a String and _P_ is not an integer index, in ascending chronological order of property creation, do
- 1. Append _P_ to _keys_.
- 1. For each own property key _P_ of _O_ such that _P_ is a Symbol, in ascending chronological order of property creation, do
- 1. Append _P_ to _keys_.
+ 1. For each own property key _propertyKey_ of _obj_ such that _propertyKey_ is a String and _propertyKey_ is not an integer index, in ascending chronological order of property creation, do
+ 1. Append _propertyKey_ to _keys_.
+ 1. For each own property key _propertyKey_ of _obj_ such that _propertyKey_ is a Symbol, in ascending chronological order of property creation, do
+ 1. Append _propertyKey_ to _keys_.
1. Return _keys_.
TypedArray With Buffer Witness Records
- An TypedArray With Buffer Witness Record is a Record value used to encapsulate a TypedArray along with a cached byte length of the viewed buffer. It is used to help ensure there is a single shared memory read event of the byte length data block when the viewed buffer is a growable SharedArrayBuffer.
+ An TypedArray With Buffer Witness Record is a Record used to encapsulate a TypedArray along with a cached byte length of the viewed buffer. It is used to help ensure there is a single ReadSharedMemory event of the byte length data block when the viewed buffer is a growable SharedArrayBuffer.
TypedArray With Buffer Witness Records have the fields listed in
-
-
- Field Name
-
-
- Value
-
-
- Meaning
-
-
+
+
+
+ Field Name
+
+
+ Value
+
+
+ Meaning
+
+
+
[[Object]]
@@ -14726,7 +15324,7 @@
TypedArrayCreate (
- _prototype_: an Object,
+ _proto_: an Object,
): a TypedArray
@@ -14735,16 +15333,17 @@
The Symbol Type
The Symbol type is the set of all non-String values that may be used as the key of an Object property (
- Each possible Symbol value is unique and immutable.
- Each Symbol value immutably holds an associated value called [[Description]] that is either *undefined* or a String value.
+ Each Symbol is unique and immutable.
+ Each Symbol has an immutable [[Description]] internal slot whose value is either a String or *undefined*.
Well-Known Symbols
Well-known symbols are built-in Symbol values that are explicitly referenced by algorithms of this specification. They are typically used as the keys of properties whose values serve as extension points of a specification algorithm. Unless otherwise specified, well-known symbols values are shared by all realms (
- Within this specification a well-known symbol is referred to by using a notation of the form @@name, where “name” is one of the values listed in
+ Within this specification a well-known symbol is referred to using the standard intrinsic notation where the intrinsic is one of the values listed in
+ Previous editions of this specification used a notation of the form @@name, where the current edition would use `%Symbol.name%`. In particular, the following names were used: @@asyncIterator, @@hasInstance, @@isConcatSpreadable, @@iterator , @@match, @@matchAll, @@replace, @@search, @@species, @@split, @@toPrimitive, @@toStringTag, and @@unscopables.
+
+
+
+ Specification Name
+
+
+ [[Description]]
+
+
+ Value and Purpose
+
+
+
-
- Specification Name
-
-
- [[Description]]
-
-
- Value and Purpose
-
+
+ %Symbol.asyncDispose%
+
+
+ *"Symbol.asyncDispose"*
+
+
+ A method that asynchronously performs resource cleanup on an object. Called by AsyncDisposableStack objects and `await using` declarations when evaluation of their containing scope completes.
+
- @@asyncIterator
+ %Symbol.asyncIterator%
*"Symbol.asyncIterator"*
- A method that returns the default AsyncIterator for an object. Called by the semantics of the `for`-`await`-`of` statement.
+ A method that returns the default async iterator for an object. Called by the semantics of the `for`-`await`-`of` statement.
- @@hasInstance
+ %Symbol.dispose%
+
+
+ *"Symbol.dispose"*
+
+
+ A method that performs explicit resource cleanup on an object. Called by DisposableStack objects, AsyncDisposableStack objects, and `using` declarations when evaluation of their containing scope completes.
+
+
+
+
+ %Symbol.hasInstance%
*"Symbol.hasInstance"*
@@ -1245,7 +1379,7 @@ Well-Known Symbols
- @@isConcatSpreadable
+ %Symbol.isConcatSpreadable%
*"Symbol.isConcatSpreadable"*
@@ -1256,18 +1390,18 @@ Well-Known Symbols
- @@iterator
+ %Symbol.iterator%
*"Symbol.iterator"*
- A method that returns the default Iterator for an object. Called by the semantics of the for-of statement.
+ A method that returns the default iterator for an object. Called by the semantics of the for-of statement.
- @@match
+ %Symbol.match%
*"Symbol.match"*
@@ -1278,18 +1412,18 @@ Well-Known Symbols
- @@matchAll
+ %Symbol.matchAll%
*"Symbol.matchAll"*
- A regular expression method that returns an iterator, that yields matches of the regular expression against a string. Called by the `String.prototype.matchAll` method.
+ A regular expression method that returns an iterator that yields matches of the regular expression against a string. Called by the `String.prototype.matchAll` method.
- @@replace
+ %Symbol.replace%
*"Symbol.replace"*
@@ -1300,7 +1434,7 @@ Well-Known Symbols
- @@search
+ %Symbol.search%
*"Symbol.search"*
@@ -1311,7 +1445,7 @@ Well-Known Symbols
- @@species
+ %Symbol.species%
*"Symbol.species"*
@@ -1322,7 +1456,7 @@ Well-Known Symbols
- @@split
+ %Symbol.split%
*"Symbol.split"*
@@ -1333,7 +1467,7 @@ Well-Known Symbols
- @@toPrimitive
+ %Symbol.toPrimitive%
*"Symbol.toPrimitive"*
@@ -1344,7 +1478,7 @@ Well-Known Symbols
- @@toStringTag
+ %Symbol.toStringTag%
*"Symbol.toStringTag"*
@@ -1355,7 +1489,7 @@ Well-Known Symbols
- @@unscopables
+ %Symbol.unscopables%
*"Symbol.unscopables"*
@@ -1371,23 +1505,25 @@ Well-Known Symbols
Numeric Types
- ECMAScript has two built-in numeric types: Number and BigInt. The following abstract operations are defined over these numeric types. The "Result" column shows the return type, along with an indication if it is possible for some invocations of the operation to return an abrupt completion.
+ ECMAScript has two built-in numeric types: Number and BigInt. The following abstract operations are defined over these numeric types. The “Result” column shows the return type, along with an indication if it is possible for some invocations of the operation to return an abrupt completion.
-
-
- Operation
-
-
- Example source
-
-
- Invoked by the Evaluation semantics of ...
-
-
- Result
-
-
+
+
+
+ Operation
+
+
+ Example source
+
+
+ Invoked by the Evaluation semantics of ...
+
+
+ Result
+
+
+
@@ -1728,9 +1864,8 @@ Numeric Types
`[x].includes(y)`
- Array, Map, and Set methods,
via
Boolean
@@ -1828,7 +1963,7 @@ Numeric Types
The Number Type
- The Number type has exactly 18,437,736,874,454,810,627 (that is, 264 - 253 + 3 ) values, representing the double-precision floating point IEEE 754-2019 binary64 values as specified in the IEEE Standard for Binary Floating-Point Arithmetic, except that the 9,007,199,254,740,990 (that is, 253 - 2 ) distinct “Not-a-Number” values of the IEEE Standard are represented in ECMAScript as a single special *NaN* value. (Note that the *NaN* value is produced by the program expression `NaN`.) In some implementations, external code might be able to detect a difference between various Not-a-Number values, but such behaviour is implementation-defined; to ECMAScript code, all *NaN* values are indistinguishable from each other.
+ The Number type has exactly 18,437,736,874,454,810,627 (that is, 264 - 253 + 3 ) values, representing the double-precision floating point IEEE 754-2019 binary64 values as specified in the IEEE Standard for Binary Floating-Point Arithmetic, except that the 9,007,199,254,740,990 (that is, 253 - 2 ) distinct NaN values of the IEEE Standard are represented in ECMAScript as a single special *NaN* value. (Note that the *NaN* value is produced by the program expression `NaN`.) In some implementations, external code might be able to detect a difference between various NaN values, but such behaviour is implementation-defined; to ECMAScript code, all *NaN* values are indistinguishable from each other.
The bit pattern that might be observed in an ArrayBuffer (see
@@ -1855,28 +1990,28 @@ The Number Type
Number::unaryMinus (
- _x_: a Number,
+ _number_: a Number,
): a Number
- 1. If _x_ is *NaN*, return *NaN*.
- 1. Return the result of negating _x_; that is, compute a Number with the same magnitude but opposite sign.
+ 1. If _number_ is *NaN*, return *NaN*.
+ 1. Return the negation of _number_; that is, compute a Number with the same magnitude but opposite sign.
Number::bitwiseNOT (
- _x_: a Number,
+ _number_: a Number,
): an integral Number
- 1. Let _oldValue_ be ! ToInt32(_x_).
- 1. Return the result of applying bitwise complement to _oldValue_. The mathematical value of the result is exactly representable as a 32-bit two's complement bit string.
+ 1. Let _oldValue_ be ! ToInt32(_number_).
+ 1. Return the bitwise complement of _oldValue_. The mathematical value of the result is exactly representable as a 32-bit two's complement bit string.
@@ -1896,28 +2031,32 @@
1. If _exponent_ is either *+0*𝔽 or *-0*𝔽, return *1*𝔽.
1. If _base_ is *NaN*, return *NaN*.
1. If _base_ is *+∞*𝔽, then
- 1. If _exponent_ > *+0*𝔽, return *+∞*𝔽. Otherwise, return *+0*𝔽.
+ 1. If _exponent_ > *+0*𝔽, return *+∞*𝔽.
+ 1. Return *+0*𝔽.
1. If _base_ is *-∞*𝔽, then
1. If _exponent_ > *+0*𝔽, then
- 1. If _exponent_ is an odd integral Number, return *-∞*𝔽. Otherwise, return *+∞*𝔽.
- 1. Else,
- 1. If _exponent_ is an odd integral Number, return *-0*𝔽. Otherwise, return *+0*𝔽.
+ 1. If _exponent_ is an odd integral Number, return *-∞*𝔽.
+ 1. Return *+∞*𝔽.
+ 1. If _exponent_ is an odd integral Number, return *-0*𝔽.
+ 1. Return *+0*𝔽.
1. If _base_ is *+0*𝔽, then
- 1. If _exponent_ > *+0*𝔽, return *+0*𝔽. Otherwise, return *+∞*𝔽.
+ 1. If _exponent_ > *+0*𝔽, return *+0*𝔽.
+ 1. Return *+∞*𝔽.
1. If _base_ is *-0*𝔽, then
1. If _exponent_ > *+0*𝔽, then
- 1. If _exponent_ is an odd integral Number, return *-0*𝔽. Otherwise, return *+0*𝔽.
- 1. Else,
- 1. If _exponent_ is an odd integral Number, return *-∞*𝔽. Otherwise, return *+∞*𝔽.
+ 1. If _exponent_ is an odd integral Number, return *-0*𝔽.
+ 1. Return *+0*𝔽.
+ 1. If _exponent_ is an odd integral Number, return *-∞*𝔽.
+ 1. Return *+∞*𝔽.
1. Assert: _base_ is finite and is neither *+0*𝔽 nor *-0*𝔽.
1. If _exponent_ is *+∞*𝔽, then
1. If abs(ℝ(_base_)) > 1, return *+∞*𝔽.
1. If abs(ℝ(_base_)) = 1, return *NaN*.
- 1. If abs(ℝ(_base_)) < 1, return *+0*𝔽.
+ 1. Return *+0*𝔽.
1. If _exponent_ is *-∞*𝔽, then
1. If abs(ℝ(_base_)) > 1, return *+0*𝔽.
1. If abs(ℝ(_base_)) = 1, return *NaN*.
- 1. If abs(ℝ(_base_)) < 1, return *+∞*𝔽.
+ 1. Return *+∞*𝔽.
1. Assert: _exponent_ is finite and is neither *+0*𝔽 nor *-0*𝔽.
1. If _base_ < *-0*𝔽 and _exponent_ is not an integral Number, return *NaN*.
1. Return an implementation-approximated Number value representing the result of raising ℝ(_base_) to the ℝ(_exponent_) power.
@@ -1950,10 +2089,10 @@
1. Return -_y_.
1. If _x_ is *-0*𝔽, then
1. If _y_ is *-0*𝔽 or _y_ < *-0*𝔽, return *+0*𝔽.
- 1. Else, return *-0*𝔽.
+ 1. Return *-0*𝔽.
1. If _y_ is *-0*𝔽, then
1. If _x_ < *-0*𝔽, return *+0*𝔽.
- 1. Else, return *-0*𝔽.
+ 1. Return *-0*𝔽.
1. Return 𝔽(ℝ(_x_) × ℝ(_y_)).
@@ -1979,17 +2118,21 @@
1. If _y_ is *+0*𝔽 or _y_ > *+0*𝔽, return _x_.
1. Return -_x_.
1. If _y_ is *+∞*𝔽, then
- 1. If _x_ is *+0*𝔽 or _x_ > *+0*𝔽, return *+0*𝔽. Otherwise, return *-0*𝔽.
+ 1. If _x_ is *+0*𝔽 or _x_ > *+0*𝔽, return *+0*𝔽.
+ 1. Return *-0*𝔽.
1. If _y_ is *-∞*𝔽, then
- 1. If _x_ is *+0*𝔽 or _x_ > *+0*𝔽, return *-0*𝔽. Otherwise, return *+0*𝔽.
+ 1. If _x_ is *+0*𝔽 or _x_ > *+0*𝔽, return *-0*𝔽.
+ 1. Return *+0*𝔽.
1. If _x_ is either *+0*𝔽 or *-0*𝔽, then
1. If _y_ is either *+0*𝔽 or *-0*𝔽, return *NaN*.
1. If _y_ > *+0*𝔽, return _x_.
1. Return -_x_.
1. If _y_ is *+0*𝔽, then
- 1. If _x_ > *+0*𝔽, return *+∞*𝔽. Otherwise, return *-∞*𝔽.
+ 1. If _x_ > *+0*𝔽, return *+∞*𝔽.
+ 1. Return *-∞*𝔽.
1. If _y_ is *-0*𝔽, then
- 1. If _x_ > *+0*𝔽, return *-∞*𝔽. Otherwise, return *+∞*𝔽.
+ 1. If _x_ > *+0*𝔽, return *-∞*𝔽.
+ 1. Return *+∞*𝔽.
1. Return 𝔽(ℝ(_x_) / ℝ(_y_)).
@@ -1997,26 +2140,26 @@
Number::remainder (
- _n_: a Number,
- _d_: a Number,
+ _numerator_: a Number,
+ _denominator_: a Number,
): a Number
- description
- - It yields the remainder from an implied division of its operands where _n_ is the dividend and _d_ is the divisor.
+ - It yields the remainder from an implied division of its operands where _numerator_ is the dividend and _denominator_ is the divisor.
- 1. If _n_ is *NaN* or _d_ is *NaN*, return *NaN*.
- 1. If _n_ is either *+∞*𝔽 or *-∞*𝔽, return *NaN*.
- 1. If _d_ is either *+∞*𝔽 or *-∞*𝔽, return _n_.
- 1. If _d_ is either *+0*𝔽 or *-0*𝔽, return *NaN*.
- 1. If _n_ is either *+0*𝔽 or *-0*𝔽, return _n_.
- 1. Assert: _n_ and _d_ are finite and non-zero.
- 1. Let _quotient_ be ℝ(_n_) / ℝ(_d_).
- 1. Let _q_ be truncate(_quotient_).
- 1. Let _r_ be ℝ(_n_) - (ℝ(_d_) × _q_).
- 1. If _r_ = 0 and _n_ < *-0*𝔽, return *-0*𝔽.
- 1. Return 𝔽(_r_).
+ 1. If _numerator_ is *NaN* or _denominator_ is *NaN*, return *NaN*.
+ 1. If _numerator_ is either *+∞*𝔽 or *-∞*𝔽, return *NaN*.
+ 1. If _denominator_ is either *+∞*𝔽 or *-∞*𝔽, return _numerator_.
+ 1. If _denominator_ is either *+0*𝔽 or *-0*𝔽, return *NaN*.
+ 1. If _numerator_ is either *+0*𝔽 or *-0*𝔽, return _numerator_.
+ 1. Assert: _numerator_ and _denominator_ are finite and non-zero.
+ 1. Let _quotient_ be ℝ(_numerator_) / ℝ(_denominator_).
+ 1. Let _truncatedQuotient_ be truncate(_quotient_).
+ 1. Let _remainder_ be ℝ(_numerator_) - (ℝ(_denominator_) × _truncatedQuotient_).
+ 1. If _remainder_ = 0 and _numerator_ < *-0*𝔽, return *-0*𝔽.
+ 1. Return 𝔽(_remainder_).
In C and C++, the remainder operator accepts only integral operands; in ECMAScript, it also accepts floating-point operands.
@@ -2079,10 +2222,10 @@
- 1. Let _lnum_ be ! ToInt32(_x_).
- 1. Let _rnum_ be ! ToUint32(_y_).
- 1. Let _shiftCount_ be ℝ(_rnum_) modulo 32.
- 1. Return the result of left shifting _lnum_ by _shiftCount_ bits. The mathematical value of the result is exactly representable as a 32-bit two's complement bit string.
+ 1. Let _leftNumber_ be ! ToInt32(_x_).
+ 1. Let _rightNumber_ be ! ToUint32(_y_).
+ 1. Let _shiftCount_ be ℝ(_rightNumber_) modulo 32.
+ 1. Return the result of left shifting _leftNumber_ by _shiftCount_ bits. The mathematical value of the result is exactly representable as a 32-bit two's complement bit string.
@@ -2096,10 +2239,10 @@
- 1. Let _lnum_ be ! ToInt32(_x_).
- 1. Let _rnum_ be ! ToUint32(_y_).
- 1. Let _shiftCount_ be ℝ(_rnum_) modulo 32.
- 1. Return the result of performing a sign-extending right shift of _lnum_ by _shiftCount_ bits. The most significant bit is propagated. The mathematical value of the result is exactly representable as a 32-bit two's complement bit string.
+ 1. Let _leftNumber_ be ! ToInt32(_x_).
+ 1. Let _rightNumber_ be ! ToUint32(_y_).
+ 1. Let _shiftCount_ be ℝ(_rightNumber_) modulo 32.
+ 1. Return the result of performing a sign-extending right shift of _leftNumber_ by _shiftCount_ bits. The most significant bit is propagated. The mathematical value of the result is exactly representable as a 32-bit two's complement bit string.
@@ -2113,10 +2256,10 @@
- 1. Let _lnum_ be ! ToUint32(_x_).
- 1. Let _rnum_ be ! ToUint32(_y_).
- 1. Let _shiftCount_ be ℝ(_rnum_) modulo 32.
- 1. Return the result of performing a zero-filling right shift of _lnum_ by _shiftCount_ bits. Vacated bits are filled with zero. The mathematical value of the result is exactly representable as a 32-bit unsigned bit string.
+ 1. Let _leftNumber_ be ! ToUint32(_x_).
+ 1. Let _rightNumber_ be ! ToUint32(_y_).
+ 1. Let _shiftCount_ be ℝ(_rightNumber_) modulo 32.
+ 1. Return the result of performing a zero-filling right shift of _leftNumber_ by _shiftCount_ bits. Vacated bits are filled with zero. The mathematical value of the result is exactly representable as a 32-bit unsigned bit string.
@@ -2140,7 +2283,8 @@
1. If _y_ is *-∞*𝔽, return *false*.
1. If _x_ is *-∞*𝔽, return *true*.
1. Assert: _x_ and _y_ are finite.
- 1. If ℝ(_x_) < ℝ(_y_), return *true*. Otherwise, return *false*.
+ 1. If ℝ(_x_) < ℝ(_y_), return *true*.
+ 1. Return *false*.
@@ -2210,17 +2354,17 @@
- 1. Let _lnum_ be ! ToInt32(_x_).
- 1. Let _rnum_ be ! ToInt32(_y_).
- 1. Let _lbits_ be the 32-bit two's complement bit string representing ℝ(_lnum_).
- 1. Let _rbits_ be the 32-bit two's complement bit string representing ℝ(_rnum_).
+ 1. Let _leftNumber_ be ! ToInt32(_x_).
+ 1. Let _rightNumber_ be ! ToInt32(_y_).
+ 1. Let _leftBits_ be the 32-bit two's complement bit string representing ℝ(_leftNumber_).
+ 1. Let _rightBits_ be the 32-bit two's complement bit string representing ℝ(_rightNumber_).
1. If _op_ is `&`, then
- 1. Let _result_ be the result of applying the bitwise AND operation to _lbits_ and _rbits_.
+ 1. Let _result_ be the result of applying the bitwise AND operation to _leftBits_ and _rightBits_.
1. Else if _op_ is `^`, then
- 1. Let _result_ be the result of applying the bitwise exclusive OR (XOR) operation to _lbits_ and _rbits_.
+ 1. Let _result_ be the result of applying the bitwise exclusive OR (XOR) operation to _leftBits_ and _rightBits_.
1. Else,
1. Assert: _op_ is `|`.
- 1. Let _result_ be the result of applying the bitwise inclusive OR operation to _lbits_ and _rbits_.
+ 1. Let _result_ be the result of applying the bitwise inclusive OR operation to _leftBits_ and _rightBits_.
1. Return the Number value for the integer represented by the 32-bit two's complement bit string _result_.
@@ -2289,18 +2433,17 @@
1. Return the string-concatenation of:
* the code units of the _k_ digits of the representation of _s_ using radix _radix_
* _n_ - _k_ occurrences of the code unit 0x0030 (DIGIT ZERO)
- 1. Else if _n_ > 0, then
+ 1. If _n_ > 0, then
1. Return the string-concatenation of:
* the code units of the most significant _n_ digits of the representation of _s_ using radix _radix_
* the code unit 0x002E (FULL STOP)
* the code units of the remaining _k_ - _n_ digits of the representation of _s_ using radix _radix_
- 1. Else,
- 1. Assert: _n_ ≤ 0.
- 1. Return the string-concatenation of:
- * the code unit 0x0030 (DIGIT ZERO)
- * the code unit 0x002E (FULL STOP)
- * -_n_ occurrences of the code unit 0x0030 (DIGIT ZERO)
- * the code units of the _k_ digits of the representation of _s_ using radix _radix_
+ 1. Assert: _n_ ≤ 0.
+ 1. Return the string-concatenation of:
+ * the code unit 0x0030 (DIGIT ZERO)
+ * the code unit 0x002E (FULL STOP)
+ * -_n_ occurrences of the code unit 0x0030 (DIGIT ZERO)
+ * the code units of the _k_ digits of the representation of _s_ using radix _radix_
1. NOTE: In this case, the input will be represented using scientific E notation, such as `1.2e+3`.
1. Assert: _radix_ is 10.
1. If _n_ < 0, then
@@ -2335,14 +2478,14 @@
For implementations that provide more accurate conversions than required by the rules above, it is recommended that the following alternative version of step
- 1. Let _n_, _k_, and _s_ be integers such that _k_ ≥ 1, _radix__k_ - 1 ≤ _s_ < _radix__k_, 𝔽(_s_ × _radix__n_ - _k_) is _x_, and _k_ is as small as possible. If there are multiple possibilities for _s_, choose the value of _s_ for which _s_ × _radix__n_ - _k_ is closest in value to ℝ(_x_). If there are two such possible values of _s_, choose the one that is even. Note that _k_ is the number of digits in the representation of _s_ using radix _radix_ and that _s_ is not divisible by _radix_.
+ 1. Let _n_, _k_, and _s_ be integers such that _k_ ≥ 1, _radix__k_ - 1 ≤ _s_ < _radix__k_, 𝔽(_s_ × _radix__n_ - _k_) is _x_, and _k_ is as small as possible. If there are multiple possibilities for _s_, choose _s_ such that _s_ × _radix__n_ - _k_ is closest to ℝ(_x_). If there are two such possible values of _s_, choose the one that is even. Note that _k_ is the number of digits in the representation of _s_ using radix _radix_ and that _s_ is not divisible by _radix_.
Implementers of ECMAScript may find useful the paper and code written by David M. Gay for binary-to-decimal conversion of floating-point numbers:
Gay, David M. Correctly Rounded Binary-Decimal and Decimal-Binary Conversions. Numerical Analysis, Manuscript 90-10. AT&T Bell Laboratories (Murray Hill, New Jersey). 30 November 1990. Available as
- http://ampl.com/REFS/abstracts.html#rounding. Associated code available as
+ https://ampl.com/_archive/first-website/REFS/rounding.pdf. Associated code available as
http://netlib.sandia.gov/fp/dtoa.c and as
http://netlib.sandia.gov/fp/g_fmt.c and may also be found at the various `netlib` mirror sites.
@@ -2357,29 +2500,29 @@ The BigInt Type
BigInt::unaryMinus (
- _x_: a BigInt,
+ _bigint_: a BigInt,
): a BigInt
- 1. If _x_ = *0*ℤ, return *0*ℤ.
- 1. Return -_x_.
+ 1. If _bigint_ = *0*ℤ, return *0*ℤ.
+ 1. Return -_bigint_.
BigInt::bitwiseNOT (
- _x_: a BigInt,
+ _bigint_: a BigInt,
): a BigInt
- description
- - It returns the one's complement of _x_.
+ - It returns the one's complement of _bigint_.
- 1. Return -_x_ - *1*ℤ.
+ 1. Return -_bigint_ - *1*ℤ.
@@ -2433,18 +2576,18 @@
BigInt::remainder (
- _n_: a BigInt,
- _d_: a BigInt,
+ _numerator_: a BigInt,
+ _denominator_: a BigInt,
): either a normal completion containing a BigInt or a throw completion
- 1. If _d_ = *0*ℤ, throw a *RangeError* exception.
- 1. If _n_ = *0*ℤ, return *0*ℤ.
- 1. Let _quotient_ be ℝ(_n_) / ℝ(_d_).
- 1. Let _q_ be ℤ(truncate(_quotient_)).
- 1. Return _n_ - (_d_ × _q_).
+ 1. If _denominator_ = *0*ℤ, throw a *RangeError* exception.
+ 1. If _numerator_ = *0*ℤ, return *0*ℤ.
+ 1. Let _quotient_ be ℝ(_numerator_) / ℝ(_denominator_).
+ 1. Let _truncatedQuotient_ be ℤ(truncate(_quotient_)).
+ 1. Return _numerator_ - (_denominator_ × _truncatedQuotient_).
The sign of the result is the sign of the dividend.
@@ -2532,7 +2675,8 @@
- 1. If ℝ(_x_) < ℝ(_y_), return *true*; otherwise return *false*.
+ 1. If ℝ(_x_) < ℝ(_y_), return *true*.
+ 1. Return *false*.
@@ -2546,7 +2690,8 @@
- 1. If ℝ(_x_) = ℝ(_y_), return *true*; otherwise return *false*.
+ 1. If ℝ(_x_) = ℝ(_y_), return *true*.
+ 1. Return *false*.
@@ -2561,7 +2706,7 @@
1. If _x_ = 1 and _y_ = 1, return 1.
- 1. Else, return 0.
+ 1. Return 0.
@@ -2576,7 +2721,7 @@
1. If _x_ = 1 or _y_ = 1, return 1.
- 1. Else, return 0.
+ 1. Return 0.
@@ -2591,8 +2736,8 @@
1. If _x_ = 1 and _y_ = 0, return 1.
- 1. Else if _x_ = 0 and _y_ = 1, return 1.
- 1. Else, return 0.
+ 1. If _x_ = 0 and _y_ = 1, return 1.
+ 1. Return 0.
@@ -2625,13 +2770,13 @@
1. Set _x_ to (_x_ - _xDigit_) / 2.
1. Set _y_ to (_y_ - _yDigit_) / 2.
1. If _op_ is `&`, then
- 1. Let _tmp_ be BinaryAnd(_x_ modulo 2, _y_ modulo 2).
+ 1. Let _signBit_ be BinaryAnd(_x_ modulo 2, _y_ modulo 2).
1. Else if _op_ is `|`, then
- 1. Let _tmp_ be BinaryOr(_x_ modulo 2, _y_ modulo 2).
+ 1. Let _signBit_ be BinaryOr(_x_ modulo 2, _y_ modulo 2).
1. Else,
1. Assert: _op_ is `^`.
- 1. Let _tmp_ be BinaryXor(_x_ modulo 2, _y_ modulo 2).
- 1. If _tmp_ ≠ 0, then
+ 1. Let _signBit_ be BinaryXor(_x_ modulo 2, _y_ modulo 2).
+ 1. If _signBit_ ≠ 0, then
1. Set _result_ to _result_ - 2_shift_.
1. NOTE: This extends the sign.
1. Return the BigInt value for _result_.
@@ -2710,7 +2855,7 @@ The Object Type
An accessor property associates a key value with one or two accessor functions, and a set of Boolean attributes. The accessor functions are used to store or retrieve an ECMAScript language value that is associated with the property.
-
The properties of an object are uniquely identified using property keys. A property key is either a String or a Symbol. All Strings and Symbols, including the empty String, are valid as property keys. A property name is a property key that is a String.
+ The properties of an object are uniquely identified using property keys. A property key is either a String or a Symbol. All Strings and Symbols, including the empty String, are valid as property keys. A property name is a property key that is a String.
An integer index is a property name _n_ such that CanonicalNumericIndexString(_n_) returns an integral Number in the inclusive interval from *+0*𝔽 to 𝔽(253 - 1). An array index is an integer index _n_ such that CanonicalNumericIndexString(_n_) returns an integral Number in the inclusive interval from *+0*𝔽 to 𝔽(232 - 2).
Every non-negative safe integer has a corresponding integer index. Every 32-bit unsigned integer except 232 - 1 has a corresponding array index. *"-0"* is neither an integer index nor an array index.
@@ -2724,13 +2869,15 @@ Property Attributes
Attributes are used in this specification to define and explain the state of Object properties as described in
-
- Attribute Name
- Types of property for which it is present
- Value Domain
- Default Value
- Description
-
+
+
+ Attribute Name
+ Types of property for which it is present
+ Value Domain
+ Default Value
+ Description
+
+
[[Value]]
@@ -2767,36 +2914,36 @@ Property Attributes
- [[Get]]
+ [[Getter]]
accessor property
- an Object or *undefined*
+ a function object or *undefined*
*undefined*
- If the value is an Object it must be a function object. The function's [[Call]] internal method (
- [[Set]]
+ [[Setter]]
accessor property
- an Object or *undefined*
+ a function object or *undefined*
*undefined*
- If the value is an Object it must be a function object. The function's [[Call]] internal method (
@@ -2841,7 +2988,7 @@ Property Attributes
Object Internal Methods and Internal Slots
The actual semantics of objects, in ECMAScript, are specified via algorithms called internal methods. Each object in an ECMAScript engine is associated with a set of internal methods that defines its runtime behaviour. These internal methods are not part of the ECMAScript language. They are defined by this specification purely for expository purposes. However, each object within an implementation of ECMAScript must behave as specified by the internal methods associated with it. The exact manner in which this is accomplished is determined by the implementation.
Internal method names are polymorphic. This means that different object values may perform different algorithms when a common internal method name is invoked upon them. That actual object upon which an internal method is invoked is the “target” of the invocation. If, at runtime, the implementation of an algorithm attempts to use an internal method of an object that the object does not support, a *TypeError* exception is thrown.
- Internal slots correspond to internal state that is associated with objects and used by various ECMAScript specification algorithms. Internal slots are not object properties and they are not inherited. Depending upon the specific internal slot specification, such state may consist of values of any ECMAScript language type or of specific ECMAScript specification type values. Unless explicitly specified otherwise, internal slots are allocated as part of the process of creating an object and may not be dynamically added to an object. Unless specified otherwise, the initial value of an internal slot is the value *undefined*. Various algorithms within this specification create objects that have internal slots. However, the ECMAScript language provides no direct way to associate internal slots with an object.
+ Internal slots correspond to internal state that is associated with objects, Symbols, or Private Names and used by various ECMAScript specification algorithms. Internal slots are not object properties and they are not inherited. Depending upon the specific internal slot specification, such state may consist of values of any ECMAScript language type or of specific ECMAScript specification type values. Unless explicitly specified otherwise, internal slots are allocated as part of the process of creating an object, Symbol, or Private Name and may not be dynamically added. Unless specified otherwise, the initial value of an internal slot is the value *undefined*. Various algorithms within this specification create values that have internal slots. However, the ECMAScript language provides no direct way to manipulate internal slots.
All objects have an internal slot named [[PrivateElements]], which is a List of PrivateElements. This List represents the values of the private fields, methods, and accessors for the object. Initially, it is an empty List.
Internal methods and internal slots are identified within this specification using names enclosed in double square brackets [[ ]].
@@ -2864,17 +3011,19 @@ Object Internal Methods and Internal Slots
An internal method implicitly returns a Completion Record, either a normal completion that wraps a value of the return type shown in its invocation pattern, or a throw completion.
-
-
- Internal Method
-
-
- Signature
-
-
- Description
-
-
+
+
+
+ Internal Method
+
+
+ Signature
+
+
+ Description
+
+
+
[[GetPrototypeOf]]
@@ -2935,10 +3084,10 @@ Object Internal Methods and Internal Slots
[[DefineOwnProperty]]
- (_propertyKey_, _PropertyDescriptor_) → Boolean
+ (_propertyKey_, _propertyDesc_) → Boolean
- Create or alter the own property, whose key is _propertyKey_, to have the state described by _PropertyDescriptor_. Return *true* if that property was successfully created/updated or *false* if the property could not be created or updated.
+ Create or alter the own property, whose key is _propertyKey_, to have the state described by _propertyDesc_. Return *true* if that property was successfully created/updated or *false* if the property could not be created or updated.
@@ -2957,10 +3106,10 @@ Object Internal Methods and Internal Slots
[[Get]]
- (_propertyKey_, _Receiver_) → any
+ (_propertyKey_, _receiver_) → any
- Return the value of the property whose key is _propertyKey_ from this object. If any ECMAScript code must be executed to retrieve the property value, _Receiver_ is used as the *this* value when evaluating the code.
+ Return the value of the property whose key is _propertyKey_ from this object. If any ECMAScript code must be executed to retrieve the property value, _receiver_ is used as the *this* value when evaluating the code.
@@ -2968,10 +3117,10 @@ Object Internal Methods and Internal Slots
[[Set]]
- (_propertyKey_, _value_, _Receiver_) → Boolean
+ (_propertyKey_, _value_, _receiver_) → Boolean
- Set the value of the property whose key is _propertyKey_ to _value_. If any ECMAScript code must be executed to set the property value, _Receiver_ is used as the *this* value when evaluating the code. Returns *true* if the property value was set or *false* if it could not be set.
+ Set the value of the property whose key is _propertyKey_ to _value_. If any ECMAScript code must be executed to set the property value, _receiver_ is used as the *this* value when evaluating the code. Returns *true* if the property value was set or *false* if it could not be set.
@@ -3001,17 +3150,19 @@ Object Internal Methods and Internal Slots
-
-
- Internal Method
-
-
- Signature
-
-
- Description
-
-
+
+
+
+ Internal Method
+
+
+ Signature
+
+
+ Description
+
+
+
[[Call]]
@@ -3062,7 +3213,7 @@ Definitions:
Return value:
The value returned by any internal method must be a Completion Record with either:
- - [[Type]] = ~normal~, [[Target]] = ~empty~, and [[Value]] = a value of the "normal return type" shown below for that internal method, or
+ - [[Type]] = ~normal~, [[Target]] = ~empty~, and [[Value]] = a value of the “normal return type” shown below for that internal method, or
- [[Type]] = ~throw~, [[Target]] = ~empty~, and [[Value]] = any ECMAScript language value.
@@ -3074,19 +3225,19 @@ [[GetPrototypeOf]] ( )
The normal return type is either Object or Null.
- If target is non-extensible, and [[GetPrototypeOf]] returns a value _V_, then any future calls to [[GetPrototypeOf]] should return the SameValue as _V_.
+ If target is non-extensible, and [[GetPrototypeOf]] returns a value _proto_, then any future calls to [[GetPrototypeOf]] should return the SameValue as _proto_.
An object's prototype chain should have finite length (that is, starting from any object, recursively applying the [[GetPrototypeOf]] internal method to its result should eventually lead to the value *null*). However, this requirement is not enforceable as an object level invariant if the prototype chain includes any exotic objects that do not use the ordinary object definition of [[GetPrototypeOf]]. Such a circular prototype chain may result in infinite loops when accessing object properties.
- [[SetPrototypeOf]] ( _V_ )
+ [[SetPrototypeOf]] ( _proto_ )
-
The normal return type is Boolean.
-
- If target is non-extensible, [[SetPrototypeOf]] must return *false*, unless _V_ is the SameValue as the target's observed [[GetPrototypeOf]] value.
+ If target is non-extensible, [[SetPrototypeOf]] must return *false*, unless _proto_ is the SameValue as the target's observed [[GetPrototypeOf]] value.
[[IsExtensible]] ( )
@@ -3107,90 +3258,90 @@ [[PreventExtensions]] ( )
If [[PreventExtensions]] returns *true*, all future calls to [[IsExtensible]] on the target must return *false* and the target is now considered non-extensible.
- [[GetOwnProperty]] ( _P_ )
+ [[GetOwnProperty]] ( _propertyKey_ )
-
The normal return type is either Property Descriptor or Undefined.
-
- If the Type of the return value is Property Descriptor, the return value must be a fully populated Property Descriptor.
+ If the return value is a Property Descriptor, it must be a fully populated Property Descriptor.
-
- If _P_ is described as a non-configurable, non-writable own data property, all future calls to [[GetOwnProperty]] ( _P_ ) must return Property Descriptor whose [[Value]] is SameValue as _P_'s [[Value]] attribute.
+ If _propertyKey_ is described as a non-configurable, non-writable own data property, all future calls to [[GetOwnProperty]] ( _propertyKey_ ) must return Property Descriptor whose [[Value]] is SameValue as _propertyKey_'s [[Value]] attribute.
-
- If _P_'s attributes other than [[Writable]] and [[Value]] may change over time, or if the property might be deleted, then _P_'s [[Configurable]] attribute must be *true*.
+ If _propertyKey_'s attributes other than [[Writable]] and [[Value]] may change over time, or if the property might be deleted, then _propertyKey_'s [[Configurable]] attribute must be *true*.
-
If the [[Writable]] attribute may change from *false* to *true*, then the [[Configurable]] attribute must be *true*.
-
- If the target is non-extensible and _P_ is non-existent, then all future calls to [[GetOwnProperty]] (_P_) on the target must describe _P_ as non-existent (i.e. [[GetOwnProperty]] (_P_) must return *undefined*).
+ If the target is non-extensible and _propertyKey_ is non-existent, then all future calls to [[GetOwnProperty]] (_propertyKey_) on the target must describe _propertyKey_ as non-existent (i.e. [[GetOwnProperty]] (_propertyKey_) must return *undefined*).
As a consequence of the third invariant, if a property is described as a data property and it may return different values over time, then either or both of the [[Writable]] and [[Configurable]] attributes must be *true* even if no mechanism to change the value is exposed via the other essential internal methods.
- [[DefineOwnProperty]] ( _P_, _Desc_ )
+ [[DefineOwnProperty]] ( _propertyKey_, _propertyDesc_ )
-
The normal return type is Boolean.
-
- [[DefineOwnProperty]] must return *false* if _P_ has previously been observed as a non-configurable own property of the target, unless either:
+ [[DefineOwnProperty]] must return *false* if _propertyKey_ has previously been observed as a non-configurable own property of the target, unless either:
-
- _P_ is a writable data property. A non-configurable writable data property can be changed into a non-configurable non-writable data property.
+ _propertyKey_ is a writable data property. A non-configurable writable data property can be changed into a non-configurable non-writable data property.
-
- All attributes of _Desc_ are the SameValue as _P_'s attributes.
+ All attributes of _propertyDesc_ are the SameValue as _propertyKey_'s attributes.
-
- [[DefineOwnProperty]] (_P_, _Desc_) must return *false* if target is non-extensible and _P_ is a non-existent own property. That is, a non-extensible target object cannot be extended with new properties.
+ [[DefineOwnProperty]] (_propertyKey_, _propertyDesc_) must return *false* if target is non-extensible and _propertyKey_ is a non-existent own property. That is, a non-extensible target object cannot be extended with new properties.
- [[HasProperty]] ( _P_ )
+ [[HasProperty]] ( _propertyKey_ )
-
The normal return type is Boolean.
-
- If _P_ was previously observed as a non-configurable own data or accessor property of the target, [[HasProperty]] must return *true*.
+ If _propertyKey_ was previously observed as a non-configurable own data or accessor property of the target, [[HasProperty]] must return *true*.
- [[Get]] ( _P_, _Receiver_ )
+ [[Get]] ( _propertyKey_, _receiver_ )
-
The normal return type is any ECMAScript language type.
-
- If _P_ was previously observed as a non-configurable, non-writable own data property of the target with value _V_, then [[Get]] must return the SameValue as _V_.
+ If _propertyKey_ was previously observed as a non-configurable, non-writable own data property of the target with value _value_, then [[Get]] must return the SameValue as _value_.
-
- If _P_ was previously observed as a non-configurable own accessor property of the target whose [[Get]] attribute is *undefined*, the [[Get]] operation must return *undefined*.
+ If _propertyKey_ was previously observed as a non-configurable own accessor property of the target whose [[Getter]] attribute is *undefined*, the [[Get]] operation must return *undefined*.
- [[Set]] ( _P_, _V_, _Receiver_ )
+ [[Set]] ( _propertyKey_, _value_, _receiver_ )
-
The normal return type is Boolean.
-
- If _P_ was previously observed as a non-configurable, non-writable own data property of the target, then [[Set]] must return *false* unless _V_ is the SameValue as _P_'s [[Value]] attribute.
+ If _propertyKey_ was previously observed as a non-configurable, non-writable own data property of the target, then [[Set]] must return *false* unless _value_ is the SameValue as _propertyKey_'s [[Value]] attribute.
-
- If _P_ was previously observed as a non-configurable own accessor property of the target whose [[Set]] attribute is *undefined*, the [[Set]] operation must return *false*.
+ If _propertyKey_ was previously observed as a non-configurable own accessor property of the target whose [[Setter]] attribute is *undefined*, the [[Set]] operation must return *false*.
- [[Delete]] ( _P_ )
+ [[Delete]] ( _propertyKey_ )
-
The normal return type is Boolean.
-
- If _P_ was previously observed as a non-configurable own data or accessor property of the target, [[Delete]] must return *false*.
+ If _propertyKey_ was previously observed as a non-configurable own data or accessor property of the target, [[Delete]] must return *false*.
[[OwnPropertyKeys]] ( )
@@ -3202,7 +3353,7 @@ [[OwnPropertyKeys]] ( )
The returned List must not contain any duplicate entries.
- The Type of each element of the returned List is either String or Symbol.
+ Each element of the returned List must be a property key.
The returned List must contain at least the keys of all non-configurable own properties that have previously been observed.
@@ -3234,26 +3385,28 @@ Well-Known Intrinsic Objects
Within this specification a reference such as %name% means the intrinsic object, associated with the current realm, corresponding to the name. A reference such as %name.a.b% means, as if the *"b"* property of the value of the *"a"* property of the intrinsic object %name% was accessed prior to any ECMAScript code being evaluated. Determination of the current realm and its intrinsics is described in
-
-
- Intrinsic Name
-
-
- Global Name
-
-
- ECMAScript Language Association
-
-
+
+
+
+ Intrinsic Name
+
+
+ Global Name
+
+
+ ECMAScript Language Association
+
+
+
%AggregateError%
- `AggregateError`
+ *"AggregateError"*
- The `AggregateError` constructor (constructor (
@@ -3261,10 +3414,10 @@ Well-Known Intrinsic Objects
%Array%
- `Array`
+ *"Array"*
- The Array constructor (constructor (
@@ -3272,10 +3425,10 @@ Well-Known Intrinsic Objects
%ArrayBuffer%
- `ArrayBuffer`
+ *"ArrayBuffer"*
- The ArrayBuffer constructor (constructor (
@@ -3285,7 +3438,18 @@ Well-Known Intrinsic Objects
- The prototype of Array iterator objects (
+
+
+
+ %AsyncDisposableStack%
+
+
+ *"AsyncDisposableStack"*
+
+
+ The `AsyncDisposableStack` constructor (
@@ -3295,7 +3459,7 @@ Well-Known Intrinsic Objects
- The prototype of async-from-sync iterator objects (
@@ -3305,7 +3469,7 @@ Well-Known Intrinsic Objects
- The constructor of async function objects (constructor of async function objects (
@@ -3315,7 +3479,7 @@ Well-Known Intrinsic Objects
- The constructor of async generator function objects (constructor of async generator function objects (
@@ -3343,7 +3507,7 @@ Well-Known Intrinsic Objects
%Atomics%
- `Atomics`
+ *"Atomics"*
The `Atomics` object (Well-Known Intrinsic Objects
%BigInt%
- `BigInt`
+ *"BigInt"*
- The BigInt constructor (constructor (
@@ -3365,10 +3529,10 @@ Well-Known Intrinsic Objects
%BigInt64Array%
- `BigInt64Array`
+ *"BigInt64Array"*
- The BigInt64Array constructor (constructor (
@@ -3376,10 +3540,10 @@ Well-Known Intrinsic Objects
%BigUint64Array%
- `BigUint64Array`
+ *"BigUint64Array"*
- The BigUint64Array constructor (constructor (
@@ -3387,10 +3551,10 @@ Well-Known Intrinsic Objects
%Boolean%
- `Boolean`
+ *"Boolean"*
- The Boolean constructor (constructor (
@@ -3398,10 +3562,10 @@ Well-Known Intrinsic Objects
%DataView%
- `DataView`
+ *"DataView"*
- The DataView constructor (constructor (
@@ -3409,10 +3573,10 @@ Well-Known Intrinsic Objects
%Date%
- `Date`
+ *"Date"*
- The Date constructor (constructor (
@@ -3420,7 +3584,7 @@ Well-Known Intrinsic Objects
%decodeURI%
- `decodeURI`
+ *"decodeURI"*
The `decodeURI` function (Well-Known Intrinsic Objects
%decodeURIComponent%
- `decodeURIComponent`
+ *"decodeURIComponent"*
The `decodeURIComponent` function (
+
+
+ %DisposableStack%
+
+
+ *"DisposableStack"*
+
+
+ The `DisposableStack` constructor (
+
%encodeURI%
- `encodeURI`
+ *"encodeURI"*
The `encodeURI` function (Well-Known Intrinsic Objects
%encodeURIComponent%
- `encodeURIComponent`
+ *"encodeURIComponent"*
The `encodeURIComponent` function (Well-Known Intrinsic Objects
%Error%
- `Error`
+ *"Error"*
- The Error constructor (constructor (
@@ -3475,7 +3650,7 @@ Well-Known Intrinsic Objects
%eval%
- `eval`
+ *"eval"*
The `eval` function (Well-Known Intrinsic Objects
%EvalError%
- `EvalError`
+ *"EvalError"*
- The EvalError constructor (constructor (
@@ -3497,10 +3672,21 @@ Well-Known Intrinsic Objects
%FinalizationRegistry%
- `FinalizationRegistry`
+ *"FinalizationRegistry"*
- The FinalizationRegistry constructor (constructor (
+
+
+
+ %Float16Array%
+
+
+ *"Float16Array"*
+
+
+ The `Float16Array` constructor (
@@ -3508,10 +3694,10 @@ Well-Known Intrinsic Objects
%Float32Array%
- `Float32Array`
+ *"Float32Array"*
- The Float32Array constructor (constructor (
@@ -3519,10 +3705,10 @@ Well-Known Intrinsic Objects
%Float64Array%
- `Float64Array`
+ *"Float64Array"*
- The Float64Array constructor (constructor (
@@ -3532,7 +3718,7 @@ Well-Known Intrinsic Objects
- The prototype of For-In iterator objects (
@@ -3540,10 +3726,10 @@ Well-Known Intrinsic Objects
%Function%
- `Function`
+ *"Function"*
- The Function constructor (constructor (
@@ -3553,7 +3739,7 @@ Well-Known Intrinsic Objects
- The constructor of generator function objects (constructor of generator function objects (
@@ -3571,10 +3757,10 @@ Well-Known Intrinsic Objects
%Int8Array%
- `Int8Array`
+ *"Int8Array"*
- The Int8Array constructor (constructor (
@@ -3582,10 +3768,10 @@ Well-Known Intrinsic Objects
%Int16Array%
- `Int16Array`
+ *"Int16Array"*
- The Int16Array constructor (constructor (
@@ -3593,10 +3779,10 @@ Well-Known Intrinsic Objects
%Int32Array%
- `Int32Array`
+ *"Int32Array"*
- The Int32Array constructor (constructor (
@@ -3604,7 +3790,7 @@ Well-Known Intrinsic Objects
%isFinite%
- `isFinite`
+ *"isFinite"*
The `isFinite` function (Well-Known Intrinsic Objects
%isNaN%
- `isNaN`
+ *"isNaN"*
The `isNaN` function (Well-Known Intrinsic Objects
- %IteratorPrototype%
+ %Iterator%
+ *"Iterator"*
- An object that all standard built-in iterator objects indirectly inherit from
+ The `Iterator` constructor (
+
+
+
+ %IteratorHelperPrototype%
+
+
+
+
+ The prototype of Iterator Helper objects (
@@ -3636,7 +3833,7 @@ Well-Known Intrinsic Objects
%JSON%
- `JSON`
+ *"JSON"*
The `JSON` object (Well-Known Intrinsic Objects
%Map%
- `Map`
+ *"Map"*
- The Map constructor (constructor (
@@ -3660,7 +3857,7 @@ Well-Known Intrinsic Objects
- The prototype of Map iterator objects (
@@ -3668,7 +3865,7 @@ Well-Known Intrinsic Objects
%Math%
- `Math`
+ *"Math"*
The `Math` object (Well-Known Intrinsic Objects
%Number%
- `Number`
+ *"Number"*
- The Number constructor (constructor (
@@ -3690,10 +3887,10 @@ Well-Known Intrinsic Objects
%Object%
- `Object`
+ *"Object"*
- The Object constructor (constructor (
@@ -3701,7 +3898,7 @@ Well-Known Intrinsic Objects
%parseFloat%
- `parseFloat`
+ *"parseFloat"*
The `parseFloat` function (Well-Known Intrinsic Objects
%parseInt%
- `parseInt`
+ *"parseInt"*
The `parseInt` function (Well-Known Intrinsic Objects
%Promise%
- `Promise`
+ *"Promise"*
- The Promise constructor (constructor (
@@ -3734,10 +3931,10 @@ Well-Known Intrinsic Objects
%Proxy%
- `Proxy`
+ *"Proxy"*
- The Proxy constructor (constructor (
@@ -3745,10 +3942,10 @@ Well-Known Intrinsic Objects
%RangeError%
- `RangeError`
+ *"RangeError"*
- The RangeError constructor (constructor (
@@ -3756,10 +3953,10 @@ Well-Known Intrinsic Objects
%ReferenceError%
- `ReferenceError`
+ *"ReferenceError"*
- The ReferenceError constructor (constructor (
@@ -3767,7 +3964,7 @@ Well-Known Intrinsic Objects
%Reflect%
- `Reflect`
+ *"Reflect"*
The `Reflect` object (Well-Known Intrinsic Objects
%RegExp%
- `RegExp`
+ *"RegExp"*
- The RegExp constructor (constructor (
@@ -3799,10 +3996,10 @@ Well-Known Intrinsic Objects
%Set%
- `Set`
+ *"Set"*
- The Set constructor (constructor (
@@ -3812,7 +4009,7 @@ Well-Known Intrinsic Objects
- The prototype of Set iterator objects (
@@ -3820,10 +4017,10 @@ Well-Known Intrinsic Objects
%SharedArrayBuffer%
- `SharedArrayBuffer`
+ *"SharedArrayBuffer"*
- The SharedArrayBuffer constructor (constructor (
@@ -3831,10 +4028,10 @@ Well-Known Intrinsic Objects
%String%
- `String`
+ *"String"*
- The String constructor (constructor (
@@ -3844,7 +4041,18 @@ Well-Known Intrinsic Objects
- The prototype of String iterator objects (
+
+
+
+ %SuppressedError%
+
+
+ *"SuppressedError"*
+
+
+ The `SuppressedError` constructor (
@@ -3852,10 +4060,10 @@ Well-Known Intrinsic Objects
%Symbol%
- `Symbol`
+ *"Symbol"*
- The Symbol constructor (constructor (
@@ -3863,10 +4071,10 @@ Well-Known Intrinsic Objects
%SyntaxError%
- `SyntaxError`
+ *"SyntaxError"*
- The SyntaxError constructor (constructor (
@@ -3886,7 +4094,7 @@ Well-Known Intrinsic Objects
- The super class of all typed Array constructors (constructors (
@@ -3894,10 +4102,10 @@ Well-Known Intrinsic Objects
%TypeError%
- `TypeError`
+ *"TypeError"*
- The TypeError constructor (constructor (
@@ -3905,10 +4113,10 @@ Well-Known Intrinsic Objects
%Uint8Array%
- `Uint8Array`
+ *"Uint8Array"*
- The Uint8Array constructor (constructor (
@@ -3916,10 +4124,10 @@ Well-Known Intrinsic Objects
%Uint8ClampedArray%
- `Uint8ClampedArray`
+ *"Uint8ClampedArray"*
- The Uint8ClampedArray constructor (constructor (
@@ -3927,10 +4135,10 @@ Well-Known Intrinsic Objects
%Uint16Array%
- `Uint16Array`
+ *"Uint16Array"*
- The Uint16Array constructor (constructor (
@@ -3938,10 +4146,10 @@ Well-Known Intrinsic Objects
%Uint32Array%
- `Uint32Array`
+ *"Uint32Array"*
- The Uint32Array constructor (constructor (
@@ -3949,10 +4157,10 @@ Well-Known Intrinsic Objects
%URIError%
- `URIError`
+ *"URIError"*
- The URIError constructor (constructor (
@@ -3960,10 +4168,10 @@ Well-Known Intrinsic Objects
%WeakMap%
- `WeakMap`
+ *"WeakMap"*
- The WeakMap constructor (constructor (
@@ -3971,10 +4179,10 @@ Well-Known Intrinsic Objects
%WeakRef%
- `WeakRef`
+ *"WeakRef"*
- The WeakRef constructor (constructor (
@@ -3982,10 +4190,20 @@ Well-Known Intrinsic Objects
%WeakSet%
- `WeakSet`
+ *"WeakSet"*
- The WeakSet constructor (constructor (
+
+
+
+ %WrapForValidIteratorPrototype%
+
+
+
+
+ The prototype of wrapped iterator objects returned by `Iterator.from` (
@@ -3999,30 +4217,30 @@ Well-Known Intrinsic Objects
ECMAScript Specification Types
- A specification type corresponds to meta-values that are used within algorithms to describe the semantics of ECMAScript language constructs and ECMAScript language types. The specification types include Reference, List, Completion Record, Property Descriptor, Environment Record, Abstract Closure, and Data Block. Specification type values are specification artefacts that do not necessarily correspond to any specific entity within an ECMAScript implementation. Specification type values may be used to describe intermediate results of ECMAScript expression evaluation but such values cannot be stored as properties of objects or values of ECMAScript language variables.
+ A specification type corresponds to meta-values that are used within algorithms to describe the semantics of ECMAScript language constructs and ECMAScript language types. The specification types include Reference Record, List, Completion Record, Property Descriptor, Environment Record, Abstract Closure, and Data Block. Specification type values are specification artefacts that do not necessarily correspond to any specific entity within an ECMAScript implementation. Specification type values may be used to describe intermediate results of ECMAScript expression evaluation but such values cannot be stored as properties of objects or values of ECMAScript language variables.
The Enum Specification Type
- Enums are values which are internal to the specification and not directly observable from ECMAScript code. Enums are denoted using a ~sans-serif~ typeface. For instance, a Completion Record's [[Type]] field takes on values like ~normal~, ~return~, or ~throw~. Enums have no characteristics other than their name. The name of an enum serves no purpose other than to distinguish it from other enums, and implies nothing about its usage or meaning in context.
+ Enums are values which are internal to the specification and not directly observable from ECMAScript code. Enums are denoted in upper kebab case using a ~sans-serif~ typeface. For instance, a Completion Record's [[Type]] field takes on values like ~normal~, ~return~, or ~throw~. Enums have no characteristics other than their name. The name of an enum serves no purpose other than to distinguish it from other enums, and implies nothing about its usage or meaning in context.
The List and Record Specification Types
- The List type is used to explain the evaluation of argument lists (see
+ The List type is used to explain the evaluation of argument lists (see
When an algorithm iterates over the elements of a List without specifying an order, the order used is the order of the elements in the List.
For notational convenience within this specification, a literal syntax can be used to express a new List value. For example, « 1, 2 » defines a List value that has two elements each of which is initialized to a specific value. A new empty List can be expressed as « ».
- In this specification, the phrase "the list-concatenation of _A_, _B_, ..." (where each argument is a possibly empty List) denotes a new List value whose elements are the concatenation of the elements (in order) of each of the arguments (in order).
- As applied to a List of Strings, the phrase "sorted according to lexicographic code unit order" means sorting by the numeric value of each code unit up to the length of the shorter string, and sorting the shorter string before the longer string if all are equal, as described in the abstract operation IsLessThan.
+ In this specification, the phrase “the list-concatenation of _A_, _B_, ...” (where each argument is a possibly empty List) denotes a new List value whose elements are the concatenation of the elements (in order) of each of the arguments (in order).
+ As applied to a List of Strings, the phrase “sorted according to lexicographic code unit order” means sorting by the numeric value of each code unit up to the length of the shorter string, and sorting the shorter string before the longer string if all are equal, as described in the abstract operation IsLessThan.
The Record type is used to describe data aggregations within the algorithms of this specification. A Record type value consists of one or more named fields. The value of each field is an ECMAScript language value or specification value. Field names are always enclosed in double brackets, for example [[Value]].
- For notational convenience within this specification, an object literal-like syntax can be used to express a Record value. For example, { [[Field1]]: 42, [[Field2]]: *false*, [[Field3]]: ~empty~ } defines a Record value that has three fields, each of which is initialized to a specific value. Field name order is not significant. Any fields that are not explicitly listed are considered to be absent.
- In specification text and algorithms, dot notation may be used to refer to a specific field of a Record value. For example, if R is the record shown in the previous paragraph then R.[[Field2]] is shorthand for “the field of R named [[Field2]]”.
- Schema for commonly used Record field combinations may be named, and that name may be used as a prefix to a literal Record value to identify the specific kind of aggregations that is being described. For example: PropertyDescriptor { [[Value]]: 42, [[Writable]]: *false*, [[Configurable]]: *true* }.
+ For notational convenience within this specification, an object literal-like syntax can be used to express a Record. For example, { [[Field1]]: 42, [[Field2]]: *false*, [[Field3]]: ~empty~ } defines a Record that has three fields, each of which is initialized to a specific value. Field name order is not significant. Any fields that are not explicitly listed are considered to be absent.
+ In specification text and algorithms, dot notation may be used to refer to a specific field of a Record. For example, if R is the record shown in the previous paragraph then R.[[Field2]] is shorthand for “the field of R named [[Field2]]”.
+ Schema for commonly used Record field combinations may be named, and that name may be used as a prefix to a literal Record to identify the specific kind of aggregations that is being described. For example: PropertyDescriptor { [[Value]]: 42, [[Writable]]: *false*, [[Configurable]]: *true* }.
The Set and Relation Specification Types
- The Set type is used to explain a collection of unordered elements for use in the memory model. It is distinct from the ECMAScript collection type of the same name. To disambiguate, instances of the ECMAScript collection are consistently referred to as "Set objects" within this specification. Values of the Set type are simple collections of elements, where no element appears more than once. Elements may be added to and removed from Sets. Sets may be unioned, intersected, or subtracted from each other.
- The Relation type is used to explain constraints on Sets. Values of the Relation type are Sets of ordered pairs of values from its value domain. For example, a Relation on events is a set of ordered pairs of events. For a Relation _R_ and two values _a_ and _b_ in the value domain of _R_, _a_ _R_ _b_ is shorthand for saying the ordered pair (_a_, _b_) is a member of _R_. A Relation is the least Relation with respect to some conditions when it is the smallest Relation that satisfies those conditions.
+ The Set type is used to explain a collection of unordered elements for use in the memory model. It is distinct from the ECMAScript collection type of the same name. To disambiguate, instances of the ECMAScript collection are consistently referred to as “Set objects” within this specification. Values of the Set type are simple collections of elements, where no element appears more than once. Elements may be added to and removed from Sets. Sets may be unioned, intersected, or subtracted from each other.
+ The Relation type is used to explain constraints on Sets. Values of the Relation type are Sets of ordered pairs of values from its value domain. For example, a Relation on Memory events is a set of ordered pairs of Memory events. For a Relation _R_ and two values _a_ and _b_ in the value domain of _R_, _a_ _R_ _b_ is shorthand for saying the ordered pair (_a_, _b_) is a member of _R_. A Relation is the least Relation with respect to some conditions when it is the smallest Relation that satisfies those conditions.
A strict partial order is a Relation value _R_ that satisfies the following.
-
@@ -4058,17 +4276,19 @@
The Completion Record Specification Type
Completion Records have the fields defined in
-
-
- Field Name
-
-
- Value
-
-
- Meaning
-
-
+
+
+
+ Field Name
+
+
+ Value
+
+
+ Meaning
+
+
+
[[Type]]
@@ -4124,6 +4344,8 @@
): a normal completion
+ - skip return checks
+ - true
1. Return Completion Record { [[Type]]: ~normal~, [[Value]]: _value_, [[Target]]: ~empty~ }.
@@ -4143,6 +4365,19 @@
+
+
+ ReturnCompletion (
+ _value_: an ECMAScript language value,
+ ): a return completion
+
+
+
+
+ 1. Return Completion Record { [[Type]]: ~return~, [[Value]]: _value_, [[Target]]: ~empty~ }.
+
+
+
UpdateEmpty (
@@ -4163,15 +4398,17 @@
The Reference Record Specification Type
The Reference Record type is used to explain the behaviour of such operators as `delete`, `typeof`, the assignment operators, the `super` keyword and other language features. For example, the left-hand operand of an assignment is expected to produce a Reference Record.
- A Reference Record is a resolved name or property binding; its fields are defined by
+ A Reference Record is a resolved name or (possibly not-yet-resolved) property binding; its fields are defined by
-
- Field Name
- Value
- Meaning
-
+
+
+ Field Name
+ Value
+ Meaning
+
+
[[Base]]
an ECMAScript language value, an Environment Record, or ~unresolvable~
@@ -4179,8 +4416,8 @@ The Reference Record Specification Type
[[ReferencedName]]
- a String, a Symbol, or a Private Name
- The name of the binding. Always a String if [[Base]] value is an Environment Record.
+ an ECMAScript language value or a Private Name
+ The name of the binding. Always a String if [[Base]] value is an Environment Record. Otherwise, may be an ECMAScript language value other than a String or a Symbol until ToPropertyKey is performed.
[[Strict]]
@@ -4200,76 +4437,81 @@ The Reference Record Specification Type
IsPropertyReference (
- _V_: a Reference Record,
+ _refRecord_: a Reference Record,
): a Boolean
- 1. If _V_.[[Base]] is ~unresolvable~, return *false*.
- 1. If _V_.[[Base]] is an Environment Record, return *false*; otherwise return *true*.
+ 1. If _refRecord_.[[Base]] is ~unresolvable~, return *false*.
+ 1. If _refRecord_.[[Base]] is an Environment Record, return *false*.
+ 1. Return *true*.
IsUnresolvableReference (
- _V_: a Reference Record,
+ _refRecord_: a Reference Record,
): a Boolean
- 1. If _V_.[[Base]] is ~unresolvable~, return *true*; otherwise return *false*.
+ 1. If _refRecord_.[[Base]] is ~unresolvable~, return *true*.
+ 1. Return *false*.
IsSuperReference (
- _V_: a Reference Record,
+ _refRecord_: a Reference Record,
): a Boolean
- 1. If _V_.[[ThisValue]] is not ~empty~, return *true*; otherwise return *false*.
+ 1. If _refRecord_.[[ThisValue]] is ~empty~, return *false*.
+ 1. Return *true*.
IsPrivateReference (
- _V_: a Reference Record,
+ _refRecord_: a Reference Record,
): a Boolean
- 1. If _V_.[[ReferencedName]] is a Private Name, return *true*; otherwise return *false*.
+ 1. If _refRecord_.[[ReferencedName]] is a Private Name, return *true*.
+ 1. Return *false*.
GetValue (
- _V_: a Reference Record or an ECMAScript language value,
+ _refRecord_: a Reference Record or an ECMAScript language value,
): either a normal completion containing an ECMAScript language value or an abrupt completion
- 1. If _V_ is not a Reference Record, return _V_.
- 1. If IsUnresolvableReference(_V_) is *true*, throw a *ReferenceError* exception.
- 1. If IsPropertyReference(_V_) is *true*, then
- 1. [id="step-getvalue-toobject"] Let _baseObj_ be ? ToObject(_V_.[[Base]]).
- 1. If IsPrivateReference(_V_) is *true*, then
- 1. Return ? PrivateGet(_baseObj_, _V_.[[ReferencedName]]).
- 1. Return ? _baseObj_.[[Get]] (_V_.[[ReferencedName]], GetThisValue(_V_)).
- 1. Else,
- 1. Let _base_ be _V_.[[Base]].
- 1. Assert: _base_ is an Environment Record.
- 1. Return ? _base_.GetBindingValue (_V_.[[ReferencedName]], _V_.[[Strict]]) (see _baseObj_.[[Get]](_refRecord_.[[ReferencedName]], GetThisValue(_refRecord_)) .
+ 1. Let _base_ be _refRecord_.[[Base]].
+ 1. Assert: _base_ is an Environment Record.
+ 1. Return ? _base_.GetBindingValue(_refRecord_.[[ReferencedName]], _refRecord_.[[Strict]]) (see
The object that may be created in step
@@ -4279,30 +4521,31 @@
PutValue (
- _V_: a Reference Record or an ECMAScript language value,
- _W_: an ECMAScript language value,
+ _refRecord_: a Reference Record or an ECMAScript language value,
+ _value_: an ECMAScript language value,
): either a normal completion containing ~unused~ or an abrupt completion
- 1. If _V_ is not a Reference Record, throw a *ReferenceError* exception.
- 1. If IsUnresolvableReference(_V_) is *true*, then
- 1. If _V_.[[Strict]] is *true*, throw a *ReferenceError* exception.
+ 1. If _refRecord_ is not a Reference Record, throw a *ReferenceError* exception.
+ 1. If IsUnresolvableReference(_refRecord_) is *true*, then
+ 1. If _refRecord_.[[Strict]] is *true*, throw a *ReferenceError* exception.
1. Let _globalObj_ be GetGlobalObject().
- 1. Perform ? Set(_globalObj_, _V_.[[ReferencedName]], _W_, *false*).
+ 1. Perform ? Set(_globalObj_, _refRecord_.[[ReferencedName]], _value_, *false*).
1. Return ~unused~.
- 1. If IsPropertyReference(_V_) is *true*, then
- 1. [id="step-putvalue-toobject"] Let _baseObj_ be ? ToObject(_V_.[[Base]]).
- 1. If IsPrivateReference(_V_) is *true*, then
- 1. Return ? PrivateSet(_baseObj_, _V_.[[ReferencedName]], _W_).
- 1. Let _succeeded_ be ? _baseObj_.[[Set]] (_V_.[[ReferencedName]], _W_, GetThisValue(_V_)).
- 1. If _succeeded_ is *false* and _V_.[[Strict]] is *true*, throw a *TypeError* exception.
+ 1. If IsPropertyReference(_refRecord_) is *true*, then
+ 1. [id="step-putvalue-toobject"] Let _baseObj_ be ? ToObject(_refRecord_.[[Base]]).
+ 1. If IsPrivateReference(_refRecord_) is *true*, then
+ 1. Return ? PrivateSet(_baseObj_, _refRecord_.[[ReferencedName]], _value_).
+ 1. If _refRecord_.[[ReferencedName]] is not a property key, then
+ 1. Set _refRecord_.[[ReferencedName]] to ? ToPropertyKey(_refRecord_.[[ReferencedName]]).
+ 1. Let _succeeded_ be ? _baseObj_.[[Set]](_refRecord_.[[ReferencedName]], _value_, GetThisValue(_refRecord_)) .
+ 1. If _succeeded_ is *false* and _refRecord_.[[Strict]] is *true*, throw a *TypeError* exception.
1. Return ~unused~.
- 1. Else,
- 1. Let _base_ be _V_.[[Base]].
- 1. Assert: _base_ is an Environment Record.
- 1. Return ? _base_.SetMutableBinding (_V_.[[ReferencedName]], _W_, _V_.[[Strict]]) (see _base_.SetMutableBinding(_refRecord_.[[ReferencedName]], _value_, _refRecord_.[[Strict]]) (see
The object that may be created in step
@@ -4312,31 +4555,32 @@
GetThisValue (
- _V_: a Reference Record,
+ _refRecord_: a Reference Record,
): an ECMAScript language value
- 1. Assert: IsPropertyReference(_V_) is *true*.
- 1. If IsSuperReference(_V_) is *true*, return _V_.[[ThisValue]]; otherwise return _V_.[[Base]].
+ 1. Assert: IsPropertyReference(_refRecord_) is *true*.
+ 1. If IsSuperReference(_refRecord_) is *true*, return _refRecord_.[[ThisValue]].
+ 1. Return _refRecord_.[[Base]].
InitializeReferencedBinding (
- _V_: a Reference Record,
- _W_: an ECMAScript language value,
+ _refRecord_: a Reference Record,
+ _value_: an ECMAScript language value,
): either a normal completion containing ~unused~ or an abrupt completion
- 1. Assert: IsUnresolvableReference(_V_) is *false*.
- 1. Let _base_ be _V_.[[Base]].
+ 1. Assert: IsUnresolvableReference(_refRecord_) is *false*.
+ 1. Let _base_ be _refRecord_.[[Base]].
1. Assert: _base_ is an Environment Record.
- 1. Return ? _base_.InitializeBinding(_V_.[[ReferencedName]], _W_).
+ 1. Return ? _base_.InitializeBinding(_refRecord_.[[ReferencedName]], _value_).
@@ -4350,9 +4594,9 @@
- 1. Let _privEnv_ be the running execution context's PrivateEnvironment.
- 1. Assert: _privEnv_ is not *null*.
- 1. Let _privateName_ be ResolvePrivateIdentifier(_privEnv_, _privateIdentifier_).
+ 1. Let _privateEnv_ be the running execution context's PrivateEnvironment.
+ 1. Assert: _privateEnv_ is not *null*.
+ 1. Let _privateName_ be ResolvePrivateIdentifier(_privateEnv_, _privateIdentifier_).
1. Return the Reference Record { [[Base]]: _baseValue_, [[ReferencedName]]: _privateName_, [[Strict]]: *true*, [[ThisValue]]: ~empty~ }.
@@ -4361,21 +4605,20 @@
The Property Descriptor Specification Type
The Property Descriptor type is used to explain the manipulation and reification of Object property attributes. A Property Descriptor is a Record with zero or more fields, where each field's name is an attribute name and its value is a corresponding attribute value as specified in
- Property Descriptor values may be further classified as data Property Descriptors and accessor Property Descriptors based upon the existence or use of certain fields. A data Property Descriptor is one that includes any fields named either [[Value]] or [[Writable]]. An accessor Property Descriptor is one that includes any fields named either [[Get]] or [[Set]]. Any Property Descriptor may have fields named [[Enumerable]] and [[Configurable]]. A Property Descriptor value may not be both a data Property Descriptor and an accessor Property Descriptor; however, it may be neither (in which case it is a generic Property Descriptor). A fully populated Property Descriptor is one that is either an accessor Property Descriptor or a data Property Descriptor and that has all of the corresponding fields defined in
+ Property Descriptor values may be further classified as data Property Descriptors and accessor Property Descriptors based upon the existence or use of certain fields. A data Property Descriptor is one that includes any fields named either [[Value]] or [[Writable]]. An accessor Property Descriptor is one that includes any fields named either [[Getter]] or [[Setter]]. Any Property Descriptor may have fields named [[Enumerable]] and [[Configurable]]. A Property Descriptor value may not be both a data Property Descriptor and an accessor Property Descriptor; however, it may be neither (in which case it is a generic Property Descriptor). A fully populated Property Descriptor is one that is either an accessor Property Descriptor or a data Property Descriptor and that has all of the corresponding fields defined in
The following abstract operations are used in this specification to operate upon Property Descriptor values:
IsAccessorDescriptor (
- _Desc_: a Property Descriptor or *undefined*,
+ _propertyDesc_: a Property Descriptor,
): a Boolean
- 1. If _Desc_ is *undefined*, return *false*.
- 1. If _Desc_ has a [[Get]] field, return *true*.
- 1. If _Desc_ has a [[Set]] field, return *true*.
+ 1. If _propertyDesc_ has a [[Getter]] field, return *true*.
+ 1. If _propertyDesc_ has a [[Setter]] field, return *true*.
1. Return *false*.
@@ -4383,15 +4626,14 @@
IsDataDescriptor (
- _Desc_: a Property Descriptor or *undefined*,
+ _propertyDesc_: a Property Descriptor,
): a Boolean
- 1. If _Desc_ is *undefined*, return *false*.
- 1. If _Desc_ has a [[Value]] field, return *true*.
- 1. If _Desc_ has a [[Writable]] field, return *true*.
+ 1. If _propertyDesc_ has a [[Value]] field, return *true*.
+ 1. If _propertyDesc_ has a [[Writable]] field, return *true*.
1. Return *false*.
@@ -4399,15 +4641,14 @@
IsGenericDescriptor (
- _Desc_: a Property Descriptor or *undefined*,
+ _propertyDesc_: a Property Descriptor,
): a Boolean
- 1. If _Desc_ is *undefined*, return *false*.
- 1. If IsAccessorDescriptor(_Desc_) is *true*, return *false*.
- 1. If IsDataDescriptor(_Desc_) is *true*, return *false*.
+ 1. If IsAccessorDescriptor(_propertyDesc_) is *true*, return *false*.
+ 1. If IsDataDescriptor(_propertyDesc_) is *true*, return *false*.
1. Return *true*.
@@ -4415,27 +4656,27 @@
FromPropertyDescriptor (
- _Desc_: a Property Descriptor or *undefined*,
+ _propertyDesc_: a Property Descriptor or *undefined*,
): an Object or *undefined*
- 1. If _Desc_ is *undefined*, return *undefined*.
+ 1. If _propertyDesc_ is *undefined*, return *undefined*.
1. Let _obj_ be OrdinaryObjectCreate(%Object.prototype%).
1. Assert: _obj_ is an extensible ordinary object with no own properties.
- 1. If _Desc_ has a [[Value]] field, then
- 1. Perform ! CreateDataPropertyOrThrow(_obj_, *"value"*, _Desc_.[[Value]]).
- 1. If _Desc_ has a [[Writable]] field, then
- 1. Perform ! CreateDataPropertyOrThrow(_obj_, *"writable"*, _Desc_.[[Writable]]).
- 1. If _Desc_ has a [[Get]] field, then
- 1. Perform ! CreateDataPropertyOrThrow(_obj_, *"get"*, _Desc_.[[Get]]).
- 1. If _Desc_ has a [[Set]] field, then
- 1. Perform ! CreateDataPropertyOrThrow(_obj_, *"set"*, _Desc_.[[Set]]).
- 1. If _Desc_ has an [[Enumerable]] field, then
- 1. Perform ! CreateDataPropertyOrThrow(_obj_, *"enumerable"*, _Desc_.[[Enumerable]]).
- 1. If _Desc_ has a [[Configurable]] field, then
- 1. Perform ! CreateDataPropertyOrThrow(_obj_, *"configurable"*, _Desc_.[[Configurable]]).
+ 1. If _propertyDesc_ has a [[Value]] field, then
+ 1. Perform ! CreateDataPropertyOrThrow(_obj_, *"value"*, _propertyDesc_.[[Value]]).
+ 1. If _propertyDesc_ has a [[Writable]] field, then
+ 1. Perform ! CreateDataPropertyOrThrow(_obj_, *"writable"*, _propertyDesc_.[[Writable]]).
+ 1. If _propertyDesc_ has a [[Getter]] field, then
+ 1. Perform ! CreateDataPropertyOrThrow(_obj_, *"get"*, _propertyDesc_.[[Getter]]).
+ 1. If _propertyDesc_ has a [[Setter]] field, then
+ 1. Perform ! CreateDataPropertyOrThrow(_obj_, *"set"*, _propertyDesc_.[[Setter]]).
+ 1. If _propertyDesc_ has an [[Enumerable]] field, then
+ 1. Perform ! CreateDataPropertyOrThrow(_obj_, *"enumerable"*, _propertyDesc_.[[Enumerable]]).
+ 1. If _propertyDesc_ has a [[Configurable]] field, then
+ 1. Perform ! CreateDataPropertyOrThrow(_obj_, *"configurable"*, _propertyDesc_.[[Configurable]]).
1. Return _obj_.
@@ -4443,64 +4684,64 @@
ToPropertyDescriptor (
- _Obj_: an ECMAScript language value,
+ _obj_: an ECMAScript language value,
): either a normal completion containing a Property Descriptor or a throw completion
- 1. If _Obj_ is not an Object, throw a *TypeError* exception.
- 1. Let _desc_ be a new Property Descriptor that initially has no fields.
- 1. Let _hasEnumerable_ be ? HasProperty(_Obj_, *"enumerable"*).
+ 1. If _obj_ is not an Object, throw a *TypeError* exception.
+ 1. Let _propertyDesc_ be a new Property Descriptor that initially has no fields.
+ 1. Let _hasEnumerable_ be ? HasProperty(_obj_, *"enumerable"*).
1. If _hasEnumerable_ is *true*, then
- 1. Let _enumerable_ be ToBoolean(? Get(_Obj_, *"enumerable"*)).
- 1. Set _desc_.[[Enumerable]] to _enumerable_.
- 1. Let _hasConfigurable_ be ? HasProperty(_Obj_, *"configurable"*).
+ 1. Let _enumerable_ be ToBoolean(? Get(_obj_, *"enumerable"*)).
+ 1. Set _propertyDesc_.[[Enumerable]] to _enumerable_.
+ 1. Let _hasConfigurable_ be ? HasProperty(_obj_, *"configurable"*).
1. If _hasConfigurable_ is *true*, then
- 1. Let _configurable_ be ToBoolean(? Get(_Obj_, *"configurable"*)).
- 1. Set _desc_.[[Configurable]] to _configurable_.
- 1. Let _hasValue_ be ? HasProperty(_Obj_, *"value"*).
+ 1. Let _configurable_ be ToBoolean(? Get(_obj_, *"configurable"*)).
+ 1. Set _propertyDesc_.[[Configurable]] to _configurable_.
+ 1. Let _hasValue_ be ? HasProperty(_obj_, *"value"*).
1. If _hasValue_ is *true*, then
- 1. Let _value_ be ? Get(_Obj_, *"value"*).
- 1. Set _desc_.[[Value]] to _value_.
- 1. Let _hasWritable_ be ? HasProperty(_Obj_, *"writable"*).
+ 1. Let _value_ be ? Get(_obj_, *"value"*).
+ 1. Set _propertyDesc_.[[Value]] to _value_.
+ 1. Let _hasWritable_ be ? HasProperty(_obj_, *"writable"*).
1. If _hasWritable_ is *true*, then
- 1. Let _writable_ be ToBoolean(? Get(_Obj_, *"writable"*)).
- 1. Set _desc_.[[Writable]] to _writable_.
- 1. Let _hasGet_ be ? HasProperty(_Obj_, *"get"*).
+ 1. Let _writable_ be ToBoolean(? Get(_obj_, *"writable"*)).
+ 1. Set _propertyDesc_.[[Writable]] to _writable_.
+ 1. Let _hasGet_ be ? HasProperty(_obj_, *"get"*).
1. If _hasGet_ is *true*, then
- 1. Let _getter_ be ? Get(_Obj_, *"get"*).
+ 1. Let _getter_ be ? Get(_obj_, *"get"*).
1. If IsCallable(_getter_) is *false* and _getter_ is not *undefined*, throw a *TypeError* exception.
- 1. Set _desc_.[[Get]] to _getter_.
- 1. Let _hasSet_ be ? HasProperty(_Obj_, *"set"*).
+ 1. Set _propertyDesc_.[[Getter]] to _getter_.
+ 1. Let _hasSet_ be ? HasProperty(_obj_, *"set"*).
1. If _hasSet_ is *true*, then
- 1. Let _setter_ be ? Get(_Obj_, *"set"*).
+ 1. Let _setter_ be ? Get(_obj_, *"set"*).
1. If IsCallable(_setter_) is *false* and _setter_ is not *undefined*, throw a *TypeError* exception.
- 1. Set _desc_.[[Set]] to _setter_.
- 1. If _desc_ has a [[Get]] field or _desc_ has a [[Set]] field, then
- 1. If _desc_ has a [[Value]] field or _desc_ has a [[Writable]] field, throw a *TypeError* exception.
- 1. Return _desc_.
+ 1. Set _propertyDesc_.[[Setter]] to _setter_.
+ 1. If _propertyDesc_ has a [[Getter]] field or _propertyDesc_ has a [[Setter]] field, then
+ 1. If _propertyDesc_ has a [[Value]] field or _propertyDesc_ has a [[Writable]] field, throw a *TypeError* exception.
+ 1. Return _propertyDesc_.
CompletePropertyDescriptor (
- _Desc_: a Property Descriptor,
+ _propertyDesc_: a Property Descriptor,
): ~unused~
- 1. Let _like_ be the Record { [[Value]]: *undefined*, [[Writable]]: *false*, [[Get]]: *undefined*, [[Set]]: *undefined*, [[Enumerable]]: *false*, [[Configurable]]: *false* }.
- 1. If IsGenericDescriptor(_Desc_) is *true* or IsDataDescriptor(_Desc_) is *true*, then
- 1. If _Desc_ does not have a [[Value]] field, set _Desc_.[[Value]] to _like_.[[Value]].
- 1. If _Desc_ does not have a [[Writable]] field, set _Desc_.[[Writable]] to _like_.[[Writable]].
+ 1. Let _like_ be the Record { [[Value]]: *undefined*, [[Writable]]: *false*, [[Getter]]: *undefined*, [[Setter]]: *undefined*, [[Enumerable]]: *false*, [[Configurable]]: *false* }.
+ 1. If IsGenericDescriptor(_propertyDesc_) is *true* or IsDataDescriptor(_propertyDesc_) is *true*, then
+ 1. If _propertyDesc_ does not have a [[Value]] field, set _propertyDesc_.[[Value]] to _like_.[[Value]].
+ 1. If _propertyDesc_ does not have a [[Writable]] field, set _propertyDesc_.[[Writable]] to _like_.[[Writable]].
1. Else,
- 1. If _Desc_ does not have a [[Get]] field, set _Desc_.[[Get]] to _like_.[[Get]].
- 1. If _Desc_ does not have a [[Set]] field, set _Desc_.[[Set]] to _like_.[[Set]].
- 1. If _Desc_ does not have an [[Enumerable]] field, set _Desc_.[[Enumerable]] to _like_.[[Enumerable]].
- 1. If _Desc_ does not have a [[Configurable]] field, set _Desc_.[[Configurable]] to _like_.[[Configurable]].
+ 1. If _propertyDesc_ does not have a [[Getter]] field, set _propertyDesc_.[[Getter]] to _like_.[[Getter]].
+ 1. If _propertyDesc_ does not have a [[Setter]] field, set _propertyDesc_.[[Setter]] to _like_.[[Setter]].
+ 1. If _propertyDesc_ does not have an [[Enumerable]] field, set _propertyDesc_.[[Enumerable]] to _like_.[[Enumerable]].
+ 1. If _propertyDesc_ does not have a [[Configurable]] field, set _propertyDesc_.[[Configurable]] to _like_.[[Configurable]].
1. Return ~unused~.
@@ -4514,25 +4755,25 @@ The Environment Record Specification Type
The Abstract Closure Specification Type
The Abstract Closure specification type is used to refer to algorithm steps together with a collection of values. Abstract Closures are meta-values and are invoked using function application style such as _closure_(_arg1_, _arg2_). Like abstract operations, invocations perform the algorithm steps described by the Abstract Closure.
- In algorithm steps that create an Abstract Closure, values are captured with the verb "capture" followed by a list of aliases. When an Abstract Closure is created, it captures the value that is associated with each alias at that time. In steps that specify the algorithm to be performed when an Abstract Closure is called, each captured value is referred to by the alias that was used to capture the value.
+ In algorithm steps that create an Abstract Closure, values are captured with the verb “capture” followed by a list of aliases. When an Abstract Closure is created, it captures the value that is associated with each alias at that time. In steps that specify the algorithm to be performed when an Abstract Closure is called, each captured value is referred to by the alias that was used to capture the value.
If an Abstract Closure returns a Completion Record, that Completion Record must be either a normal completion or a throw completion.
Abstract Closures are created inline as part of other algorithms, shown in the following example.
1. Let _addend_ be 41.
1. Let _closure_ be a new Abstract Closure with parameters (_x_) that captures _addend_ and performs the following steps when called:
1. Return _x_ + _addend_.
- 1. Let _val_ be _closure_(1).
- 1. Assert: _val_ is 42.
+ 1. Let _value_ be _closure_(1).
+ 1. Assert: _value_ is 42.
Data Blocks
The Data Block specification type is used to describe a distinct and mutable sequence of byte-sized (8 bit) numeric values. A byte value is an integer in the inclusive interval from 0 to 255. A Data Block value is created with a fixed number of bytes that each have the initial value 0.
- For notational convenience within this specification, an array-like syntax can be used to access the individual bytes of a Data Block value. This notation presents a Data Block value as a 0-origined integer-indexed sequence of bytes. For example, if _db_ is a 5 byte Data Block value then _db_[2] can be used to access its 3rd byte.
+ For notational convenience within this specification, an array-like syntax can be used to access the individual bytes of a Data Block value. This notation presents a Data Block value as a 0-based integer-indexed sequence of bytes. For example, if _dataBlock_ is a 5 byte Data Block value then _dataBlock_[2] can be used to access its 3rd byte.
A data block that resides in memory that can be referenced from multiple agents concurrently is designated a Shared Data Block. A Shared Data Block has an identity (for the purposes of equality testing Shared Data Block values) that is address-free: it is tied not to the virtual addresses the block is mapped to in any process, but to the set of locations in memory that the block represents. Two data blocks are equal only if the sets of the locations they contain are equal; otherwise, they are not equal and the intersection of the sets of locations they contain is empty. Finally, Shared Data Blocks can be distinguished from Data Blocks.
The semantics of Shared Data Blocks is defined using Shared Data Block events by the memory model. Abstract operations below introduce Shared Data Block events and act as the interface between evaluation semantics and the event semantics of the memory model. The events form a candidate execution, on which the memory model acts as a filter. Please consult the memory model for full semantics.
- Shared Data Block events are modeled by Records, defined in the memory model.
+ Shared Data Block events are modelled by Records, defined in the memory model.
The following abstract operations are used in this specification to operate upon Data Block values:
@@ -4545,9 +4786,9 @@
1. If _size_ > 253 - 1, throw a *RangeError* exception.
- 1. Let _db_ be a new Data Block value consisting of _size_ bytes. If it is impossible to create such a Data Block, throw a *RangeError* exception.
- 1. Set all of the bytes of _db_ to 0.
- 1. Return _db_.
+ 1. Let _dataBlock_ be a new Data Block value consisting of _size_ bytes. If it is impossible to create such a Data Block, throw a *RangeError* exception.
+ 1. Set all of the bytes of _dataBlock_ to 0.
+ 1. Return _dataBlock_.
@@ -4560,13 +4801,14 @@
- 1. Let _db_ be a new Shared Data Block value consisting of _size_ bytes. If it is impossible to create such a Shared Data Block, throw a *RangeError* exception.
- 1. Let _execution_ be the [[CandidateExecution]] field of the surrounding agent's Agent Record.
+ 1. Let _dataBlock_ be a new Shared Data Block value consisting of _size_ bytes. If it is impossible to create such a Shared Data Block, throw a *RangeError* exception.
+ 1. Let _agentRecord_ be the Agent Record of the surrounding agent.
+ 1. Let _execution_ be _agentRecord_.[[CandidateExecution]].
1. Let _eventsRecord_ be the Agent Events Record of _execution_.[[EventsRecords]] whose [[AgentSignifier]] is AgentSignifier().
1. Let _zero_ be « 0 ».
- 1. For each index _i_ of _db_, do
- 1. Append WriteSharedMemory { [[Order]]: ~init~, [[NoTear]]: *true*, [[Block]]: _db_, [[ByteIndex]]: _i_, [[ElementSize]]: 1, [[Payload]]: _zero_ } to _eventsRecord_.[[EventList]].
- 1. Return _db_.
+ 1. For each index _index_ of _dataBlock_, do
+ 1. Append WriteSharedMemory { [[Order]]: ~init~, [[NoTear]]: *true*, [[Block]]: _dataBlock_, [[ByteIndex]]: _index_, [[ElementSize]]: 1, [[Payload]]: _zero_ } to _eventsRecord_.[[EventList]].
+ 1. Return _dataBlock_.
@@ -4590,7 +4832,8 @@
1. Assert: _toIndex_ + _count_ ≤ _toSize_.
1. Repeat, while _count_ > 0,
1. If _fromBlock_ is a Shared Data Block, then
- 1. Let _execution_ be the [[CandidateExecution]] field of the surrounding agent's Agent Record.
+ 1. Let _agentRecord_ be the Agent Record of the surrounding agent.
+ 1. Let _execution_ be _agentRecord_.[[CandidateExecution]].
1. Let _eventsRecord_ be the Agent Events Record of _execution_.[[EventsRecords]] whose [[AgentSignifier]] is AgentSignifier().
1. Let _bytes_ be a List whose sole element is a nondeterministically chosen byte value.
1. NOTE: In implementations, _bytes_ is the result of a non-atomic read instruction on the underlying hardware. The nondeterminism is a semantic prescription of the memory model to describe observable behaviour of hardware with weak consistency.
@@ -4615,23 +4858,25 @@
The PrivateElement Specification Type
The PrivateElement type is a Record used in the specification of private class fields, methods, and accessors. Although Property Descriptors are not used for private elements, private fields behave similarly to non-configurable, non-enumerable, writable data properties, private methods behave similarly to non-configurable, non-enumerable, non-writable data properties, and private accessors behave similarly to non-configurable, non-enumerable accessor properties.
- Values of the PrivateElement type are Record values whose fields are defined by
+ Values of the PrivateElement type are Records whose fields are defined by
-
-
- Field Name
-
-
- Values of the [[Kind]] field for which it is present
-
-
- Value
-
-
- Meaning
-
-
+
+
+
+ Field Name
+
+
+ Values of the [[Kind]] field for which it is present
+
+
+ Value
+
+
+ Meaning
+
+
+
[[Key]]
@@ -4676,7 +4921,7 @@ The PrivateElement Specification Type
- [[Get]]
+ [[Getter]]
~accessor~
@@ -4690,7 +4935,7 @@ The PrivateElement Specification Type
- [[Set]]
+ [[Setter]]
~accessor~
@@ -4709,20 +4954,22 @@ The PrivateElement Specification Type
The ClassFieldDefinition Record Specification Type
The ClassFieldDefinition type is a Record used in the specification of class fields.
- Values of the ClassFieldDefinition type are Record values whose fields are defined by
+ Values of the ClassFieldDefinition type are Records whose fields are defined by
-
-
- Field Name
-
-
- Value
-
-
- Meaning
-
-
+
+
+
+ Field Name
+
+
+ Value
+
+
+ Meaning
+
+
+
[[Name]]
@@ -4751,26 +4998,28 @@ The ClassFieldDefinition Record Specification Type
Private Names
- The Private Name specification type is used to describe a globally unique value (one which differs from any other Private Name, even if they are otherwise indistinguishable) which represents the key of a private class element (field, method, or accessor). Each Private Name has an associated immutable [[Description]] which is a String value. A Private Name may be installed on any ECMAScript object with PrivateFieldAdd or PrivateMethodOrAccessorAdd, and then read or written using PrivateGet and PrivateSet.
+ The Private Name specification type is used to describe a globally unique value (one which differs from any other Private Name, even if they are otherwise indistinguishable) which represents the key of a private class element (field, method, or accessor). Each Private Name has an immutable [[Description]] internal slot which is a String. A Private Name may be installed on any ECMAScript object with PrivateFieldAdd or PrivateMethodOrAccessorAdd, and then read or written using PrivateGet and PrivateSet.
The ClassStaticBlockDefinition Record Specification Type
- A ClassStaticBlockDefinition Record is a Record value used to encapsulate the executable code for a class static initialization block.
+ A ClassStaticBlockDefinition Record is a Record used to encapsulate the executable code for a class static initialization block.
ClassStaticBlockDefinition Records have the fields listed in
-
-
- Field Name
-
-
- Value
-
-
- Meaning
-
-
+
+
+
+ Field Name
+
+
+ Value
+
+
+ Meaning
+
+
+
[[BodyFunction]]
@@ -4810,8 +5059,8 @@
1. If _input_ is an Object, then
- 1. Let _exoticToPrim_ be ? GetMethod(_input_, @@toPrimitive).
- 1. If _exoticToPrim_ is not *undefined*, then
+ 1. Let _exoticToPrimitive_ be ? GetMethod(_input_, %Symbol.toPrimitive%).
+ 1. If _exoticToPrimitive_ is not *undefined*, then
1. If _preferredType_ is not present, then
1. Let _hint_ be *"default"*.
1. Else if _preferredType_ is ~string~, then
@@ -4819,21 +5068,21 @@
1. Else,
1. Assert: _preferredType_ is ~number~.
1. Let _hint_ be *"number"*.
- 1. Let _result_ be ? Call(_exoticToPrim_, _input_, « _hint_ »).
+ 1. Let _result_ be ? Call(_exoticToPrimitive_, _input_, « _hint_ »).
1. If _result_ is not an Object, return _result_.
1. Throw a *TypeError* exception.
- 1. If _preferredType_ is not present, let _preferredType_ be ~number~.
+ 1. If _preferredType_ is not present, set _preferredType_ to ~number~.
1. Return ? OrdinaryToPrimitive(_input_, _preferredType_).
1. Return _input_.
- When ToPrimitive is called without a hint, then it generally behaves as if the hint were ~number~. However, objects may over-ride this behaviour by defining a @@toPrimitive method. Of the objects defined in this specification only Dates (see
+ When ToPrimitive is called without a hint, then it generally behaves as if the hint were ~number~. However, objects may over-ride this behaviour by defining a %Symbol.toPrimitive% method. Of the objects defined in this specification only Dates (see
OrdinaryToPrimitive (
- _O_: an Object,
+ _obj_: an Object,
_hint_: ~string~ or ~number~,
): either a normal completion containing an ECMAScript language value or a throw completion
@@ -4845,29 +5094,30 @@
1. Else,
1. Let _methodNames_ be « *"valueOf"*, *"toString"* ».
1. For each element _name_ of _methodNames_, do
- 1. Let _method_ be ? Get(_O_, _name_).
+ 1. Let _method_ be ? Get(_obj_, _name_).
1. If IsCallable(_method_) is *true*, then
- 1. Let _result_ be ? Call(_method_, _O_).
+ 1. Let _result_ be ? Call(_method_, _obj_).
1. If _result_ is not an Object, return _result_.
1. Throw a *TypeError* exception.
-
+
ToBoolean (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): a Boolean
- description
- - It converts _argument_ to a value of type Boolean.
+ - It converts _arg_ to a value of type Boolean.
- 1. If _argument_ is a Boolean, return _argument_.
- 1. If _argument_ is one of *undefined*, *null*, *+0*𝔽, *-0*𝔽, *NaN*, *0*ℤ, or the empty String, return *false*.
- 1. [id="step-to-boolean-web-compat-insertion-point"] NOTE: This step is replaced in section
@@ -4875,41 +5125,41 @@
ToNumeric (
- _value_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing either a Number or a BigInt, or a throw completion
- description
- - It returns _value_ converted to a Number or a BigInt.
+ - It returns _arg_ converted to a Number or a BigInt.
- 1. Let _primValue_ be ? ToPrimitive(_value_, ~number~).
- 1. If _primValue_ is a BigInt, return _primValue_.
- 1. Return ? ToNumber(_primValue_) .
+ 1. Let _primitiveValue_ be ? ToPrimitive(_arg_, ~number~).
+ 1. If _primitiveValue_ is a BigInt, return _primitiveValue_.
+ 1. Return ? ToNumber(_primitiveValue_) .
ToNumber (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing a Number or a throw completion
- description
- - It converts _argument_ to a value of type Number.
+ - It converts _arg_ to a value of type Number.
- 1. If _argument_ is a Number, return _argument_.
- 1. If _argument_ is either a Symbol or a BigInt, throw a *TypeError* exception.
- 1. If _argument_ is *undefined*, return *NaN*.
- 1. If _argument_ is either *null* or *false*, return *+0*𝔽.
- 1. If _argument_ is *true*, return *1*𝔽.
- 1. If _argument_ is a String, return StringToNumber(_argument_).
- 1. Assert: _argument_ is an Object.
- 1. Let _primValue_ be ? ToPrimitive(_argument_, ~number~).
- 1. Assert: _primValue_ is not an Object.
- 1. Return ? ToNumber(_primValue_).
+ 1. If _arg_ is a Number, return _arg_.
+ 1. If _arg_ is either a Symbol or a BigInt, throw a *TypeError* exception.
+ 1. If _arg_ is *undefined*, return *NaN*.
+ 1. If _arg_ is either *null* or *false*, return *+0*𝔽.
+ 1. If _arg_ is *true*, return *1*𝔽.
+ 1. If _arg_ is a String, return StringToNumber(_arg_).
+ 1. Assert: _arg_ is an Object.
+ 1. Let _primitiveValue_ be ? ToPrimitive(_arg_, ~number~).
+ 1. Assert: _primitiveValue_ is not an Object.
+ 1. Return ? ToNumber(_primitiveValue_).
@@ -4974,13 +5224,13 @@ Syntax
StringToNumber (
- _str_: a String,
+ _string_: a String,
): a Number
- 1. Let _literal_ be ParseText(_str_, |StringNumericLiteral|).
+ 1. Let _literal_ be ParseText(_string_, |StringNumericLiteral|).
1. If _literal_ is a List of errors, return *NaN*.
1. Return the StringNumericValue of _literal_.
@@ -5024,20 +5274,20 @@ Runtime Semantics: StringNumericValue ( ): a Number
1. Else,
1. Let _b_ be 0.
1. Let _n_ be 0.
- 1. If |ExponentPart| is present, let _e_ be the MV of |ExponentPart|. Otherwise, let _e_ be 0.
+ 1. If |ExponentPart| is present, let _e_ be the MV of |ExponentPart|; else let _e_ be 0.
1. Return RoundMVResult((_a_ + (_b_ × 10-_n_)) × 10_e_).
StrUnsignedDecimalLiteral ::: `.` DecimalDigits ExponentPart?
1. Let _b_ be the MV of |DecimalDigits|.
- 1. If |ExponentPart| is present, let _e_ be the MV of |ExponentPart|. Otherwise, let _e_ be 0.
+ 1. If |ExponentPart| is present, let _e_ be the MV of |ExponentPart|; else let _e_ be 0.
1. Let _n_ be the number of code points in |DecimalDigits|.
1. Return RoundMVResult(_b_ × 10_e_ - _n_).
StrUnsignedDecimalLiteral ::: DecimalDigits ExponentPart?
1. Let _a_ be the MV of |DecimalDigits|.
- 1. If |ExponentPart| is present, let _e_ be the MV of |ExponentPart|. Otherwise, let _e_ be 0.
+ 1. If |ExponentPart| is present, let _e_ be the MV of |ExponentPart|; else let _e_ be 0.
1. Return RoundMVResult(_a_ × 10_e_).
@@ -5050,7 +5300,7 @@
- description
- - It converts _n_ to a Number in an implementation-defined manner. For the purposes of this abstract operation, a digit is significant if it is not zero or there is a non-zero digit to its left and there is a non-zero digit to its right. For the purposes of this abstract operation, "the mathematical value denoted by" a representation of a mathematical value is the inverse of "the decimal representation of" a mathematical value.
+ - It converts _n_ to a Number in an implementation-defined manner. For the purposes of this abstract operation, a digit is significant if it is not zero or there is a non-zero digit to its left and there is a non-zero digit to its right. For the purposes of this abstract operation, “the mathematical value denoted by” a representation of a mathematical value is the inverse of “the decimal representation of” a mathematical value.
1. If the decimal representation of _n_ has 20 or fewer significant digits, return 𝔽(_n_).
@@ -5066,15 +5316,15 @@
ToIntegerOrInfinity (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing either an integer, +∞, or -∞, or a throw completion
- description
- - It converts _argument_ to an integer representing its Number value with fractional part truncated, or to +∞ or -∞ when that Number value is infinite.
+ - It converts _arg_ to an integer representing its Number value with fractional part truncated, or to +∞ or -∞ when that Number value is infinite.
- 1. Let _number_ be ? ToNumber(_argument_).
+ 1. Let _number_ be ? ToNumber(_arg_).
1. If _number_ is one of *NaN*, *+0*𝔽, or *-0*𝔽, return 0.
1. If _number_ is *+∞*𝔽, return +∞.
1. If _number_ is *-∞*𝔽, return -∞.
@@ -5085,181 +5335,146 @@
+
+
+ ToFixedSizeInteger (
+ _int_: an integer, +∞, or -∞,
+ _signed_: ~unsigned~ or ~signed~,
+ _bitWidth_: a positive integer,
+ ): an integer
+
+
+ - description
+ - It maps _int_ to one of 2_bitWidth_ integers in the inclusive interval from 0 to 2_bitWidth_ - 1 (if _signed_ is ~unsigned~) or -2_bitWidth_ - 1 to 2_bitWidth_ - 1 - 1 (if _signed_ is ~signed~).
+
+
+ 1. If _int_ = +∞ or _int_ = -∞, return 0.
+ 1. Let _fixedInt_ be _int_ modulo 2_bitWidth_.
+ 1. NOTE: The following step does not change the two's complement representation of _fixedInt_.
+ 1. If _signed_ is ~signed~ and _fixedInt_ ≥ 2_bitWidth_ - 1, set _fixedInt_ to _fixedInt_ - 2_bitWidth_.
+ 1. Return _fixedInt_.
+
+
+ ToFixedSizeInteger is idempotent: for any ECMAScript language value _x_, ToFixedSizeInteger(ToFixedSizeInteger(_x_, _signed_, _bitWidth_), _signed_, _bitWidth_) is the same as ToFixedSizeInteger(_x_, _signed_, _bitWidth_). In fact, because +∞ and -∞ are mapped to 0, this invariant even survives inversion of _signed_ (e.g., ToFixedSizeInteger(ToFixedSizeInteger(_x_, ~signed~, 32), ~unsigned~, 32) is the same as ToFixedSizeInteger(_x_, ~unsigned~, 32)).
+
+
+
ToInt32 (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing an integral Number or a throw completion
- description
- - It converts _argument_ to one of 232 integral Number values in the inclusive interval from 𝔽(-231) to 𝔽(231 - 1).
+ - It converts _arg_ to one of 232 integral Number values in the inclusive interval from 𝔽(-231) to 𝔽(231 - 1), excluding *-0*𝔽.
- 1. Let _number_ be ? ToNumber(_argument_).
- 1. If _number_ is not finite or _number_ is either *+0*𝔽 or *-0*𝔽, return *+0*𝔽.
- 1. Let _int_ be truncate(ℝ(_number_)).
- 1. Let _int32bit_ be _int_ modulo 232.
- 1. If _int32bit_ ≥ 231, return 𝔽(_int32bit_ - 232); otherwise return 𝔽(_int32bit_).
+ 1. Let _int_ be ? ToIntegerOrInfinity(_arg_).
+ 1. Return 𝔽(ToFixedSizeInteger(_int_, ~signed~, 32)).
-
- Given the above definition of ToInt32:
-
- -
- The ToInt32 abstract operation is idempotent: if applied to a result that it produced, the second application leaves that value unchanged.
-
- -
- ToInt32(ToUint32(_x_)) is the same value as ToInt32(_x_) for all values of _x_. (It is to preserve this latter property that *+∞*𝔽 and *-∞*𝔽 are mapped to *+0*𝔽.)
-
- -
- ToInt32 maps *-0*𝔽 to *+0*𝔽.
-
-
-
ToUint32 (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing an integral Number or a throw completion
- description
- - It converts _argument_ to one of 232 integral Number values in the inclusive interval from *+0*𝔽 to 𝔽(232 - 1).
+ - It converts _arg_ to one of 232 integral Number values in the inclusive interval from *+0*𝔽 to 𝔽(232 - 1).
- 1. Let _number_ be ? ToNumber(_argument_).
- 1. If _number_ is not finite or _number_ is either *+0*𝔽 or *-0*𝔽, return *+0*𝔽.
- 1. Let _int_ be truncate(ℝ(_number_)).
- 1. Let _int32bit_ be _int_ modulo 232.
- 1. [id="step-touint32-return"] Return 𝔽(_int32bit_).
+ 1. Let _int_ be ? ToIntegerOrInfinity(_arg_).
+ 1. Return 𝔽(ToFixedSizeInteger(_int_, ~unsigned~, 32)).
-
- Given the above definition of ToUint32:
-
- -
- Step
- -
- The ToUint32 abstract operation is idempotent: if applied to a result that it produced, the second application leaves that value unchanged.
-
- -
- ToUint32(ToInt32(_x_)) is the same value as ToUint32(_x_) for all values of _x_. (It is to preserve this latter property that *+∞*𝔽 and *-∞*𝔽 are mapped to *+0*𝔽.)
-
- -
- ToUint32 maps *-0*𝔽 to *+0*𝔽.
-
-
-
ToInt16 (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing an integral Number or a throw completion
- description
- - It converts _argument_ to one of 216 integral Number values in the inclusive interval from 𝔽(-215) to 𝔽(215 - 1).
+ - It converts _arg_ to one of 216 integral Number values in the inclusive interval from 𝔽(-215) to 𝔽(215 - 1), excluding *-0*𝔽.
- 1. Let _number_ be ? ToNumber(_argument_).
- 1. If _number_ is not finite or _number_ is either *+0*𝔽 or *-0*𝔽, return *+0*𝔽.
- 1. Let _int_ be truncate(ℝ(_number_)).
- 1. Let _int16bit_ be _int_ modulo 216.
- 1. If _int16bit_ ≥ 215, return 𝔽(_int16bit_ - 216); otherwise return 𝔽(_int16bit_).
+ 1. Let _int_ be ? ToIntegerOrInfinity(_arg_).
+ 1. Return 𝔽(ToFixedSizeInteger(_int_, ~signed~, 16)).
ToUint16 (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing an integral Number or a throw completion
- description
- - It converts _argument_ to one of 216 integral Number values in the inclusive interval from *+0*𝔽 to 𝔽(216 - 1).
+ - It converts _arg_ to one of 216 integral Number values in the inclusive interval from *+0*𝔽 to 𝔽(216 - 1).
- 1. Let _number_ be ? ToNumber(_argument_).
- 1. If _number_ is not finite or _number_ is either *+0*𝔽 or *-0*𝔽, return *+0*𝔽.
- 1. Let _int_ be truncate(ℝ(_number_)).
- 1. [id="step-touint16-mod"] Let _int16bit_ be _int_ modulo 216.
- 1. Return 𝔽(_int16bit_).
+ 1. Let _int_ be ? ToIntegerOrInfinity(_arg_).
+ 1. Return 𝔽(ToFixedSizeInteger(_int_, ~unsigned~, 16)).
-
- Given the above definition of ToUint16:
-
- -
- The substitution of 216 for 232 in step
- -
- ToUint16 maps *-0*𝔽 to *+0*𝔽.
-
-
-
ToInt8 (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing an integral Number or a throw completion
- description
- - It converts _argument_ to one of 28 integral Number values in the inclusive interval from *-128*𝔽 to *127*𝔽.
+ - It converts _arg_ to one of 28 integral Number values in the inclusive interval from *-128*𝔽 to *127*𝔽, excluding *-0*𝔽.
- 1. Let _number_ be ? ToNumber(_argument_).
- 1. If _number_ is not finite or _number_ is either *+0*𝔽 or *-0*𝔽, return *+0*𝔽.
- 1. Let _int_ be truncate(ℝ(_number_)).
- 1. Let _int8bit_ be _int_ modulo 28.
- 1. If _int8bit_ ≥ 27, return 𝔽(_int8bit_ - 28); otherwise return 𝔽(_int8bit_).
+ 1. Let _int_ be ? ToIntegerOrInfinity(_arg_).
+ 1. Return 𝔽(ToFixedSizeInteger(_int_, ~signed~, 8)).
ToUint8 (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing an integral Number or a throw completion
- description
- - It converts _argument_ to one of 28 integral Number values in the inclusive interval from *+0*𝔽 to *255*𝔽.
+ - It converts _arg_ to one of 28 integral Number values in the inclusive interval from *+0*𝔽 to *255*𝔽.
- 1. Let _number_ be ? ToNumber(_argument_).
- 1. If _number_ is not finite or _number_ is either *+0*𝔽 or *-0*𝔽, return *+0*𝔽.
- 1. Let _int_ be truncate(ℝ(_number_)).
- 1. Let _int8bit_ be _int_ modulo 28.
- 1. Return 𝔽(_int8bit_).
+ 1. Let _int_ be ? ToIntegerOrInfinity(_arg_).
+ 1. Return 𝔽(ToFixedSizeInteger(_int_, ~unsigned~, 8)).
ToUint8Clamp (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing an integral Number or a throw completion
- description
- - It clamps and rounds _argument_ to one of 28 integral Number values in the inclusive interval from *+0*𝔽 to *255*𝔽.
+ - It clamps and rounds _arg_ to one of 28 integral Number values in the inclusive interval from *+0*𝔽 to *255*𝔽.
- 1. Let _number_ be ? ToNumber(_argument_).
+ 1. Let _number_ be ? ToNumber(_arg_).
1. If _number_ is *NaN*, return *+0*𝔽.
1. Let _mv_ be the extended mathematical value of _number_.
1. Let _clamped_ be the result of clamping _mv_ between 0 and 255.
1. Let _f_ be floor(_clamped_).
1. If _clamped_ < _f_ + 0.5, return 𝔽(_f_).
1. If _clamped_ > _f_ + 0.5, return 𝔽(_f_ + 1).
- 1. If _f_ is even, return 𝔽(_f_). Otherwise, return 𝔽(_f_ + 1).
+ 1. If _f_ is even, return 𝔽(_f_).
+ 1. Return 𝔽(_f_ + 1).
Unlike most other ECMAScript integer conversion operations, ToUint8Clamp rounds rather than truncates non-integral values. It also uses “round half to even” tie-breaking, which differs from the “round half up” tie-breaking of `Math.round` .
@@ -5269,27 +5484,29 @@
ToBigInt (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing a BigInt or a throw completion
- description
- - It converts _argument_ to a BigInt value, or throws if an implicit conversion from Number would be required.
+ - It converts _arg_ to a BigInt value, or throws if an implicit conversion from Number would be required.
- 1. Let _prim_ be ? ToPrimitive(_argument_, ~number~).
- 1. Return the value that _prim_ corresponds to in
-
-
- Argument Type
-
-
- Result
-
-
+
+
+
+ Argument Type
+
+
+ Result
+
+
+
Undefined
@@ -5311,7 +5528,7 @@
Boolean
- Return `1n` if _prim_ is *true* and `0n` if _prim_ is *false*.
+ Return `1n` if _primitive_ is *true* and `0n` if _primitive_ is *false*.
@@ -5319,7 +5536,7 @@
BigInt
- Return _prim_.
+ Return _primitive_.
@@ -5336,7 +5553,7 @@
- 1. Let _n_ be StringToBigInt(_prim_).
+ 1. Let _n_ be StringToBigInt(_primitive_).
1. If _n_ is *undefined*, throw a *SyntaxError* exception.
1. Return _n_.
@@ -5357,13 +5574,13 @@
StringToBigInt (
- _str_: a String,
+ _string_: a String,
): a BigInt or *undefined*
- 1. Let _literal_ be ParseText(_str_, |StringIntegerLiteral|).
+ 1. Let _literal_ be ParseText(_string_, |StringIntegerLiteral|).
1. If _literal_ is a List of errors, return *undefined*.
1. Let _mv_ be the MV of _literal_.
1. Assert: _mv_ is an integer.
@@ -5401,163 +5618,95 @@ Runtime Semantics: MV
ToBigInt64 (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing a BigInt or a throw completion
- description
- - It converts _argument_ to one of 264 BigInt values in the inclusive interval from ℤ(-263) to ℤ(263 - 1).
+ - It converts _arg_ to one of 264 BigInt values in the inclusive interval from ℤ(-263) to ℤ(263 - 1).
- 1. Let _n_ be ? ToBigInt(_argument_).
- 1. Let _int64bit_ be ℝ(_n_) modulo 264.
- 1. If _int64bit_ ≥ 263, return ℤ(_int64bit_ - 264); otherwise return ℤ(_int64bit_).
+ 1. Let _int_ be ℝ(? ToBigInt(_arg_)).
+ 1. Return ℤ(ToFixedSizeInteger(_int_, ~signed~, 64)).
ToBigUint64 (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing a BigInt or a throw completion
- description
- - It converts _argument_ to one of 264 BigInt values in the inclusive interval from *0*ℤ to ℤ(264 - 1).
+ - It converts _arg_ to one of 264 BigInt values in the inclusive interval from *0*ℤ to ℤ(264 - 1).
- 1. Let _n_ be ? ToBigInt(_argument_).
- 1. Let _int64bit_ be ℝ(_n_) modulo 264.
- 1. Return ℤ(_int64bit_).
+ 1. Let _int_ be ℝ(? ToBigInt(_arg_)).
+ 1. Return ℤ(ToFixedSizeInteger(_int_, ~unsigned~, 64)).
ToString (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing a String or a throw completion
- description
- - It converts _argument_ to a value of type String.
+ - It converts _arg_ to a value of type String.
- 1. If _argument_ is a String, return _argument_.
- 1. If _argument_ is a Symbol, throw a *TypeError* exception.
- 1. If _argument_ is *undefined*, return *"undefined"*.
- 1. If _argument_ is *null*, return *"null"*.
- 1. If _argument_ is *true*, return *"true"*.
- 1. If _argument_ is *false*, return *"false"*.
- 1. If _argument_ is a Number, return Number::toString(_argument_, 10).
- 1. If _argument_ is a BigInt, return BigInt::toString(_argument_, 10).
- 1. Assert: _argument_ is an Object.
- 1. Let _primValue_ be ? ToPrimitive(_argument_, ~string~).
- 1. Assert: _primValue_ is not an Object.
- 1. Return ? ToString(_primValue_).
+ 1. If _arg_ is a String, return _arg_.
+ 1. If _arg_ is a Symbol, throw a *TypeError* exception.
+ 1. If _arg_ is *undefined*, return *"undefined"*.
+ 1. If _arg_ is *null*, return *"null"*.
+ 1. If _arg_ is *true*, return *"true"*.
+ 1. If _arg_ is *false*, return *"false"*.
+ 1. If _arg_ is a Number, return Number::toString(_arg_, 10).
+ 1. If _arg_ is a BigInt, return BigInt::toString(_arg_, 10).
+ 1. Assert: _arg_ is an Object.
+ 1. Let _primitiveValue_ be ? ToPrimitive(_arg_, ~string~).
+ 1. Assert: _primitiveValue_ is not an Object.
+ 1. Return ? ToString(_primitiveValue_).
-
+
ToObject (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing an Object or a throw completion
- description
- - It converts _argument_ to a value of type Object according to
+ - It converts _arg_ to a value of type Object.
-
-
-
-
- Argument Type
-
-
- Result
-
-
-
-
- Undefined
-
-
- Throw a *TypeError* exception.
-
-
-
-
- Null
-
-
- Throw a *TypeError* exception.
-
-
-
-
- Boolean
-
-
- Return a new Boolean object whose [[BooleanData]] internal slot is set to _argument_. See
-
-
-
- Number
-
-
- Return a new Number object whose [[NumberData]] internal slot is set to _argument_. See
-
-
-
- String
-
-
- Return a new String object whose [[StringData]] internal slot is set to _argument_. See
-
-
-
- Symbol
-
-
- Return a new Symbol object whose [[SymbolData]] internal slot is set to _argument_. See
-
-
-
- BigInt
-
-
- Return a new BigInt object whose [[BigIntData]] internal slot is set to _argument_. See
-
-
-
- Object
-
-
- Return _argument_.
-
-
-
-
+
+ 1. If _arg_ is either *undefined* or *null*, throw a *TypeError* exception.
+ 1. If _arg_ is a Boolean, return a new Boolean object whose [[BooleanData]] internal slot is set to _arg_. See
ToPropertyKey (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing a property key or a throw completion
- description
- - It converts _argument_ to a value that can be used as a property key.
+ - It converts _arg_ to a value that can be used as a property key.
- 1. Let _key_ be ? ToPrimitive(_argument_, ~string~).
+ 1. Let _key_ be ? ToPrimitive(_arg_, ~string~).
1. If _key_ is a Symbol, then
1. Return _key_.
1. Return ! ToString(_key_).
@@ -5567,53 +5716,53 @@
ToLength (
- _argument_: an ECMAScript language value,
- ): either a normal completion containing an integral Number or a throw completion
+ _arg_: an ECMAScript language value,
+ ): either a normal completion containing a non-negative integral Number or a throw completion
- description
- - It clamps and truncates _argument_ to an integral Number suitable for use as the length of an array-like object.
+ - It clamps and truncates _arg_ to a non-negative integral Number suitable for use as the length of an array-like object.
- 1. Let _len_ be ? ToIntegerOrInfinity(_argument_).
- 1. If _len_ ≤ 0, return *+0*𝔽.
- 1. Return 𝔽(min(_len_, 253 - 1)).
+ 1. Let _length_ be ? ToIntegerOrInfinity(_arg_).
+ 1. If _length_ ≤ 0, return *+0*𝔽.
+ 1. Return 𝔽(min(_length_, 253 - 1)).
CanonicalNumericIndexString (
- _argument_: a String,
+ _arg_: a String,
): a Number or *undefined*
- description
- - If _argument_ is either *"-0"* or exactly matches the result of ToString(_n_) for some Number value _n_, it returns the respective Number value. Otherwise, it returns *undefined*.
+ - If _arg_ is either *"-0"* or exactly matches ToString(_n_) for some Number value _n_, it returns the respective Number value. Otherwise, it returns *undefined*.
- 1. If _argument_ is *"-0"*, return *-0*𝔽.
- 1. Let _n_ be ! ToNumber(_argument_).
- 1. If ! ToString(_n_) is _argument_, return _n_.
+ 1. If _arg_ is *"-0"*, return *-0*𝔽.
+ 1. Let _n_ be ! ToNumber(_arg_).
+ 1. If ! ToString(_n_) is _arg_, return _n_.
1. Return *undefined*.
- A canonical numeric string is any String value for which the CanonicalNumericIndexString abstract operation does not return *undefined*.
+ A canonical numeric string is any String for which the CanonicalNumericIndexString abstract operation does not return *undefined*.
ToIndex (
- _value_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing a non-negative integer or a throw completion
- description
- - It converts _value_ to an integer and returns that integer if it is non-negative and corresponds with an integer index. Otherwise, it throws an exception.
+ - It converts _arg_ to an integer and returns that integer if it is non-negative and corresponds with an integer index. Otherwise, it throws an exception.
- 1. Let _integer_ be ? ToIntegerOrInfinity(_value_).
- 1. If _integer_ is not in the inclusive interval from 0 to 253 - 1, throw a *RangeError* exception.
- 1. Return _integer_.
+ 1. Let _int_ be ? ToIntegerOrInfinity(_arg_).
+ 1. If _int_ is not in the inclusive interval from 0 to 253 - 1, throw a *RangeError* exception.
+ 1. Return _int_.
@@ -5621,108 +5770,36 @@
Testing and Comparison Operations
-
+
RequireObjectCoercible (
- _argument_: an ECMAScript language value,
- ): either a normal completion containing an ECMAScript language value or a throw completion
+ _arg_: an ECMAScript language value,
+ ): either a normal completion containing ~unused~ or a throw completion
- description
- - It throws an error if _argument_ is a value that cannot be converted to an Object using ToObject. It is defined by
+ - It throws an error if _arg_ is a value that cannot be converted to an Object using ToObject.
-
-
-
-
- Argument Type
-
-
- Result
-
-
-
-
- Undefined
-
-
- Throw a *TypeError* exception.
-
-
-
-
- Null
-
-
- Throw a *TypeError* exception.
-
-
-
-
- Boolean
-
-
- Return _argument_.
-
-
-
-
- Number
-
-
- Return _argument_.
-
-
-
-
- String
-
-
- Return _argument_.
-
-
-
-
- Symbol
-
-
- Return _argument_.
-
-
-
-
- BigInt
-
-
- Return _argument_.
-
-
-
-
- Object
-
-
- Return _argument_.
-
-
-
-
+
+ 1. If _arg_ is either *undefined* or *null*, throw a *TypeError* exception.
+ 1. Return ~unused~.
+
IsArray (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing a Boolean or a throw completion
- 1. If _argument_ is not an Object, return *false*.
- 1. If _argument_ is an Array exotic object, return *true*.
- 1. If _argument_ is a Proxy exotic object, then
- 1. Perform ? ValidateNonRevokedProxy(_argument_).
- 1. Let _proxyTarget_ be _argument_.[[ProxyTarget]].
+ 1. If _arg_ is not an Object, return *false*.
+ 1. If _arg_ is an Array exotic object, return *true*.
+ 1. If _arg_ is a Proxy exotic object, then
+ 1. Perform ? ValidateNonRevokedProxy(_arg_).
+ 1. Let _proxyTarget_ be _arg_.[[ProxyTarget]].
1. Return ? IsArray(_proxyTarget_).
1. Return *false*.
@@ -5731,16 +5808,16 @@
IsCallable (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): a Boolean
- description
- - It determines if _argument_ is a callable function with a [[Call]] internal method.
+ - It determines if _arg_ is a callable function with a [[Call]] internal method.
- 1. If _argument_ is not an Object, return *false*.
- 1. If _argument_ has a [[Call]] internal method, return *true*.
+ 1. If _arg_ is not an Object, return *false*.
+ 1. If _arg_ has a [[Call]] internal method, return *true*.
1. Return *false*.
@@ -5748,16 +5825,16 @@
IsConstructor (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): a Boolean
- description
- - It determines if _argument_ is a function object with a [[Construct]] internal method.
+ - It determines if _arg_ is a function object with a [[Construct]] internal method.
- 1. If _argument_ is not an Object, return *false*.
- 1. If _argument_ has a [[Construct]] internal method, return *true*.
+ 1. If _arg_ is not an Object, return *false*.
+ 1. If _arg_ has a [[Construct]] internal method, return *true*.
1. Return *false*.
@@ -5765,49 +5842,31 @@
IsExtensible (
- _O_: an Object,
+ _obj_: an Object,
): either a normal completion containing a Boolean or a throw completion
- description
- - It is used to determine whether additional properties can be added to _O_.
+ - It is used to determine whether additional properties can be added to _obj_.
- 1. Return ? _O_.[[IsExtensible]] ().
-
-
-
-
-
- IsIntegralNumber (
- _argument_: an ECMAScript language value,
- ): a Boolean
-
-
- - description
- - It determines if _argument_ is a finite integral Number value.
-
-
- 1. If _argument_ is not a Number, return *false*.
- 1. If _argument_ is not finite, return *false*.
- 1. If truncate(ℝ(_argument_)) ≠ ℝ(_argument_), return *false*.
- 1. Return *true*.
+ 1. Return ? _obj_.[[IsExtensible]]() .
IsRegExp (
- _argument_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): either a normal completion containing a Boolean or a throw completion
- 1. If _argument_ is not an Object, return *false*.
- 1. Let _matcher_ be ? Get(_argument_, @@match).
+ 1. If _arg_ is not an Object, return *false*.
+ 1. Let _matcher_ be ? Get(_arg_, %Symbol.match%).
1. If _matcher_ is not *undefined*, return ToBoolean(_matcher_).
- 1. If _argument_ has a [[RegExpMatcher]] internal slot, return *true*.
+ 1. If _arg_ has a [[RegExpMatcher]] internal slot, return *true*.
1. Return *false*.
@@ -5823,16 +5882,40 @@
- It interprets _string_ as a sequence of UTF-16 encoded code points, as described in
- 1. Let _len_ be the length of _string_.
+ 1. Let _length_ be the length of _string_.
1. Let _k_ be 0.
- 1. Repeat, while _k_ < _len_,
- 1. Let _cp_ be CodePointAt(_string_, _k_).
- 1. If _cp_.[[IsUnpairedSurrogate]] is *true*, return *false*.
- 1. Set _k_ to _k_ + _cp_.[[CodeUnitCount]].
+ 1. Repeat, while _k_ < _length_,
+ 1. Let _codePoint_ be CodePointAt(_string_, _k_).
+ 1. If _codePoint_.[[IsUnpairedSurrogate]] is *true*, return *false*.
+ 1. Set _k_ to _k_ + _codePoint_.[[CodeUnitCount]].
1. Return *true*.
+
+
+ SameType (
+ _x_: an ECMAScript language value,
+ _y_: an ECMAScript language value,
+ ): a Boolean
+
+
+ - description
+ - It determines whether or not the two arguments are the same type.
+
+
+ 1. If _x_ is *undefined* and _y_ is *undefined*, return *true*.
+ 1. If _x_ is *null* and _y_ is *null*, return *true*.
+ 1. If _x_ is a Boolean and _y_ is a Boolean, return *true*.
+ 1. If _x_ is a Number and _y_ is a Number, return *true*.
+ 1. If _x_ is a BigInt and _y_ is a BigInt, return *true*.
+ 1. If _x_ is a Symbol and _y_ is a Symbol, return *true*.
+ 1. If _x_ is a String and _y_ is a String, return *true*.
+ 1. If _x_ is an Object and _y_ is an Object, return *true*.
+ 1. Return *false*.
+
+
+
SameValue (
@@ -5845,7 +5928,7 @@
- It determines whether or not the two arguments are the same value.
- 1. If Type(_x_) is not Type(_y_), return *false*.
+ 1. If SameType(_x_, _y_) is *false*, return *false*.
1. If _x_ is a Number, then
1. Return Number::sameValue(_x_, _y_).
1. Return SameValueNonNumber(_x_, _y_).
@@ -5867,7 +5950,7 @@
- It determines whether or not the two arguments are the same value (ignoring the difference between *+0*𝔽 and *-0*𝔽).
- 1. If Type(_x_) is not Type(_y_), return *false*.
+ 1. If SameType(_x_, _y_) is *false*, return *false*.
1. If _x_ is a Number, then
1. Return Number::sameValueZero(_x_, _y_).
1. Return SameValueNonNumber(_x_, _y_).
@@ -5887,22 +5970,26 @@
- 1. Assert: Type(_x_) is Type(_y_).
- 1. If _x_ is either *null* or *undefined*, return *true*.
+ 1. Assert: SameType(_x_, _y_) is *true*.
+ 1. If _x_ is either *undefined* or *null*, return *true*.
1. If _x_ is a BigInt, then
1. Return BigInt::equal(_x_, _y_).
1. If _x_ is a String, then
- 1. If _x_ and _y_ have the same length and the same code units in the same positions, return *true*; otherwise, return *false*.
+ 1. If _x_ and _y_ have the same length and the same code units in the same positions, return *true*.
+ 1. Return *false*.
1. If _x_ is a Boolean, then
- 1. If _x_ and _y_ are both *true* or both *false*, return *true*; otherwise, return *false*.
+ 1. If _x_ is *true* and _y_ is *true*, return *true*.
+ 1. If _x_ is *false* and _y_ is *false*, return *true*.
+ 1. Return *false*.
1. NOTE: All other ECMAScript language values are compared by identity.
- 1. If _x_ is _y_, return *true*; otherwise, return *false*.
+ 1. If _x_ is _y_, return *true*.
+ 1. Return *false*.
For expository purposes, some cases are handled separately within this algorithm even if it is unnecessary to do so.
- The specifics of what "_x_ is _y_" means are detailed in
@@ -5911,15 +5998,15 @@
IsLessThan (
_x_: an ECMAScript language value,
_y_: an ECMAScript language value,
- _LeftFirst_: a Boolean,
+ _leftFirst_: a Boolean,
): either a normal completion containing either a Boolean or *undefined*, or a throw completion
- description
- - It provides the semantics for the comparison _x_ < _y_, returning *true*, *false*, or *undefined* (which indicates that at least one operand is *NaN*). The _LeftFirst_ flag is used to control the order in which operations with potentially visible side-effects are performed upon _x_ and _y_. It is necessary because ECMAScript specifies left to right evaluation of expressions. If _LeftFirst_ is *true*, the _x_ parameter corresponds to an expression that occurs to the left of the _y_ parameter's corresponding expression. If _LeftFirst_ is *false*, the reverse is the case and operations must be performed upon _y_ before _x_.
+ - It provides the semantics for the comparison _x_ < _y_, returning *true*, *false*, or *undefined* (which indicates that the operands could not be coerced to comparable values of the same numeric type). The _leftFirst_ flag is used to control the order in which operations with potentially visible side-effects are performed upon _x_ and _y_. It is necessary because ECMAScript specifies left to right evaluation of expressions. If _leftFirst_ is *true*, the _x_ parameter corresponds to an expression that occurs to the left of the _y_ parameter's corresponding expression. If _leftFirst_ is *false*, the reverse is the case and operations must be performed upon _y_ before _x_.
- 1. If _LeftFirst_ is *true*, then
+ 1. If _leftFirst_ is *true*, then
1. Let _px_ be ? ToPrimitive(_x_, ~number~).
1. Let _py_ be ? ToPrimitive(_y_, ~number~).
1. Else,
@@ -5934,30 +6021,29 @@
1. Let _cy_ be the numeric value of the code unit at index _i_ within _py_.
1. If _cx_ < _cy_, return *true*.
1. If _cx_ > _cy_, return *false*.
- 1. If _lx_ < _ly_, return *true*. Otherwise, return *false*.
- 1. Else,
- 1. If _px_ is a BigInt and _py_ is a String, then
- 1. Let _ny_ be StringToBigInt(_py_).
- 1. If _ny_ is *undefined*, return *undefined*.
- 1. Return BigInt::lessThan(_px_, _ny_).
- 1. If _px_ is a String and _py_ is a BigInt, then
- 1. Let _nx_ be StringToBigInt(_px_).
- 1. If _nx_ is *undefined*, return *undefined*.
- 1. Return BigInt::lessThan(_nx_, _py_).
- 1. NOTE: Because _px_ and _py_ are primitive values, evaluation order is not important.
- 1. Let _nx_ be ? ToNumeric(_px_) .
- 1. Let _ny_ be ? ToNumeric(_py_) .
- 1. If Type(_nx_) is Type(_ny_), then
- 1. If _nx_ is a Number, then
- 1. Return Number::lessThan(_nx_, _ny_).
- 1. Else,
- 1. Assert: _nx_ is a BigInt.
- 1. Return BigInt::lessThan(_nx_, _ny_).
- 1. Assert: _nx_ is a BigInt and _ny_ is a Number, or _nx_ is a Number and _ny_ is a BigInt.
- 1. If _nx_ or _ny_ is *NaN*, return *undefined*.
- 1. If _nx_ is *-∞*𝔽 or _ny_ is *+∞*𝔽, return *true*.
- 1. If _nx_ is *+∞*𝔽 or _ny_ is *-∞*𝔽, return *false*.
- 1. If ℝ(_nx_) < ℝ(_ny_), return *true*; otherwise return *false*.
+ 1. If _lx_ < _ly_, return *true*.
+ 1. Return *false*.
+ 1. If _px_ is a BigInt and _py_ is a String, then
+ 1. Let _ny_ be StringToBigInt(_py_).
+ 1. If _ny_ is *undefined*, return *undefined*.
+ 1. Return BigInt::lessThan(_px_, _ny_).
+ 1. If _px_ is a String and _py_ is a BigInt, then
+ 1. Let _nx_ be StringToBigInt(_px_).
+ 1. If _nx_ is *undefined*, return *undefined*.
+ 1. Return BigInt::lessThan(_nx_, _py_).
+ 1. NOTE: Because _px_ and _py_ are primitive values, evaluation order is not important.
+ 1. Let _nx_ be ? ToNumeric(_px_) .
+ 1. Let _ny_ be ? ToNumeric(_py_) .
+ 1. If SameType(_nx_, _ny_) is *true*, then
+ 1. If _nx_ is a Number, return Number::lessThan(_nx_, _ny_).
+ 1. Assert: _nx_ is a BigInt.
+ 1. Return BigInt::lessThan(_nx_, _ny_).
+ 1. Assert: _nx_ is a BigInt and _ny_ is a Number, or _nx_ is a Number and _ny_ is a BigInt.
+ 1. If _nx_ is *NaN* or _ny_ is *NaN*, return *undefined*.
+ 1. If _nx_ is *-∞*𝔽 or _ny_ is *+∞*𝔽, return *true*.
+ 1. If _nx_ is *+∞*𝔽 or _ny_ is *-∞*𝔽, return *false*.
+ 1. If ℝ(_nx_) < ℝ(_ny_), return *true*.
+ 1. Return *false*.
Step
@@ -5967,7 +6053,7 @@
-
+
IsLooselyEqual (
_x_: an ECMAScript language value,
@@ -5979,11 +6065,13 @@
- It provides the semantics for the `==` operator.
- 1. If Type(_x_) is Type(_y_), then
+ 1. If SameType(_x_, _y_) is *true*, then
1. Return IsStrictlyEqual(_x_, _y_).
1. If _x_ is *null* and _y_ is *undefined*, return *true*.
1. If _x_ is *undefined* and _y_ is *null*, return *true*.
- 1. [id="step-abstract-equality-comparison-web-compat-insertion-point"] NOTE: This step is replaced in section
1. If _x_ is an Object and _y_ is either a String, a Number, a BigInt, or a Symbol, return ! IsLooselyEqual(? ToPrimitive(_x_), _y_).
1. If _x_ is a BigInt and _y_ is a Number, or if _x_ is a Number and _y_ is a BigInt, then
1. If _x_ is not finite or _y_ is not finite, return *false*.
- 1. If ℝ(_x_) = ℝ(_y_), return *true*; otherwise return *false*.
+ 1. If ℝ(_x_) = ℝ(_y_), return *true*.
+ 1. Return *false*.
1. Return *false*.
@@ -6014,7 +6103,7 @@
- It provides the semantics for the `===` operator.
- 1. If Type(_x_) is not Type(_y_), return *false*.
+ 1. If SameType(_x_, _y_) is *false*, return *false*.
1. If _x_ is a Number, then
1. Return Number::equal(_x_, _y_).
1. Return SameValueNonNumber(_x_, _y_).
@@ -6040,7 +6129,10 @@
+ 1. Set _internalSlotsList_ to the list-concatenation of _internalSlotsList_ and « [[PrivateElements]] ».
1. Let _obj_ be a newly created object with an internal slot for each name in _internalSlotsList_.
+ 1. NOTE: As described in
Get (
- _O_: an Object,
- _P_: a property key,
+ _obj_: an Object,
+ _propertyKey_: a property key,
): either a normal completion containing an ECMAScript language value or a throw completion
@@ -6065,15 +6157,15 @@
- It is used to retrieve the value of a specific property of an object.
- 1. Return ? _O_.[[Get]] (_P_, _O_).
+ 1. Return ? _obj_.[[Get]](_propertyKey_, _obj_) .
GetV (
- _V_: an ECMAScript language value,
- _P_: a property key,
+ _value_: an ECMAScript language value,
+ _propertyKey_: a property key,
): either a normal completion containing an ECMAScript language value or a throw completion
@@ -6081,27 +6173,27 @@
- It is used to retrieve the value of a specific property of an ECMAScript language value. If the value is not an object, the property lookup is performed using a wrapper object appropriate for the type of the value.
- 1. Let _O_ be ? ToObject(_V_).
- 1. Return ? _O_.[[Get]] (_P_, _V_).
+ 1. Let _obj_ be ? ToObject(_value_).
+ 1. Return ? _obj_.[[Get]](_propertyKey_, _value_) .
Set (
- _O_: an Object,
- _P_: a property key,
- _V_: an ECMAScript language value,
- _Throw_: a Boolean,
+ _obj_: an Object,
+ _propertyKey_: a property key,
+ _value_: an ECMAScript language value,
+ _throw_: a Boolean,
): either a normal completion containing ~unused~ or a throw completion
- description
- - It is used to set the value of a specific property of an object. _V_ is the new value for the property.
+ - It is used to set the value of a specific property of an object. _value_ is the new value for the property.
- 1. Let _success_ be ? _O_.[[Set]] (_P_, _V_, _O_).
- 1. If _success_ is *false* and _Throw_ is *true*, throw a *TypeError* exception.
+ 1. Let _success_ be ? _obj_.[[Set]](_propertyKey_, _value_, _obj_) .
+ 1. If _success_ is *false* and _throw_ is *true*, throw a *TypeError* exception.
1. Return ~unused~.
@@ -6109,9 +6201,9 @@
CreateDataProperty (
- _O_: an Object,
- _P_: a property key,
- _V_: an ECMAScript language value,
+ _obj_: an Object,
+ _propertyKey_: a property key,
+ _value_: an ECMAScript language value,
): either a normal completion containing a Boolean or a throw completion
@@ -6119,20 +6211,20 @@
- It is used to create a new own property of an object.
- 1. Let _newDesc_ be the PropertyDescriptor { [[Value]]: _V_, [[Writable]]: *true*, [[Enumerable]]: *true*, [[Configurable]]: *true* }.
- 1. Return ? _O_.[[DefineOwnProperty]] (_P_, _newDesc_).
+ 1. Let _newDesc_ be the PropertyDescriptor { [[Value]]: _value_, [[Writable]]: *true*, [[Enumerable]]: *true*, [[Configurable]]: *true* }.
+ 1. Return ? _obj_.[[DefineOwnProperty]](_propertyKey_, _newDesc_) .
- This abstract operation creates a property whose attributes are set to the same defaults used for properties created by the ECMAScript language assignment operator. Normally, the property will not already exist. If it does exist and is not configurable or if _O_ is not extensible, [[DefineOwnProperty]] will return *false*.
+ This abstract operation creates a property whose attributes are set to the same defaults used for properties created by the ECMAScript language assignment operator. Normally, the property will not already exist. If it does exist and is not configurable or if _obj_ is not extensible, [[DefineOwnProperty]] will return *false*.
CreateDataPropertyOrThrow (
- _O_: an Object,
- _P_: a property key,
- _V_: an ECMAScript language value,
+ _obj_: an Object,
+ _propertyKey_: a property key,
+ _value_: an ECMAScript language value,
): either a normal completion containing ~unused~ or a throw completion
@@ -6140,21 +6232,21 @@
- It is used to create a new own property of an object. It throws a *TypeError* exception if the requested property update cannot be performed.
- 1. Let _success_ be ? CreateDataProperty(_O_, _P_, _V_).
+ 1. Let _success_ be ? CreateDataProperty(_obj_, _propertyKey_, _value_).
1. If _success_ is *false*, throw a *TypeError* exception.
1. Return ~unused~.
- This abstract operation creates a property whose attributes are set to the same defaults used for properties created by the ECMAScript language assignment operator. Normally, the property will not already exist. If it does exist and is not configurable or if _O_ is not extensible, [[DefineOwnProperty]] will return *false* causing this operation to throw a *TypeError* exception.
+ This abstract operation creates a property whose attributes are set to the same defaults used for properties created by the ECMAScript language assignment operator. Normally, the property will not already exist. If it does exist and is not configurable or if _obj_ is not extensible, [[DefineOwnProperty]] will return *false* causing this operation to throw a *TypeError* exception.
CreateNonEnumerableDataPropertyOrThrow (
- _O_: an Object,
- _P_: a property key,
- _V_: an ECMAScript language value,
+ _obj_: an Object,
+ _propertyKey_: a property key,
+ _value_: an ECMAScript language value,
): ~unused~
@@ -6162,9 +6254,9 @@
- It is used to create a new non-enumerable own property of an ordinary object.
- 1. Assert: _O_ is an ordinary, extensible object with no non-configurable properties.
- 1. Let _newDesc_ be the PropertyDescriptor { [[Value]]: _V_, [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *true* }.
- 1. Perform ! DefinePropertyOrThrow(_O_, _P_, _newDesc_).
+ 1. Assert: _obj_ is an ordinary, extensible object with no non-configurable properties.
+ 1. Let _newDesc_ be the PropertyDescriptor { [[Value]]: _value_, [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *true* }.
+ 1. Perform ! DefinePropertyOrThrow(_obj_, _propertyKey_, _newDesc_).
1. Return ~unused~.
@@ -6175,9 +6267,9 @@
DefinePropertyOrThrow (
- _O_: an Object,
- _P_: a property key,
- _desc_: a Property Descriptor,
+ _obj_: an Object,
+ _propertyKey_: a property key,
+ _propertyDesc_: a Property Descriptor,
): either a normal completion containing ~unused~ or a throw completion
@@ -6185,7 +6277,7 @@
- It is used to call the [[DefineOwnProperty]] internal method of an object in a manner that will throw a *TypeError* exception if the requested property update cannot be performed.
- 1. Let _success_ be ? _O_.[[DefineOwnProperty]] (_P_, _desc_).
+ 1. Let _success_ be ? _obj_.[[DefineOwnProperty]](_propertyKey_, _propertyDesc_) .
1. If _success_ is *false*, throw a *TypeError* exception.
1. Return ~unused~.
@@ -6194,8 +6286,8 @@
DeletePropertyOrThrow (
- _O_: an Object,
- _P_: a property key,
+ _obj_: an Object,
+ _propertyKey_: a property key,
): either a normal completion containing ~unused~ or a throw completion
@@ -6203,7 +6295,7 @@
- It is used to remove a specific own property of an object. It throws an exception if the property is not configurable.
- 1. Let _success_ be ? _O_.[[Delete]] (_P_).
+ 1. Let _success_ be ? _obj_.[[Delete]](_propertyKey_) .
1. If _success_ is *false*, throw a *TypeError* exception.
1. Return ~unused~.
@@ -6212,8 +6304,8 @@
GetMethod (
- _V_: an ECMAScript language value,
- _P_: a property key,
+ _value_: an ECMAScript language value,
+ _propertyKey_: a property key,
): either a normal completion containing either a function object or *undefined*, or a throw completion
@@ -6221,7 +6313,7 @@
- It is used to get the value of a specific property of an ECMAScript language value when the value of the property is expected to be a function.
- 1. Let _func_ be ? GetV(_V_, _P_).
+ 1. Let _func_ be ? GetV(_value_, _propertyKey_).
1. If _func_ is either *undefined* or *null*, return *undefined*.
1. If IsCallable(_func_) is *false*, throw a *TypeError* exception.
1. Return _func_.
@@ -6231,8 +6323,8 @@
HasProperty (
- _O_: an Object,
- _P_: a property key,
+ _obj_: an Object,
+ _propertyKey_: a property key,
): either a normal completion containing a Boolean or a throw completion
@@ -6240,15 +6332,15 @@
- It is used to determine whether an object has a property with the specified property key. The property may be either own or inherited.
- 1. Return ? _O_.[[HasProperty]] (_P_).
+ 1. Return ? _obj_.[[HasProperty]](_propertyKey_) .
HasOwnProperty (
- _O_: an Object,
- _P_: a property key,
+ _obj_: an Object,
+ _propertyKey_: a property key,
): either a normal completion containing a Boolean or a throw completion
@@ -6256,8 +6348,8 @@
- It is used to determine whether an object has an own property with the specified property key.
- 1. Let _desc_ be ? _O_.[[GetOwnProperty]] (_P_).
- 1. If _desc_ is *undefined*, return *false*.
+ 1. Let _propertyDesc_ be ? _obj_.[[GetOwnProperty]](_propertyKey_) .
+ 1. If _propertyDesc_ is *undefined*, return *false*.
1. Return *true*.
@@ -6265,38 +6357,38 @@
Call (
- _F_: an ECMAScript language value,
- _V_: an ECMAScript language value,
- optional _argumentsList_: a List of ECMAScript language values,
+ _func_: an ECMAScript language value,
+ _thisValue_: an ECMAScript language value,
+ optional _argList_: a List of ECMAScript language values,
): either a normal completion containing an ECMAScript language value or a throw completion
- description
- - It is used to call the [[Call]] internal method of a function object. _F_ is the function object, _V_ is an ECMAScript language value that is the *this* value of the [[Call]], and _argumentsList_ is the value passed to the corresponding argument of the internal method. If _argumentsList_ is not present, a new empty List is used as its value.
+ - It is used to call the [[Call]] internal method of a function object. _func_ is the function object, _thisValue_ is an ECMAScript language value that is the *this* value of the [[Call]], and _argList_ is the value passed to the corresponding argument of the internal method. If _argList_ is not present, a new empty List is used as its value.
- 1. If _argumentsList_ is not present, set _argumentsList_ to a new empty List.
- 1. If IsCallable(_F_) is *false*, throw a *TypeError* exception.
- 1. Return ? _F_.[[Call]] (_V_, _argumentsList_).
+ 1. If _argList_ is not present, set _argList_ to a new empty List.
+ 1. If IsCallable(_func_) is *false*, throw a *TypeError* exception.
+ 1. Return ? _func_.[[Call]](_thisValue_, _argList_) .
Construct (
- _F_: a constructor,
- optional _argumentsList_: a List of ECMAScript language values,
+ _ctor_: a constructor,
+ optional _argList_: a List of ECMAScript language values,
optional _newTarget_: a constructor,
): either a normal completion containing an Object or a throw completion
- description
- - It is used to call the [[Construct]] internal method of a function object. _argumentsList_ and _newTarget_ are the values to be passed as the corresponding arguments of the internal method. If _argumentsList_ is not present, a new empty List is used as its value. If _newTarget_ is not present, _F_ is used as its value.
+ - It is used to call the [[Construct]] internal method of a function object. _argList_ and _newTarget_ are the values to be passed as the corresponding arguments of the internal method. If _argList_ is not present, a new empty List is used as its value. If _newTarget_ is not present, _ctor_ is used as its value.
- 1. If _newTarget_ is not present, set _newTarget_ to _F_.
- 1. If _argumentsList_ is not present, set _argumentsList_ to a new empty List.
- 1. Return ? _F_.[[Construct]] (_argumentsList_, _newTarget_).
+ 1. If _newTarget_ is not present, set _newTarget_ to _ctor_.
+ 1. If _argList_ is not present, set _argList_ to a new empty List.
+ 1. Return ? _ctor_.[[Construct]](_argList_, _newTarget_) .
If _newTarget_ is not present, this operation is equivalent to: `new F(...argumentsList)`
@@ -6306,7 +6398,7 @@
SetIntegrityLevel (
- _O_: an Object,
+ _obj_: an Object,
_level_: ~sealed~ or ~frozen~,
): either a normal completion containing a Boolean or a throw completion
@@ -6315,22 +6407,22 @@
- It is used to fix the set of own properties of an object.
- 1. Let _status_ be ? _O_.[[PreventExtensions]]().
+ 1. Let _status_ be ? _obj_.[[PreventExtensions]]().
1. If _status_ is *false*, return *false*.
- 1. Let _keys_ be ? _O_.[[OwnPropertyKeys]]().
+ 1. Let _keys_ be ? _obj_.[[OwnPropertyKeys]]().
1. If _level_ is ~sealed~, then
- 1. For each element _k_ of _keys_, do
- 1. Perform ? DefinePropertyOrThrow(_O_, _k_, PropertyDescriptor { [[Configurable]]: *false* }).
+ 1. For each element _key_ of _keys_, do
+ 1. Perform ? DefinePropertyOrThrow(_obj_, _key_, PropertyDescriptor { [[Configurable]]: *false* }).
1. Else,
1. Assert: _level_ is ~frozen~.
- 1. For each element _k_ of _keys_, do
- 1. Let _currentDesc_ be ? _O_.[[GetOwnProperty]] (_k_).
+ 1. For each element _key_ of _keys_, do
+ 1. Let _currentDesc_ be ? _obj_.[[GetOwnProperty]](_key_) .
1. If _currentDesc_ is not *undefined*, then
1. If IsAccessorDescriptor(_currentDesc_) is *true*, then
- 1. Let _desc_ be the PropertyDescriptor { [[Configurable]]: *false* }.
+ 1. Let _propertyDesc_ be the PropertyDescriptor { [[Configurable]]: *false* }.
1. Else,
- 1. Let _desc_ be the PropertyDescriptor { [[Configurable]]: *false*, [[Writable]]: *false* }.
- 1. Perform ? DefinePropertyOrThrow(_O_, _k_, _desc_).
+ 1. Let _propertyDesc_ be the PropertyDescriptor { [[Configurable]]: *false*, [[Writable]]: *false* }.
+ 1. Perform ? DefinePropertyOrThrow(_obj_, _key_, _propertyDesc_).
1. Return *true*.
@@ -6338,7 +6430,7 @@
TestIntegrityLevel (
- _O_: an Object,
+ _obj_: an Object,
_level_: ~sealed~ or ~frozen~,
): either a normal completion containing a Boolean or a throw completion
@@ -6347,12 +6439,12 @@
- It is used to determine if the set of own properties of an object are fixed.
- 1. Let _extensible_ be ? IsExtensible(_O_).
+ 1. Let _extensible_ be ? IsExtensible(_obj_).
1. If _extensible_ is *true*, return *false*.
1. NOTE: If the object is extensible, none of its properties are examined.
- 1. Let _keys_ be ? _O_.[[OwnPropertyKeys]]().
- 1. For each element _k_ of _keys_, do
- 1. Let _currentDesc_ be ? _O_.[[GetOwnProperty]] (_k_).
+ 1. Let _keys_ be ? _obj_.[[OwnPropertyKeys]]().
+ 1. For each element _key_ of _keys_, do
+ 1. Let _currentDesc_ be ? _obj_.[[GetOwnProperty]](_key_) .
1. If _currentDesc_ is not *undefined*, then
1. If _currentDesc_.[[Configurable]] is *true*, return *false*.
1. If _level_ is ~frozen~ and IsDataDescriptor(_currentDesc_) is *true*, then
@@ -6374,8 +6466,8 @@
1. Let _array_ be ! ArrayCreate(0).
1. Let _n_ be 0.
- 1. For each element _e_ of _elements_, do
- 1. Perform ! CreateDataPropertyOrThrow(_array_, ! ToString(𝔽(_n_)), _e_).
+ 1. For each element _element_ of _elements_, do
+ 1. Perform ! CreateDataPropertyOrThrow(_array_, ! ToString(𝔽(_n_)), _element_).
1. Set _n_ to _n_ + 1.
1. Return _array_.
@@ -6407,23 +6499,23 @@
CreateListFromArrayLike (
_obj_: an ECMAScript language value,
- optional _elementTypes_: a List of names of ECMAScript Language Types,
+ optional _validElementTypes_: ~all~ or ~property-key~,
): either a normal completion containing a List of ECMAScript language values or a throw completion
- description
- - It is used to create a List value whose elements are provided by the indexed properties of _obj_. _elementTypes_ contains the names of ECMAScript Language Types that are allowed for element values of the List that is created.
+ - It is used to create a List value whose elements are provided by the indexed properties of _obj_. _validElementTypes_ indicates the types of values that are allowed as elements.
- 1. If _elementTypes_ is not present, set _elementTypes_ to « Undefined, Null, Boolean, String, Symbol, Number, BigInt, Object ».
+ 1. If _validElementTypes_ is not present, set _validElementTypes_ to ~all~.
1. If _obj_ is not an Object, throw a *TypeError* exception.
- 1. Let _len_ be ? LengthOfArrayLike(_obj_).
+ 1. Let _length_ be ? LengthOfArrayLike(_obj_).
1. Let _list_ be a new empty List.
1. Let _index_ be 0.
- 1. Repeat, while _index_ < _len_,
+ 1. Repeat, while _index_ < _length_,
1. Let _indexName_ be ! ToString(𝔽(_index_)).
1. Let _next_ be ? Get(_obj_, _indexName_).
- 1. If _elementTypes_ does not contain Type(_next_), throw a *TypeError* exception.
+ 1. If _validElementTypes_ is ~property-key~ and _next_ is not a property key, throw a *TypeError* exception.
1. Append _next_ to _list_.
1. Set _index_ to _index_ + 1.
1. Return _list_.
@@ -6433,67 +6525,67 @@
Invoke (
- _V_: an ECMAScript language value,
- _P_: a property key,
- optional _argumentsList_: a List of ECMAScript language values,
+ _value_: an ECMAScript language value,
+ _propertyKey_: a property key,
+ optional _argList_: a List of ECMAScript language values,
): either a normal completion containing an ECMAScript language value or a throw completion
- description
- - It is used to call a method property of an ECMAScript language value. _V_ serves as both the lookup point for the property and the *this* value of the call. _argumentsList_ is the list of arguments values passed to the method. If _argumentsList_ is not present, a new empty List is used as its value.
+ - It is used to call a method property of an ECMAScript language value. _value_ serves as both the lookup point for the property and the *this* value of the call. _argList_ is the list of arguments values passed to the method. If _argList_ is not present, a new empty List is used as its value.
- 1. If _argumentsList_ is not present, set _argumentsList_ to a new empty List.
- 1. Let _func_ be ? GetV(_V_, _P_).
- 1. Return ? Call(_func_, _V_, _argumentsList_).
+ 1. If _argList_ is not present, set _argList_ to a new empty List.
+ 1. Let _func_ be ? GetV(_value_, _propertyKey_).
+ 1. Return ? Call(_func_, _value_, _argList_).
OrdinaryHasInstance (
- _C_: an ECMAScript language value,
- _O_: an ECMAScript language value,
+ _ctor_: an ECMAScript language value,
+ _instance_: an ECMAScript language value,
): either a normal completion containing a Boolean or a throw completion
- description
- - It implements the default algorithm for determining if _O_ inherits from the instance object inheritance path provided by _C_.
+ - It implements the default algorithm for determining if _instance_ inherits from the instance object inheritance path provided by _ctor_.
- 1. If IsCallable(_C_) is *false*, return *false*.
- 1. If _C_ has a [[BoundTargetFunction]] internal slot, then
- 1. Let _BC_ be _C_.[[BoundTargetFunction]].
- 1. Return ? InstanceofOperator(_O_, _BC_).
- 1. If _O_ is not an Object, return *false*.
- 1. Let _P_ be ? Get(_C_, *"prototype"*).
- 1. If _P_ is not an Object, throw a *TypeError* exception.
+ 1. If IsCallable(_ctor_) is *false*, return *false*.
+ 1. If _ctor_ has a [[BoundTargetFunction]] internal slot, then
+ 1. Let _boundCtor_ be _ctor_.[[BoundTargetFunction]].
+ 1. Return ? InstanceofOperator(_instance_, _boundCtor_).
+ 1. If _instance_ is not an Object, return *false*.
+ 1. Let _proto_ be ? Get(_ctor_, *"prototype"*).
+ 1. If _proto_ is not an Object, throw a *TypeError* exception.
1. Repeat,
- 1. Set _O_ to ? _O_.[[GetPrototypeOf]] ().
- 1. If _O_ is *null*, return *false*.
- 1. If SameValue(_P_, _O_) is *true*, return *true*.
+ 1. Set _instance_ to ? _instance_.[[GetPrototypeOf]]() .
+ 1. If _instance_ is *null*, return *false*.
+ 1. If SameValue(_proto_, _instance_) is *true*, return *true*.
SpeciesConstructor (
- _O_: an Object,
- _defaultConstructor_: a constructor,
+ _obj_: an Object,
+ _defaultCtor_: a constructor,
): either a normal completion containing a constructor or a throw completion
- description
- - It is used to retrieve the constructor that should be used to create new objects that are derived from _O_. _defaultConstructor_ is the constructor to use if a constructor @@species property cannot be found starting from _O_.
+ - It is used to retrieve the constructor that should be used to create new objects that are derived from _obj_. _defaultCtor_ is the constructor to use if a constructor %Symbol.species% property cannot be found starting from _obj_.
- 1. Let _C_ be ? Get(_O_, *"constructor"*).
- 1. If _C_ is *undefined*, return _defaultConstructor_.
- 1. If _C_ is not an Object, throw a *TypeError* exception.
- 1. Let _S_ be ? Get(_C_, @@species).
- 1. If _S_ is either *undefined* or *null*, return _defaultConstructor_.
- 1. If IsConstructor(_S_) is *true*, return _S_.
+ 1. Let _ctor_ be ? Get(_obj_, *"constructor"*).
+ 1. If _ctor_ is *undefined*, return _defaultCtor_.
+ 1. If _ctor_ is not an Object, throw a *TypeError* exception.
+ 1. Let _species_ be ? Get(_ctor_, %Symbol.species%).
+ 1. If _species_ is either *undefined* or *null*, return _defaultCtor_.
+ 1. If IsConstructor(_species_) is *true*, return _species_.
1. Throw a *TypeError* exception.
@@ -6501,23 +6593,23 @@
EnumerableOwnProperties (
- _O_: an Object,
+ _obj_: an Object,
_kind_: ~key~, ~value~, or ~key+value~,
): either a normal completion containing a List of ECMAScript language values or a throw completion
- 1. Let _ownKeys_ be ? _O_.[[OwnPropertyKeys]] ().
+ 1. Let _ownKeys_ be ? _obj_.[[OwnPropertyKeys]]() .
1. Let _results_ be a new empty List.
1. For each element _key_ of _ownKeys_, do
1. If _key_ is a String, then
- 1. Let _desc_ be ? _O_.[[GetOwnProperty]] (_key_).
- 1. If _desc_ is not *undefined* and _desc_.[[Enumerable]] is *true*, then
+ 1. Let _propertyDesc_ be ? _obj_.[[GetOwnProperty]](_key_) .
+ 1. If _propertyDesc_ is not *undefined* and _propertyDesc_.[[Enumerable]] is *true*, then
1. If _kind_ is ~key~, then
1. Append _key_ to _results_.
1. Else,
- 1. Let _value_ be ? Get(_O_, _key_).
+ 1. Let _value_ be ? Get(_obj_, _key_).
1. If _kind_ is ~value~, then
1. Append _value_ to _results_.
1. Else,
@@ -6531,25 +6623,26 @@
GetFunctionRealm (
- _obj_: a function object,
+ _func_: a function object,
): either a normal completion containing a Realm Record or a throw completion
- 1. If _obj_ has a [[Realm]] internal slot, then
- 1. Return _obj_.[[Realm]].
- 1. If _obj_ is a bound function exotic object, then
- 1. Let _boundTargetFunction_ be _obj_.[[BoundTargetFunction]].
- 1. Return ? GetFunctionRealm(_boundTargetFunction_).
- 1. If _obj_ is a Proxy exotic object, then
- 1. Perform ? ValidateNonRevokedProxy(_obj_).
- 1. Let _proxyTarget_ be _obj_.[[ProxyTarget]].
+ 1. If _func_ has a [[Realm]] internal slot, then
+ 1. Return _func_.[[Realm]].
+ 1. If _func_ is a bound function exotic object, then
+ 1. Let _boundTargetFunc_ be _func_.[[BoundTargetFunction]].
+ 1. Return ? GetFunctionRealm(_boundTargetFunc_).
+ 1. If _func_ is a Proxy exotic object, then
+ 1. Perform ? ValidateNonRevokedProxy(_func_).
+ 1. Let _proxyTarget_ be _func_.[[ProxyTarget]].
+ 1. Assert: _proxyTarget_ is a function object.
1. Return ? GetFunctionRealm(_proxyTarget_).
1. [id="step-getfunctionrealm-default-return"] Return the current Realm Record.
- Step
+ Step
@@ -6566,17 +6659,17 @@
1. If _source_ is either *undefined* or *null*, return ~unused~.
1. Let _from_ be ! ToObject(_source_).
- 1. Let _keys_ be ? _from_.[[OwnPropertyKeys]] ().
+ 1. Let _keys_ be ? _from_.[[OwnPropertyKeys]]() .
1. For each element _nextKey_ of _keys_, do
1. Let _excluded_ be *false*.
- 1. For each element _e_ of _excludedItems_, do
- 1. If SameValue(_e_, _nextKey_) is *true*, then
+ 1. For each element _element_ of _excludedItems_, do
+ 1. If SameValue(_element_, _nextKey_) is *true*, then
1. Set _excluded_ to *true*.
1. If _excluded_ is *false*, then
- 1. Let _desc_ be ? _from_.[[GetOwnProperty]] (_nextKey_).
- 1. If _desc_ is not *undefined* and _desc_.[[Enumerable]] is *true*, then
- 1. Let _propValue_ be ? Get(_from_, _nextKey_).
- 1. Perform ! CreateDataPropertyOrThrow(_target_, _nextKey_, _propValue_).
+ 1. Let _propertyDesc_ be ? _from_.[[GetOwnProperty]](_nextKey_) .
+ 1. If _propertyDesc_ is not *undefined* and _propertyDesc_.[[Enumerable]] is *true*, then
+ 1. Let _propertyValue_ be ? Get(_from_, _nextKey_).
+ 1. Perform ! CreateDataPropertyOrThrow(_target_, _nextKey_, _propertyValue_).
1. Return ~unused~.
@@ -6587,15 +6680,15 @@
PrivateElementFind (
- _O_: an Object,
- _P_: a Private Name,
+ _obj_: an Object,
+ _privateName_: a Private Name,
): a PrivateElement or ~empty~
- 1. If _O_.[[PrivateElements]] contains a PrivateElement _pe_ such that _pe_.[[Key]] is _P_, then
- 1. Return _pe_.
+ 1. If _obj_.[[PrivateElements]] contains a PrivateElement _entry_ such that _entry_.[[Key]] is _privateName_, then
+ 1. Return _entry_.
1. Return ~empty~.
@@ -6603,8 +6696,8 @@
PrivateFieldAdd (
- _O_: an Object,
- _P_: a Private Name,
+ _obj_: an Object,
+ _privateName_: a Private Name,
_value_: an ECMAScript language value,
): either a normal completion containing ~unused~ or a throw completion
@@ -6612,10 +6705,10 @@
1. If the host is a web browser, then
- 1. Perform ? HostEnsureCanAddPrivateElement(_O_).
- 1. Let _entry_ be PrivateElementFind(_O_, _P_).
+ 1. Perform ? HostEnsureCanAddPrivateElement(_obj_).
+ 1. Let _entry_ be PrivateElementFind(_obj_, _privateName_).
1. If _entry_ is not ~empty~, throw a *TypeError* exception.
- 1. Append PrivateElement { [[Key]]: _P_, [[Kind]]: ~field~, [[Value]]: _value_ } to _O_.[[PrivateElements]].
+ 1. Append PrivateElement { [[Key]]: _privateName_, [[Kind]]: ~field~, [[Value]]: _value_ } to _obj_.[[PrivateElements]].
1. Return ~unused~.
@@ -6623,7 +6716,7 @@
PrivateMethodOrAccessorAdd (
- _O_: an Object,
+ _obj_: an Object,
_method_: a PrivateElement,
): either a normal completion containing ~unused~ or a throw completion
@@ -6632,10 +6725,10 @@
1. Assert: _method_.[[Kind]] is either ~method~ or ~accessor~.
1. If the host is a web browser, then
- 1. Perform ? HostEnsureCanAddPrivateElement(_O_).
- 1. Let _entry_ be PrivateElementFind(_O_, _method_.[[Key]]).
+ 1. Perform ? HostEnsureCanAddPrivateElement(_obj_).
+ 1. Let _entry_ be PrivateElementFind(_obj_, _method_.[[Key]]).
1. If _entry_ is not ~empty~, throw a *TypeError* exception.
- 1. Append _method_ to _O_.[[PrivateElements]].
+ 1. Append _method_ to _obj_.[[PrivateElements]].
1. Return ~unused~.
@@ -6646,7 +6739,7 @@
HostEnsureCanAddPrivateElement (
- _O_: an Object,
+ _obj_: an Object,
): either a normal completion containing ~unused~ or a throw completion
@@ -6655,7 +6748,7 @@
An implementation of HostEnsureCanAddPrivateElement must conform to the following requirements:
- - If _O_ is not a host-defined exotic object, this abstract operation must return NormalCompletion(~unused~) and perform no other steps.
+ - If _obj_ is not a host-defined exotic object, this abstract operation must return NormalCompletion(~unused~) and perform no other steps.
- Any two calls of this abstract operation with the same argument must return the same kind of Completion Record.
The default implementation of HostEnsureCanAddPrivateElement is to return NormalCompletion(~unused~).
@@ -6665,46 +6758,45 @@
PrivateGet (
- _O_: an Object,
- _P_: a Private Name,
+ _obj_: an Object,
+ _privateName_: a Private Name,
): either a normal completion containing an ECMAScript language value or a throw completion
- 1. Let _entry_ be PrivateElementFind(_O_, _P_).
+ 1. Let _entry_ be PrivateElementFind(_obj_, _privateName_).
1. If _entry_ is ~empty~, throw a *TypeError* exception.
1. If _entry_.[[Kind]] is either ~field~ or ~method~, then
1. Return _entry_.[[Value]].
1. Assert: _entry_.[[Kind]] is ~accessor~.
- 1. If _entry_.[[Get]] is *undefined*, throw a *TypeError* exception.
- 1. Let _getter_ be _entry_.[[Get]].
- 1. Return ? Call(_getter_, _O_).
+ 1. If _entry_.[[Getter]] is *undefined*, throw a *TypeError* exception.
+ 1. Let _getter_ be _entry_.[[Getter]].
+ 1. Return ? Call(_getter_, _obj_).
PrivateSet (
- _O_: an Object,
- _P_: a Private Name,
+ _obj_: an Object,
+ _privateName_: a Private Name,
_value_: an ECMAScript language value,
): either a normal completion containing ~unused~ or a throw completion
- 1. Let _entry_ be PrivateElementFind(_O_, _P_).
+ 1. Let _entry_ be PrivateElementFind(_obj_, _privateName_).
1. If _entry_ is ~empty~, throw a *TypeError* exception.
+ 1. If _entry_.[[Kind]] is ~method~, throw a *TypeError* exception.
1. If _entry_.[[Kind]] is ~field~, then
1. Set _entry_.[[Value]] to _value_.
- 1. Else if _entry_.[[Kind]] is ~method~, then
- 1. Throw a *TypeError* exception.
1. Else,
1. Assert: _entry_.[[Kind]] is ~accessor~.
- 1. If _entry_.[[Set]] is *undefined*, throw a *TypeError* exception.
- 1. Let _setter_ be _entry_.[[Set]].
- 1. Perform ? Call(_setter_, _O_, « _value_ »).
+ 1. If _entry_.[[Setter]] is *undefined*, throw a *TypeError* exception.
+ 1. Let _setter_ be _entry_.[[Setter]].
+ 1. Perform ? Call(_setter_, _obj_, « _value_ »).
1. Return ~unused~.
@@ -6737,19 +6829,19 @@
InitializeInstanceElements (
- _O_: an Object,
- _constructor_: an ECMAScript function object,
+ _obj_: an Object,
+ _ctor_: an ECMAScript function object or a built-in function object,
): either a normal completion containing ~unused~ or a throw completion
- 1. Let _methods_ be the value of _constructor_.[[PrivateMethods]].
+ 1. Let _methods_ be _ctor_.[[PrivateMethods]].
1. For each PrivateElement _method_ of _methods_, do
- 1. Perform ? PrivateMethodOrAccessorAdd(_O_, _method_).
- 1. Let _fields_ be the value of _constructor_.[[Fields]].
+ 1. Perform ? PrivateMethodOrAccessorAdd(_obj_, _method_).
+ 1. Let _fields_ be _ctor_.[[Fields]].
1. For each element _fieldRecord_ of _fields_, do
- 1. Perform ? DefineField(_O_, _fieldRecord_).
+ 1. Perform ? DefineField(_obj_, _fieldRecord_).
1. Return ~unused~.
@@ -6765,10 +6857,10 @@
- 1. For each Record { [[Key]], [[Elements]] } _g_ of _groups_, do
- 1. If SameValue(_g_.[[Key]], _key_) is *true*, then
+ 1. For each Record { [[Key]], [[Elements]] } _group_ of _groups_, do
+ 1. If SameValue(_group_.[[Key]], _key_) is *true*, then
1. Assert: Exactly one element of _groups_ meets this criterion.
- 1. Append _value_ to _g_.[[Elements]].
+ 1. Append _value_ to _group_.[[Elements]].
1. Return ~unused~.
1. Let _group_ be the Record { [[Key]]: _key_, [[Elements]]: « _value_ » }.
1. Append _group_ to _groups_.
@@ -6780,15 +6872,15 @@
GroupBy (
_items_: an ECMAScript language value,
- _callbackfn_: an ECMAScript language value,
- _keyCoercion_: ~property~ or ~zero~,
+ _callback_: an ECMAScript language value,
+ _keyCoercion_: ~property~ or ~collection~,
): either a normal completion containing a List of Records with fields [[Key]] (an ECMAScript language value) and [[Elements]] (a List of ECMAScript language values), or a throw completion
1. Perform ? RequireObjectCoercible(_items_).
- 1. If IsCallable(_callbackfn_) is *false*, throw a *TypeError* exception.
+ 1. If IsCallable(_callback_) is *false*, throw a *TypeError* exception.
1. Let _groups_ be a new empty List.
1. Let _iteratorRecord_ be ? GetIterator(_items_, ~sync~).
1. Let _k_ be 0.
@@ -6800,18 +6892,61 @@
1. If _next_ is ~done~, then
1. Return _groups_.
1. Let _value_ be _next_.
- 1. Let _key_ be Completion(Call(_callbackfn_, *undefined*, « _value_, 𝔽(_k_) »)).
+ 1. Let _key_ be Completion(Call(_callback_, *undefined*, « _value_, 𝔽(_k_) »)).
1. IfAbruptCloseIterator(_key_, _iteratorRecord_).
1. If _keyCoercion_ is ~property~, then
1. Set _key_ to Completion(ToPropertyKey(_key_)).
1. IfAbruptCloseIterator(_key_, _iteratorRecord_).
1. Else,
- 1. Assert: _keyCoercion_ is ~zero~.
- 1. If _key_ is *-0*𝔽, set _key_ to *+0*𝔽.
+ 1. Assert: _keyCoercion_ is ~collection~.
+ 1. Set _key_ to CanonicalizeKeyedCollectionKey(_key_).
1. Perform AddValueToKeyedGroup(_groups_, _key_, _value_).
1. Set _k_ to _k_ + 1.
+
+
+
+ GetOptionsObject (
+ _options_: an ECMAScript language value,
+ ): either a normal completion containing an Object or a throw completion
+
+
+
+
+ 1. If _options_ is *undefined*, then
+ 1. Return OrdinaryObjectCreate(*null*).
+ 1. If _options_ is an Object, then
+ 1. Return _options_.
+ 1. Throw a *TypeError* exception.
+
+
+
+
+
+ SetterThatIgnoresPrototypeProperties (
+ _thisValue_: an ECMAScript language value,
+ _home_: an Object,
+ _propertyKey_: a property key,
+ _value_: an ECMAScript language value,
+ ): either a normal completion containing ~unused~ or a throw completion
+
+
+
+
+ 1. If _thisValue_ is not an Object, then
+ 1. Throw a *TypeError* exception.
+ 1. If SameValue(_thisValue_, _home_) is *true*, then
+ 1. NOTE: Throwing here emulates assignment to a non-writable data property on the _home_ object in strict mode code.
+ 1. Throw a *TypeError* exception.
+ 1. Let _propertyDesc_ be ? _thisValue_.[[GetOwnProperty]](_propertyKey_).
+ 1. If _propertyDesc_ is *undefined*, then
+ 1. Perform ? CreateDataPropertyOrThrow(_thisValue_, _propertyKey_, _value_).
+ 1. Else,
+ 1. Perform ? Set(_thisValue_, _propertyKey_, _value_, *true*).
+ 1. Return ~unused~.
+
+
@@ -6820,21 +6955,23 @@ Operations on Iterator Objects
Iterator Records
- An Iterator Record is a Record value used to encapsulate an Iterator or AsyncIterator along with the `next` method.
+ An Iterator Record is a Record used to encapsulate an iterator or async iterator along with the `next` method.
Iterator Records have the fields listed in
-
-
- Field Name
-
-
- Value
-
-
- Meaning
-
-
+
+
+
+ Field Name
+
+
+ Value
+
+
+ Meaning
+
+
+
[[Iterator]]
@@ -6843,7 +6980,7 @@ Iterator Records
an Object
- An object that conforms to the Iterator or AsyncIterator interface.
+ An object that conforms to the iterator interface or the async iterator interface.
@@ -6872,6 +7009,21 @@ Iterator Records
+
+
+ GetIteratorDirect (
+ _obj_: an Object,
+ ): either a normal completion containing an Iterator Record or a throw completion
+
+
+
+
+ 1. Let _nextMethod_ be ? Get(_obj_, *"next"*).
+ 1. Let _iteratorRecord_ be the Iterator Record { [[Iterator]]: _obj_, [[NextMethod]]: _nextMethod_, [[Done]]: *false* }.
+ 1. Return _iteratorRecord_.
+
+
+
GetIteratorFromMethod (
@@ -6884,9 +7036,7 @@
1. Let _iterator_ be ? Call(_method_, _obj_).
1. If _iterator_ is not an Object, throw a *TypeError* exception.
- 1. Let _nextMethod_ be ? Get(_iterator_, *"next"*).
- 1. Let _iteratorRecord_ be the Iterator Record { [[Iterator]]: _iterator_, [[NextMethod]]: _nextMethod_, [[Done]]: *false* }.
- 1. Return _iteratorRecord_.
+ 1. Return ? GetIteratorDirect(_iterator_).
@@ -6901,19 +7051,43 @@
1. If _kind_ is ~async~, then
- 1. Let _method_ be ? GetMethod(_obj_, @@asyncIterator).
+ 1. Let _method_ be ? GetMethod(_obj_, %Symbol.asyncIterator%).
1. If _method_ is *undefined*, then
- 1. Let _syncMethod_ be ? GetMethod(_obj_, @@iterator).
+ 1. Let _syncMethod_ be ? GetMethod(_obj_, %Symbol.iterator%).
1. If _syncMethod_ is *undefined*, throw a *TypeError* exception.
1. Let _syncIteratorRecord_ be ? GetIteratorFromMethod(_obj_, _syncMethod_).
1. Return CreateAsyncFromSyncIterator(_syncIteratorRecord_).
1. Else,
- 1. Let _method_ be ? GetMethod(_obj_, @@iterator).
+ 1. Let _method_ be ? GetMethod(_obj_, %Symbol.iterator%).
1. If _method_ is *undefined*, throw a *TypeError* exception.
1. Return ? GetIteratorFromMethod(_obj_, _method_).
+
+
+ GetIteratorFlattenable (
+ _obj_: an ECMAScript language value,
+ _primitiveHandling_: ~iterate-string-primitives~ or ~reject-primitives~,
+ ): either a normal completion containing an Iterator Record or a throw completion
+
+
+
+
+ 1. If _obj_ is not an Object, then
+ 1. If _primitiveHandling_ is ~reject-primitives~, throw a *TypeError* exception.
+ 1. Assert: _primitiveHandling_ is ~iterate-string-primitives~.
+ 1. If _obj_ is not a String, throw a *TypeError* exception.
+ 1. Let _method_ be ? GetMethod(_obj_, %Symbol.iterator%).
+ 1. If _method_ is *undefined*, then
+ 1. Let _iterator_ be _obj_.
+ 1. Else,
+ 1. Let _iterator_ be ? Call(_method_, _obj_).
+ 1. If _iterator_ is not an Object, throw a *TypeError* exception.
+ 1. Return ? GetIteratorDirect(_iterator_).
+
+
+
IteratorNext (
@@ -6942,26 +7116,26 @@
IteratorComplete (
- _iterResult_: an Object,
+ _iteratorResult_: an Object,
): either a normal completion containing a Boolean or a throw completion
- 1. Return ToBoolean(? Get(_iterResult_, *"done"*)).
+ 1. Return ToBoolean(? Get(_iteratorResult_, *"done"*)).
IteratorValue (
- _iterResult_: an Object,
+ _iteratorResult_: an Object,
): either a normal completion containing an ECMAScript language value or a throw completion
- 1. Return ? Get(_iterResult_, *"value"*).
+ 1. Return ? Get(_iteratorResult_, *"value"*).
@@ -7036,6 +7210,24 @@
+
+
+ IteratorCloseAll (
+ _iterators_: a List of Iterator Records,
+ _completion_: a Completion Record,
+ ): a Completion Record
+
+
+ - skip global checks
+ - true
+
+
+ 1. For each element _iterator_ of _iterators_, in reverse List order, do
+ 1. Set _completion_ to Completion(IteratorClose(_iterator_, _completion_)).
+ 1. Return ? _completion_.
+
+
+
IfAbruptCloseIterator ( _value_, _iteratorRecord_ )
IfAbruptCloseIterator is a shorthand for a sequence of algorithm steps that use an Iterator Record. An algorithm step of the form:
@@ -7046,7 +7238,21 @@ IfAbruptCloseIterator ( _value_, _iteratorRecord_ )
1. Assert: _value_ is a Completion Record.
1. If _value_ is an abrupt completion, return ? IteratorClose(_iteratorRecord_, _value_).
- 1. Else, set _value_ to ! _value_.
+ 1. Set _value_ to ! _value_.
+
+
+
+
+ IfAbruptCloseIterators ( _value_, _iteratorRecords_ )
+ IfAbruptCloseIterators is a shorthand for a sequence of algorithm steps that use a list of Iterator Records. An algorithm step of the form:
+
+ 1. IfAbruptCloseIterators(_value_, _iteratorRecords_).
+
+ means the same thing as:
+
+ 1. Assert: _value_ is a Completion Record.
+ 1. If _value_ is an abrupt completion, return ? IteratorCloseAll(_iteratorRecords_, _value_).
+ 1. Set _value_ to ! _value_.
@@ -7077,16 +7283,30 @@
+
+ IfAbruptCloseAsyncIterator ( _value_, _iteratorRecord_ )
+ IfAbruptCloseAsyncIterator is a shorthand for a sequence of algorithm steps that use an Iterator Record. An algorithm step of the form:
+
+ 1. IfAbruptCloseAsyncIterator(_value_, _iteratorRecord_).
+
+ means the same thing as:
+
+ 1. Assert: _value_ is a Completion Record.
+ 1. If _value_ is an abrupt completion, return ? AsyncIteratorClose(_iteratorRecord_, _value_).
+ 1. Set _value_ to ! _value_.
+
+
+
- CreateIterResultObject (
+ CreateIteratorResultObject (
_value_: an ECMAScript language value,
_done_: a Boolean,
- ): an Object that conforms to the IteratorResult interface
+ ): an Object that conforms to the IteratorResult interface
- description
- - It creates an object that conforms to the IteratorResult interface.
+ - It creates an object that conforms to the IteratorResult interface.
1. Let _obj_ be OrdinaryObjectCreate(%Object.prototype%).
@@ -7104,15 +7324,15 @@
- description
- - It creates an Iterator (
+ - It creates an Iterator Record whose [[NextMethod]] returns the successive elements of _list_.
1. Let _closure_ be a new Abstract Closure with no parameters that captures _list_ and performs the following steps when called:
- 1. For each element _E_ of _list_, do
- 1. Perform ? GeneratorYield(CreateIterResultObject(_E_, *false*)).
+ 1. For each element _value_ of _list_, do
+ 1. Perform ? GeneratorYield(CreateIteratorResultObject(_value_, *false*)).
1. Return NormalCompletion(*undefined*).
- 1. Let _iterator_ be CreateIteratorFromClosure(_closure_, ~empty~, %IteratorPrototype%).
- 1. Return the Iterator Record { [[Iterator]]: _iterator_, [[NextMethod]]: %GeneratorFunction.prototype.prototype.next%, [[Done]]: *false* }.
+ 1. Let _iterator_ be CreateIteratorFromClosure(_closure_, ~empty~, %Iterator.prototype%).
+ 1. Return the Iterator Record { [[Iterator]]: _iterator_, [[NextMethod]]: %GeneratorPrototype.next%, [[Done]]: *false* }.
The list iterator object is never directly accessible to ECMAScript code.
@@ -7137,6 +7357,186 @@
+
+
+ Operations on Disposable Objects
+ See Common Resource Management Interfaces (
+
+
+ DisposableResource Records
+ A DisposableResource Record is a Record value used to encapsulate a disposable object along with the method used to dispose the object. DisposableResource Records are produced by the CreateDisposableResource abstract operation.
+ DisposableResource Records have the fields listed in
+
+
+
+
+ Field Name
+
+
+ Value
+
+
+ Meaning
+
+
+
+
+ [[ResourceValue]]
+
+
+ an Object or *undefined*
+
+
+ The value to be disposed.
+
+
+
+
+ [[Kind]]
+
+
+ ~sync-dispose~ or ~async-dispose~
+
+
+ Indicates whether the resource was added by a `using` declaration or DisposableStack object (~sync-dispose~) or by an `await using` declaration or AsyncDisposableStack object (~async-dispose~).
+
+
+
+
+ [[DisposeMethod]]
+
+
+ a function object or *undefined*
+
+
+ A function object that will be called with [[ResourceValue]] as its *this* value when the resource is disposed.
+
+
+
+
+
+
+
+
+ AddDisposableResource (
+ _disposableResourceStack_: a List of DisposableResource Records,
+ _value_: an ECMAScript language value,
+ _kind_: ~sync-dispose~ or ~async-dispose~,
+ optional _method_: a function object,
+ ): either a normal completion containing ~unused~ or a throw completion
+
+
+
+
+ 1. If _method_ is present, then
+ 1. Assert: _value_ is *undefined*.
+ 1. Let _resource_ be ? CreateDisposableResource(*undefined*, _kind_, _method_).
+ 1. Else,
+ 1. If _value_ is either *null* or *undefined* and _kind_ is ~sync-dispose~, return ~unused~.
+ 1. NOTE: When _value_ is either *null* or *undefined* and _kind_ is ~async-dispose~, we record that the resource was evaluated to ensure we will still perform an Await when resources are later disposed.
+ 1. Let _resource_ be ? CreateDisposableResource(_value_, _kind_).
+ 1. Append _resource_ to _disposableResourceStack_.
+ 1. Return ~unused~.
+
+
+
+
+
+ CreateDisposableResource (
+ _value_: an ECMAScript language value,
+ _kind_: ~sync-dispose~ or ~async-dispose~,
+ optional _method_: a function object,
+ ): either a normal completion containing a DisposableResource Record or a throw completion
+
+
+
+
+ 1. If _method_ is not present, then
+ 1. If _value_ is either *null* or *undefined*, then
+ 1. Set _value_ to *undefined*.
+ 1. Set _method_ to *undefined*.
+ 1. Else,
+ 1. Set _method_ to ? GetDisposeMethod(_value_, _kind_).
+ 1. If _method_ is *undefined*, throw a *TypeError* exception.
+ 1. Return the DisposableResource Record { [[ResourceValue]]: _value_, [[Kind]]: _kind_, [[DisposeMethod]]: _method_ }.
+
+
+
+
+
+ GetDisposeMethod (
+ _value_: an ECMAScript language value,
+ _kind_: ~sync-dispose~ or ~async-dispose~,
+ ): either a normal completion containing either a function object or *undefined*, or a throw completion
+
+
+
+
+ 1. If _value_ is not an Object, throw a *TypeError* exception.
+ 1. If _kind_ is ~sync-dispose~, return ? GetMethod(_value_, %Symbol.dispose%).
+ 1. Assert: _kind_ is ~async-dispose~.
+ 1. Let _asyncMethod_ be ? GetMethod(_value_, %Symbol.asyncDispose%).
+ 1. If _asyncMethod_ is not *undefined*, return _asyncMethod_.
+ 1. Let _syncMethod_ be ? GetMethod(_value_, %Symbol.dispose%).
+ 1. If _syncMethod_ is *undefined*, return *undefined*.
+ 1. Let _closure_ be a new Abstract Closure with no parameters that captures _syncMethod_ and performs the following steps when called:
+ 1. Let _obj_ be the *this* value.
+ 1. Let _promiseCapability_ be ! NewPromiseCapability(%Promise%).
+ 1. Let _result_ be Completion(Call(_syncMethod_, _obj_)).
+ 1. IfAbruptRejectPromise(_result_, _promiseCapability_).
+ 1. Perform ! Call(_promiseCapability_.[[Resolve]], *undefined*, « *undefined* »).
+ 1. Return _promiseCapability_.[[Promise]].
+ 1. NOTE: This function is not observable to user code. It is used to ensure that a Promise returned from a synchronous `%Symbol.dispose%` method will not be awaited and that a synchronous exception will be translated to a rejected Promise.
+ 1. Return CreateBuiltinFunction(_closure_, 0, *""*, « »).
+
+
+
+
+
+ DisposeResources (
+ _disposableResourceStack_: a List of DisposableResource Records,
+ _completion_: either a normal completion containing either an ECMAScript language value or ~empty~, or an abrupt completion,
+ ): either a normal completion containing either an ECMAScript language value or ~empty~, or an abrupt completion
+
+
+
+
+ 1. Let _needsAwait_ be *false*.
+ 1. Let _hasAwaited_ be *false*.
+ 1. Let _outputCompletion_ be _completion_.
+ 1. For each element _resource_ of _disposableResourceStack_, in reverse List order, do
+ 1. Let _value_ be _resource_.[[ResourceValue]].
+ 1. Let _kind_ be _resource_.[[Kind]].
+ 1. Let _method_ be _resource_.[[DisposeMethod]].
+ 1. If _kind_ is ~sync-dispose~, _needsAwait_ is *true*, and _hasAwaited_ is *false*, then
+ 1. Perform ! Await(*undefined*).
+ 1. Set _needsAwait_ to *false*.
+ 1. If _method_ is not *undefined*, then
+ 1. Let _result_ be Completion(Call(_method_, _value_)).
+ 1. If _result_ is a normal completion and _kind_ is ~async-dispose~, then
+ 1. Set _result_ to Completion(Await(_result_.[[Value]])).
+ 1. Set _hasAwaited_ to *true*.
+ 1. If _result_ is a throw completion, then
+ 1. If _outputCompletion_ is a throw completion, then
+ 1. Set _result_ to _result_.[[Value]].
+ 1. Let _suppressed_ be _outputCompletion_.[[Value]].
+ 1. Let _error_ be a newly created *SuppressedError* object.
+ 1. Perform CreateNonEnumerableDataPropertyOrThrow(_error_, *"error"*, _result_).
+ 1. Perform CreateNonEnumerableDataPropertyOrThrow(_error_, *"suppressed"*, _suppressed_).
+ 1. Set _outputCompletion_ to ThrowCompletion(_error_).
+ 1. Else,
+ 1. Set _outputCompletion_ to _result_.
+ 1. Else,
+ 1. Assert: _kind_ is ~async-dispose~.
+ 1. Set _needsAwait_ to *true*.
+ 1. NOTE: This can only indicate a case where either *null* or *undefined* was the initialized value of an `await using` declaration.
+ 1. If _needsAwait_ is *true* and _hasAwaited_ is *false*, then
+ 1. Perform ! Await(*undefined*).
+ 1. NOTE: At this point _disposableResourceStack_ will never be used again. The contents of _disposableResourceStack_ can be discarded in implementations, such as by garbage collection.
+ 1. Return ? _outputCompletion_.
+
+
+
@@ -7150,7 +7550,7 @@ Runtime Semantics: Evaluation ( ): a Completion Record
- user-code
- The definitions for this operation are distributed over the "ECMAScript Language" sections of this specification. Each definition appears after the defining occurrence of the relevant productions.
+ The definitions for this operation are distributed over the “ECMAScript Language” sections of this specification. Each definition appears after the defining occurrence of the relevant productions.
@@ -7180,6 +7580,16 @@ Static Semantics: BoundNames ( ): a List of Strings
1. Return the BoundNames of |BindingList|.
+
+ UsingDeclaration :
+ `using` BindingList `;`
+
+ AwaitUsingDeclaration :
+ CoverAwaitExpressionAndAwaitUsingDeclarationHead BindingList `;`
+
+
+ 1. Return the BoundNames of |BindingList|.
+
BindingList : BindingList `,` LexicalBinding
1. Let _names1_ be the BoundNames of |BindingList|.
@@ -7340,11 +7750,11 @@ Static Semantics: BoundNames ( ): a List of Strings
1. Let _head_ be the |AsyncArrowHead| that is covered by |CoverCallExpressionAndAsyncArrowHead|.
1. Return the BoundNames of _head_.
- ImportDeclaration : `import` ImportClause FromClause `;`
+ ImportDeclaration : `import` ImportClause FromClause WithClause? `;`
1. Return the BoundNames of |ImportClause|.
- ImportDeclaration : `import` ModuleSpecifier `;`
+ ImportDeclaration : `import` ModuleSpecifier WithClause? `;`
1. Return a new empty List.
@@ -7376,7 +7786,7 @@ Static Semantics: BoundNames ( ): a List of Strings
ExportDeclaration :
- `export` ExportFromClause FromClause `;`
+ `export` ExportFromClause FromClause WithClause? `;`
`export` NamedExports `;`
@@ -7392,15 +7802,15 @@ Static Semantics: BoundNames ( ): a List of Strings
ExportDeclaration : `export` `default` HoistableDeclaration
- 1. Let _declarationNames_ be the BoundNames of |HoistableDeclaration|.
- 1. If _declarationNames_ does not include the element *"\*default\*"*, append *"\*default\*"* to _declarationNames_.
- 1. Return _declarationNames_.
+ 1. Let _declNames_ be the BoundNames of |HoistableDeclaration|.
+ 1. If _declNames_ does not include the element *"\*default\*"*, append *"\*default\*"* to _declNames_.
+ 1. Return _declNames_.
ExportDeclaration : `export` `default` ClassDeclaration
- 1. Let _declarationNames_ be the BoundNames of |ClassDeclaration|.
- 1. If _declarationNames_ does not include the element *"\*default\*"*, append *"\*default\*"* to _declarationNames_.
- 1. Return _declarationNames_.
+ 1. Let _declNames_ be the BoundNames of |ClassDeclaration|.
+ 1. If _declNames_ does not include the element *"\*default\*"*, append *"\*default\*"* to _declNames_.
+ 1. Return _declNames_.
ExportDeclaration : `export` `default` AssignmentExpression `;`
@@ -7454,6 +7864,16 @@ Static Semantics: IsConstantDeclaration ( ): a Boolean
1. Return *true*.
+
+ UsingDeclaration :
+ `using` BindingList `;`
+
+ AwaitUsingDeclaration :
+ CoverAwaitExpressionAndAwaitUsingDeclarationHead BindingList `;`
+
+
+ 1. Return *true*.
+
FunctionDeclaration :
`function` BindingIdentifier `(` FormalParameters `)` `{` FunctionBody `}`
@@ -7496,6 +7916,124 @@ Static Semantics: IsConstantDeclaration ( ): a Boolean
+
+ Static Semantics: IsUsingDeclaration ( ): a Boolean
+
+
+ LexicalDeclaration : LetOrConst BindingList `;`
+
+ 1. Return *false*.
+
+
+ UsingDeclaration :
+ `using` BindingList `;`
+
+ AwaitUsingDeclaration :
+ CoverAwaitExpressionAndAwaitUsingDeclarationHead BindingList `;`
+
+
+ 1. Return *true*.
+
+ ForDeclaration : LetOrConst ForBinding
+
+ 1. Return *false*.
+
+
+ ForDeclaration :
+ `using` ForBinding
+ `await` `using` ForBinding
+
+
+ 1. Return *true*.
+
+
+ FunctionDeclaration :
+ `function` BindingIdentifier `(` FormalParameters `)` `{` FunctionBody `}`
+ `function` `(` FormalParameters `)` `{` FunctionBody `}`
+
+ GeneratorDeclaration :
+ `function` `*` BindingIdentifier `(` FormalParameters `)` `{` GeneratorBody `}`
+ `function` `*` `(` FormalParameters `)` `{` GeneratorBody `}`
+
+ AsyncGeneratorDeclaration :
+ `async` `function` `*` BindingIdentifier `(` FormalParameters `)` `{` AsyncGeneratorBody `}`
+ `async` `function` `*` `(` FormalParameters `)` `{` AsyncGeneratorBody `}`
+
+ AsyncFunctionDeclaration :
+ `async` `function` BindingIdentifier `(` FormalParameters `)` `{` AsyncFunctionBody `}`
+ `async` `function` `(` FormalParameters `)` `{` AsyncFunctionBody `}`
+
+
+ 1. Return *false*.
+
+
+ ClassDeclaration :
+ `class` BindingIdentifier ClassTail
+ `class` ClassTail
+
+
+ 1. Return *false*.
+
+
+
+
+ Static Semantics: IsAwaitUsingDeclaration ( ): a Boolean
+
+
+ LexicalDeclaration : LetOrConst BindingList `;`
+
+ 1. Return *false*.
+
+ UsingDeclaration : `using` BindingList `;`
+
+ 1. Return *false*.
+
+ AwaitUsingDeclaration : CoverAwaitExpressionAndAwaitUsingDeclarationHead BindingList `;`
+
+ 1. Return *true*.
+
+ ForDeclaration : LetOrConst ForBinding
+
+ 1. Return *false*.
+
+ ForDeclaration : `using` ForBinding
+
+ 1. Return *false*.
+
+ ForDeclaration : `await` `using` ForBinding
+
+ 1. Return *true*.
+
+
+ FunctionDeclaration :
+ `function` BindingIdentifier `(` FormalParameters `)` `{` FunctionBody `}`
+ `function` `(` FormalParameters `)` `{` FunctionBody `}`
+
+ GeneratorDeclaration :
+ `function` `*` BindingIdentifier `(` FormalParameters `)` `{` GeneratorBody `}`
+ `function` `*` `(` FormalParameters `)` `{` GeneratorBody `}`
+
+ AsyncGeneratorDeclaration :
+ `async` `function` `*` BindingIdentifier `(` FormalParameters `)` `{` AsyncGeneratorBody `}`
+ `async` `function` `*` `(` FormalParameters `)` `{` AsyncGeneratorBody `}`
+
+ AsyncFunctionDeclaration :
+ `async` `function` BindingIdentifier `(` FormalParameters `)` `{` AsyncFunctionBody `}`
+ `async` `function` `(` FormalParameters `)` `{` AsyncFunctionBody `}`
+
+
+ 1. Return *false*.
+
+
+ ClassDeclaration :
+ `class` BindingIdentifier ClassTail
+ `class` ClassTail
+
+
+ 1. Return *false*.
+
+
+
Static Semantics: LexicallyDeclaredNames ( ): a List of Strings
@@ -7630,9 +8168,9 @@ Static Semantics: LexicallyScopedDeclarations ( ): a List of Parse Nodes
StatementList : StatementList StatementListItem
- 1. Let _declarations1_ be the LexicallyScopedDeclarations of |StatementList|.
- 1. Let _declarations2_ be the LexicallyScopedDeclarations of |StatementListItem|.
- 1. Return the list-concatenation of _declarations1_ and _declarations2_.
+ 1. Let _decls1_ be the LexicallyScopedDeclarations of |StatementList|.
+ 1. Let _decls2_ be the LexicallyScopedDeclarations of |StatementListItem|.
+ 1. Return the list-concatenation of _decls1_ and _decls2_.
StatementListItem : Statement
@@ -7649,18 +8187,18 @@ Static Semantics: LexicallyScopedDeclarations ( ): a List of Parse Nodes
CaseBlock : `{` CaseClauses? DefaultClause CaseClauses? `}`
- 1. If the first |CaseClauses| is present, let _declarations1_ be the LexicallyScopedDeclarations of the first |CaseClauses|.
- 1. Else, let _declarations1_ be a new empty List.
- 1. Let _declarations2_ be the LexicallyScopedDeclarations of |DefaultClause|.
- 1. If the second |CaseClauses| is present, let _declarations3_ be the LexicallyScopedDeclarations of the second |CaseClauses|.
- 1. Else, let _declarations3_ be a new empty List.
- 1. Return the list-concatenation of _declarations1_, _declarations2_, and _declarations3_.
+ 1. If the first |CaseClauses| is present, let _decls1_ be the LexicallyScopedDeclarations of the first |CaseClauses|.
+ 1. Else, let _decls1_ be a new empty List.
+ 1. Let _decls2_ be the LexicallyScopedDeclarations of |DefaultClause|.
+ 1. If the second |CaseClauses| is present, let _decls3_ be the LexicallyScopedDeclarations of the second |CaseClauses|.
+ 1. Else, let _decls3_ be a new empty List.
+ 1. Return the list-concatenation of _decls1_, _decls2_, and _decls3_.
CaseClauses : CaseClauses CaseClause
- 1. Let _declarations1_ be the LexicallyScopedDeclarations of |CaseClauses|.
- 1. Let _declarations2_ be the LexicallyScopedDeclarations of |CaseClause|.
- 1. Return the list-concatenation of _declarations1_ and _declarations2_.
+ 1. Let _decls1_ be the LexicallyScopedDeclarations of |CaseClauses|.
+ 1. Let _decls2_ be the LexicallyScopedDeclarations of |CaseClause|.
+ 1. Return the list-concatenation of _decls1_ and _decls2_.
CaseClause : `case` Expression `:` StatementList?
@@ -7724,9 +8262,9 @@ Static Semantics: LexicallyScopedDeclarations ( ): a List of Parse Nodes
ModuleItemList : ModuleItemList ModuleItem
- 1. Let _declarations1_ be the LexicallyScopedDeclarations of |ModuleItemList|.
- 1. Let _declarations2_ be the LexicallyScopedDeclarations of |ModuleItem|.
- 1. Return the list-concatenation of _declarations1_ and _declarations2_.
+ 1. Let _decls1_ be the LexicallyScopedDeclarations of |ModuleItemList|.
+ 1. Let _decls2_ be the LexicallyScopedDeclarations of |ModuleItem|.
+ 1. Return the list-concatenation of _decls1_ and _decls2_.
ModuleItem : ImportDeclaration
@@ -7734,7 +8272,7 @@ Static Semantics: LexicallyScopedDeclarations ( ): a List of Parse Nodes
ExportDeclaration :
- `export` ExportFromClause FromClause `;`
+ `export` ExportFromClause FromClause WithClause? `;`
`export` NamedExports `;`
`export` VariableStatement
@@ -7994,9 +8532,9 @@ Static Semantics: VarScopedDeclarations ( ): a List of Parse Nodes
StatementList : StatementList StatementListItem
- 1. Let _declarations1_ be the VarScopedDeclarations of |StatementList|.
- 1. Let _declarations2_ be the VarScopedDeclarations of |StatementListItem|.
- 1. Return the list-concatenation of _declarations1_ and _declarations2_.
+ 1. Let _decls1_ be the VarScopedDeclarations of |StatementList|.
+ 1. Let _decls2_ be the VarScopedDeclarations of |StatementListItem|.
+ 1. Return the list-concatenation of _decls1_ and _decls2_.
StatementListItem : Declaration
@@ -8008,14 +8546,14 @@ Static Semantics: VarScopedDeclarations ( ): a List of Parse Nodes
VariableDeclarationList : VariableDeclarationList `,` VariableDeclaration
- 1. Let _declarations1_ be the VarScopedDeclarations of |VariableDeclarationList|.
- 1. Return the list-concatenation of _declarations1_ and « |VariableDeclaration| ».
+ 1. Let _decls1_ be the VarScopedDeclarations of |VariableDeclarationList|.
+ 1. Return the list-concatenation of _decls1_ and « |VariableDeclaration| ».
IfStatement : `if` `(` Expression `)` Statement `else` Statement
- 1. Let _declarations1_ be the VarScopedDeclarations of the first |Statement|.
- 1. Let _declarations2_ be the VarScopedDeclarations of the second |Statement|.
- 1. Return the list-concatenation of _declarations1_ and _declarations2_.
+ 1. Let _decls1_ be the VarScopedDeclarations of the first |Statement|.
+ 1. Let _decls2_ be the VarScopedDeclarations of the second |Statement|.
+ 1. Return the list-concatenation of _decls1_ and _decls2_.
IfStatement : `if` `(` Expression `)` Statement
@@ -8035,9 +8573,9 @@ Static Semantics: VarScopedDeclarations ( ): a List of Parse Nodes
ForStatement : `for` `(` `var` VariableDeclarationList `;` Expression? `;` Expression? `)` Statement
- 1. Let _declarations1_ be the VarScopedDeclarations of |VariableDeclarationList|.
- 1. Let _declarations2_ be the VarScopedDeclarations of |Statement|.
- 1. Return the list-concatenation of _declarations1_ and _declarations2_.
+ 1. Let _decls1_ be the VarScopedDeclarations of |VariableDeclarationList|.
+ 1. Let _decls2_ be the VarScopedDeclarations of |Statement|.
+ 1. Return the list-concatenation of _decls1_ and _decls2_.
ForStatement : `for` `(` LexicalDeclaration Expression? `;` Expression? `)` Statement
@@ -8062,9 +8600,9 @@ Static Semantics: VarScopedDeclarations ( ): a List of Parse Nodes
`for` `await` `(` `var` ForBinding `of` AssignmentExpression `)` Statement
- 1. Let _declarations1_ be « |ForBinding| ».
- 1. Let _declarations2_ be the VarScopedDeclarations of |Statement|.
- 1. Return the list-concatenation of _declarations1_ and _declarations2_.
+ 1. Let _decls1_ be « |ForBinding| ».
+ 1. Let _decls2_ be the VarScopedDeclarations of |Statement|.
+ 1. Return the list-concatenation of _decls1_ and _decls2_.
This section is extended by Annex
@@ -8083,18 +8621,18 @@ Static Semantics: VarScopedDeclarations ( ): a List of Parse Nodes
CaseBlock : `{` CaseClauses? DefaultClause CaseClauses? `}`
- 1. If the first |CaseClauses| is present, let _declarations1_ be the VarScopedDeclarations of the first |CaseClauses|.
- 1. Else, let _declarations1_ be a new empty List.
- 1. Let _declarations2_ be the VarScopedDeclarations of |DefaultClause|.
- 1. If the second |CaseClauses| is present, let _declarations3_ be the VarScopedDeclarations of the second |CaseClauses|.
- 1. Else, let _declarations3_ be a new empty List.
- 1. Return the list-concatenation of _declarations1_, _declarations2_, and _declarations3_.
+ 1. If the first |CaseClauses| is present, let _decls1_ be the VarScopedDeclarations of the first |CaseClauses|.
+ 1. Else, let _decls1_ be a new empty List.
+ 1. Let _decls2_ be the VarScopedDeclarations of |DefaultClause|.
+ 1. If the second |CaseClauses| is present, let _decls3_ be the VarScopedDeclarations of the second |CaseClauses|.
+ 1. Else, let _decls3_ be a new empty List.
+ 1. Return the list-concatenation of _decls1_, _decls2_, and _decls3_.
CaseClauses : CaseClauses CaseClause
- 1. Let _declarations1_ be the VarScopedDeclarations of |CaseClauses|.
- 1. Let _declarations2_ be the VarScopedDeclarations of |CaseClause|.
- 1. Return the list-concatenation of _declarations1_ and _declarations2_.
+ 1. Let _decls1_ be the VarScopedDeclarations of |CaseClauses|.
+ 1. Let _decls2_ be the VarScopedDeclarations of |CaseClause|.
+ 1. Return the list-concatenation of _decls1_ and _decls2_.
CaseClause : `case` Expression `:` StatementList?
@@ -8116,22 +8654,22 @@ Static Semantics: VarScopedDeclarations ( ): a List of Parse Nodes
TryStatement : `try` Block Catch
- 1. Let _declarations1_ be the VarScopedDeclarations of |Block|.
- 1. Let _declarations2_ be the VarScopedDeclarations of |Catch|.
- 1. Return the list-concatenation of _declarations1_ and _declarations2_.
+ 1. Let _decls1_ be the VarScopedDeclarations of |Block|.
+ 1. Let _decls2_ be the VarScopedDeclarations of |Catch|.
+ 1. Return the list-concatenation of _decls1_ and _decls2_.
TryStatement : `try` Block Finally
- 1. Let _declarations1_ be the VarScopedDeclarations of |Block|.
- 1. Let _declarations2_ be the VarScopedDeclarations of |Finally|.
- 1. Return the list-concatenation of _declarations1_ and _declarations2_.
+ 1. Let _decls1_ be the VarScopedDeclarations of |Block|.
+ 1. Let _decls2_ be the VarScopedDeclarations of |Finally|.
+ 1. Return the list-concatenation of _decls1_ and _decls2_.
TryStatement : `try` Block Catch Finally
- 1. Let _declarations1_ be the VarScopedDeclarations of |Block|.
- 1. Let _declarations2_ be the VarScopedDeclarations of |Catch|.
- 1. Let _declarations3_ be the VarScopedDeclarations of |Finally|.
- 1. Return the list-concatenation of _declarations1_, _declarations2_, and _declarations3_.
+ 1. Let _decls1_ be the VarScopedDeclarations of |Block|.
+ 1. Let _decls2_ be the VarScopedDeclarations of |Catch|.
+ 1. Let _decls3_ be the VarScopedDeclarations of |Finally|.
+ 1. Return the list-concatenation of _decls1_, _decls2_, and _decls3_.
Catch : `catch` `(` CatchParameter `)` Block
@@ -8177,9 +8715,9 @@ Static Semantics: VarScopedDeclarations ( ): a List of Parse Nodes
ModuleItemList : ModuleItemList ModuleItem
- 1. Let _declarations1_ be the VarScopedDeclarations of |ModuleItemList|.
- 1. Let _declarations2_ be the VarScopedDeclarations of |ModuleItem|.
- 1. Return the list-concatenation of _declarations1_ and _declarations2_.
+ 1. Let _decls1_ be the VarScopedDeclarations of |ModuleItemList|.
+ 1. Let _decls2_ be the VarScopedDeclarations of |ModuleItem|.
+ 1. Return the list-concatenation of _decls1_ and _decls2_.
ModuleItem : ImportDeclaration
@@ -8223,9 +8761,9 @@ Static Semantics: TopLevelLexicallyScopedDeclarations ( ): a List of Parse N
StatementList : StatementList StatementListItem
- 1. Let _declarations1_ be the TopLevelLexicallyScopedDeclarations of |StatementList|.
- 1. Let _declarations2_ be the TopLevelLexicallyScopedDeclarations of |StatementListItem|.
- 1. Return the list-concatenation of _declarations1_ and _declarations2_.
+ 1. Let _decls1_ be the TopLevelLexicallyScopedDeclarations of |StatementList|.
+ 1. Let _decls2_ be the TopLevelLexicallyScopedDeclarations of |StatementListItem|.
+ 1. Return the list-concatenation of _decls1_ and _decls2_.
StatementListItem : Statement
@@ -8284,9 +8822,9 @@ Static Semantics: TopLevelVarScopedDeclarations ( ): a List of Parse Nodes
StatementList : StatementList StatementListItem
- 1. Let _declarations1_ be the TopLevelVarScopedDeclarations of |StatementList|.
- 1. Let _declarations2_ be the TopLevelVarScopedDeclarations of |StatementListItem|.
- 1. Return the list-concatenation of _declarations1_ and _declarations2_.
+ 1. Let _decls1_ be the TopLevelVarScopedDeclarations of |StatementList|.
+ 1. Let _decls2_ be the TopLevelVarScopedDeclarations of |StatementListItem|.
+ 1. Return the list-concatenation of _decls1_ and _decls2_.
StatementListItem : Statement
@@ -8296,8 +8834,8 @@ Static Semantics: TopLevelVarScopedDeclarations ( ): a List of Parse NodesStatementListItem : Declaration
1. If |Declaration| is Declaration : HoistableDeclaration , then
- 1. Let _declaration_ be the DeclarationPart of |HoistableDeclaration|.
- 1. Return « _declaration_ ».
+ 1. Let _decl_ be the DeclarationPart of |HoistableDeclaration|.
+ 1. Return « _decl_ ».
1. Return a new empty List.
LabelledStatement : LabelIdentifier `:` LabelledItem
@@ -8575,8 +9113,8 @@
BreakStatement : `break` LabelIdentifier `;`
- 1. If _labelSet_ does not contain the StringValue of |LabelIdentifier|, return *true*.
- 1. Return *false*.
+ 1. If _labelSet_ contains the StringValue of |LabelIdentifier|, return *false*.
+ 1. Return *true*.
WithStatement : `with` `(` Expression `)` Statement
@@ -8764,8 +9302,8 @@
ContinueStatement : `continue` LabelIdentifier `;`
- 1. If _iterationSet_ does not contain the StringValue of |LabelIdentifier|, return *true*.
- 1. Return *false*.
+ 1. If _iterationSet_ contains the StringValue of |LabelIdentifier|, return *false*.
+ 1. Return *true*.
WithStatement : `with` `(` Expression `)` Statement
@@ -8969,7 +9507,7 @@ Static Semantics: IsFunctionDefinition ( ): a Boolean
`-` UnaryExpression
`~` UnaryExpression
`!` UnaryExpression
- AwaitExpression
+ CoverAwaitExpressionAndAwaitUsingDeclarationHead
ExponentiationExpression :
UpdateExpression `**` ExponentiationExpression
@@ -9175,9 +9713,8 @@
ClassExpression : `class` ClassTail
- 1. Let _value_ be ? ClassDefinitionEvaluation of |ClassTail| with arguments *undefined* and _name_.
- 1. Set _value_.[[SourceText]] to the source text matched by |ClassExpression|.
- 1. Return _value_.
+ 1. Let _sourceText_ be the source text matched by |ClassExpression|.
+ 1. Return ? ClassDefinitionEvaluation of |ClassTail| with arguments *undefined*, _name_, and _sourceText_.
@@ -9241,7 +9778,8 @@
1. If _symbol_ is |ClassBody|, return *true*.
1. If _symbol_ is |ClassHeritage|, then
- 1. If |ClassHeritage| is present, return *true*; otherwise return *false*.
+ 1. If |ClassHeritage| is present, return *true*.
+ 1. Return *false*.
1. If |ClassHeritage| is present, then
1. If |ClassHeritage| Contains _symbol_ is *true*, return *true*.
1. Return the result of ComputedPropertyContains of |ClassBody| with argument _symbol_.
@@ -9394,7 +9932,7 @@ Miscellaneous
Runtime Semantics: InstantiateFunctionObject (
- _env_: an Environment Record,
+ _envRecord_: an Environment Record,
_privateEnv_: a PrivateEnvironment Record or *null*,
): an ECMAScript function object
@@ -9406,7 +9944,7 @@
`function` `(` FormalParameters `)` `{` FunctionBody `}`
- 1. Return InstantiateOrdinaryFunctionObject of |FunctionDeclaration| with arguments _env_ and _privateEnv_.
+ 1. Return InstantiateOrdinaryFunctionObject of |FunctionDeclaration| with arguments _envRecord_ and _privateEnv_.
GeneratorDeclaration :
@@ -9414,7 +9952,7 @@
`function` `*` `(` FormalParameters `)` `{` GeneratorBody `}`
- 1. Return InstantiateGeneratorFunctionObject of |GeneratorDeclaration| with arguments _env_ and _privateEnv_.
+ 1. Return InstantiateGeneratorFunctionObject of |GeneratorDeclaration| with arguments _envRecord_ and _privateEnv_.
AsyncGeneratorDeclaration :
@@ -9422,7 +9960,7 @@
`async` `function` `*` `(` FormalParameters `)` `{` AsyncGeneratorBody `}`
- 1. Return InstantiateAsyncGeneratorFunctionObject of |AsyncGeneratorDeclaration| with arguments _env_ and _privateEnv_.
+ 1. Return InstantiateAsyncGeneratorFunctionObject of |AsyncGeneratorDeclaration| with arguments _envRecord_ and _privateEnv_.
AsyncFunctionDeclaration :
@@ -9430,7 +9968,7 @@
`async` `function` `(` FormalParameters `)` `{` AsyncFunctionBody `}`
- 1. Return InstantiateAsyncFunctionObject of |AsyncFunctionDeclaration| with arguments _env_ and _privateEnv_.
+ 1. Return InstantiateAsyncFunctionObject of |AsyncFunctionDeclaration| with arguments _envRecord_ and _privateEnv_.
@@ -9438,36 +9976,36 @@
Runtime Semantics: BindingInitialization (
_value_: an ECMAScript language value,
- _environment_: an Environment Record or *undefined*,
+ _envRecord_: an Environment Record or *undefined*,
): either a normal completion containing ~unused~ or an abrupt completion
- *undefined* is passed for _environment_ to indicate that a PutValue operation should be used to assign the initialization value. This is the case for `var` statements and formal parameter lists of some non-strict functions (See
+ *undefined* is passed for _envRecord_ to indicate that a PutValue operation should be used to assign the initialization value. This is the case for `var` statements and formal parameter lists of some non-strict functions (See
BindingIdentifier : Identifier
1. Let _name_ be the StringValue of |Identifier|.
- 1. Return ? InitializeBoundName(_name_, _value_, _environment_).
+ 1. Return ? InitializeBoundName(_name_, _value_, _envRecord_).
BindingIdentifier : `yield`
- 1. Return ? InitializeBoundName(*"yield"*, _value_, _environment_).
+ 1. Return ? InitializeBoundName(*"yield"*, _value_, _envRecord_).
BindingIdentifier : `await`
- 1. Return ? InitializeBoundName(*"await"*, _value_, _environment_).
+ 1. Return ? InitializeBoundName(*"await"*, _value_, _envRecord_).
BindingPattern : ObjectBindingPattern
1. Perform ? RequireObjectCoercible(_value_).
- 1. Return ? BindingInitialization of |ObjectBindingPattern| with arguments _value_ and _environment_.
+ 1. Return ? BindingInitialization of |ObjectBindingPattern| with arguments _value_ and _envRecord_.
BindingPattern : ArrayBindingPattern
1. Let _iteratorRecord_ be ? GetIterator(_value_, ~sync~).
- 1. Let _result_ be Completion(IteratorBindingInitialization of |ArrayBindingPattern| with arguments _iteratorRecord_ and _environment_).
+ 1. Let _result_ be Completion(IteratorBindingInitialization of |ArrayBindingPattern| with arguments _iteratorRecord_ and _envRecord_).
1. If _iteratorRecord_.[[Done]] is *false*, return ? IteratorClose(_iteratorRecord_, _result_).
1. Return ? _result_.
@@ -9481,18 +10019,18 @@
`{` BindingPropertyList `,` `}`
- 1. Perform ? PropertyBindingInitialization of |BindingPropertyList| with arguments _value_ and _environment_.
+ 1. Perform ? PropertyBindingInitialization of |BindingPropertyList| with arguments _value_ and _envRecord_.
1. Return ~unused~.
ObjectBindingPattern : `{` BindingRestProperty `}`
1. Let _excludedNames_ be a new empty List.
- 1. Return ? RestBindingInitialization of |BindingRestProperty| with arguments _value_, _environment_, and _excludedNames_.
+ 1. Return ? RestBindingInitialization of |BindingRestProperty| with arguments _value_, _envRecord_, and _excludedNames_.
ObjectBindingPattern : `{` BindingPropertyList `,` BindingRestProperty `}`
- 1. Let _excludedNames_ be ? PropertyBindingInitialization of |BindingPropertyList| with arguments _value_ and _environment_.
- 1. Return ? RestBindingInitialization of |BindingRestProperty| with arguments _value_, _environment_, and _excludedNames_.
+ 1. Let _excludedNames_ be ? PropertyBindingInitialization of |BindingPropertyList| with arguments _value_ and _envRecord_.
+ 1. Return ? RestBindingInitialization of |BindingRestProperty| with arguments _value_, _envRecord_, and _excludedNames_.
@@ -9500,18 +10038,17 @@
InitializeBoundName (
_name_: a String,
_value_: an ECMAScript language value,
- _environment_: an Environment Record or *undefined*,
+ _envRecord_: an Environment Record or *undefined*,
): either a normal completion containing ~unused~ or an abrupt completion
- 1. If _environment_ is not *undefined*, then
- 1. Perform ! _environment_.InitializeBinding(_name_, _value_).
+ 1. If _envRecord_ is not *undefined*, then
+ 1. Perform ! _envRecord_.InitializeBinding(_name_, _value_).
1. Return ~unused~.
- 1. Else,
- 1. Let _lhs_ be ? ResolveBinding(_name_).
- 1. Return ? PutValue(_lhs_, _value_).
+ 1. Let _lhs_ be ? ResolveBinding(_name_).
+ 1. Return ? PutValue(_lhs_, _value_).
@@ -9520,13 +10057,13 @@
Runtime Semantics: IteratorBindingInitialization (
_iteratorRecord_: an Iterator Record,
- _environment_: an Environment Record or *undefined*,
+ _envRecord_: an Environment Record or *undefined*,
): either a normal completion containing ~unused~ or an abrupt completion
- When *undefined* is passed for _environment_ it indicates that a PutValue operation should be used to assign the initialization value. This is the case for formal parameter lists of non-strict functions. In that case the formal parameter bindings are preinitialized in order to deal with the possibility of multiple parameters with the same name.
+ When *undefined* is passed for _envRecord_ it indicates that a PutValue operation should be used to assign the initialization value. This is the case for formal parameter lists of non-strict functions. In that case the formal parameter bindings are preinitialized in order to deal with the possibility of multiple parameters with the same name.
ArrayBindingPattern : `[` `]`
@@ -9540,34 +10077,34 @@
1. If |Elision| is present, then
1. Perform ? IteratorDestructuringAssignmentEvaluation of |Elision| with argument _iteratorRecord_.
- 1. Return ? IteratorBindingInitialization of |BindingRestElement| with arguments _iteratorRecord_ and _environment_.
+ 1. Return ? IteratorBindingInitialization of |BindingRestElement| with arguments _iteratorRecord_ and _envRecord_.
ArrayBindingPattern : `[` BindingElementList `,` Elision `]`
- 1. Perform ? IteratorBindingInitialization of |BindingElementList| with arguments _iteratorRecord_ and _environment_.
+ 1. Perform ? IteratorBindingInitialization of |BindingElementList| with arguments _iteratorRecord_ and _envRecord_.
1. Return ? IteratorDestructuringAssignmentEvaluation of |Elision| with argument _iteratorRecord_.
ArrayBindingPattern : `[` BindingElementList `,` Elision? BindingRestElement `]`
- 1. Perform ? IteratorBindingInitialization of |BindingElementList| with arguments _iteratorRecord_ and _environment_.
+ 1. Perform ? IteratorBindingInitialization of |BindingElementList| with arguments _iteratorRecord_ and _envRecord_.
1. If |Elision| is present, then
1. Perform ? IteratorDestructuringAssignmentEvaluation of |Elision| with argument _iteratorRecord_.
- 1. Return ? IteratorBindingInitialization of |BindingRestElement| with arguments _iteratorRecord_ and _environment_.
+ 1. Return ? IteratorBindingInitialization of |BindingRestElement| with arguments _iteratorRecord_ and _envRecord_.
BindingElementList : BindingElementList `,` BindingElisionElement
- 1. Perform ? IteratorBindingInitialization of |BindingElementList| with arguments _iteratorRecord_ and _environment_.
- 1. Return ? IteratorBindingInitialization of |BindingElisionElement| with arguments _iteratorRecord_ and _environment_.
+ 1. Perform ? IteratorBindingInitialization of |BindingElementList| with arguments _iteratorRecord_ and _envRecord_.
+ 1. Return ? IteratorBindingInitialization of |BindingElisionElement| with arguments _iteratorRecord_ and _envRecord_.
BindingElisionElement : Elision BindingElement
1. Perform ? IteratorDestructuringAssignmentEvaluation of |Elision| with argument _iteratorRecord_.
- 1. Return ? IteratorBindingInitialization of |BindingElement| with arguments _iteratorRecord_ and _environment_.
+ 1. Return ? IteratorBindingInitialization of |BindingElement| with arguments _iteratorRecord_ and _envRecord_.
SingleNameBinding : BindingIdentifier Initializer?
1. Let _bindingId_ be the StringValue of |BindingIdentifier|.
- 1. Let _lhs_ be ? ResolveBinding(_bindingId_, _environment_).
+ 1. Let _lhs_ be ? ResolveBinding(_bindingId_, _envRecord_).
1. Let _v_ be *undefined*.
1. If _iteratorRecord_.[[Done]] is *false*, then
1. Let _next_ be ? IteratorStepValue(_iteratorRecord_).
@@ -9579,7 +10116,7 @@
1. Else,
1. Let _defaultValue_ be ? Evaluation of |Initializer|.
1. Set _v_ to ? GetValue(_defaultValue_).
- 1. If _environment_ is *undefined*, return ? PutValue(_lhs_, _v_).
+ 1. If _envRecord_ is *undefined*, return ? PutValue(_lhs_, _v_).
1. Return ? InitializeReferencedBinding(_lhs_, _v_).
BindingElement : BindingPattern Initializer?
@@ -9592,34 +10129,34 @@
1. If |Initializer| is present and _v_ is *undefined*, then
1. Let _defaultValue_ be ? Evaluation of |Initializer|.
1. Set _v_ to ? GetValue(_defaultValue_).
- 1. Return ? BindingInitialization of |BindingPattern| with arguments _v_ and _environment_.
+ 1. Return ? BindingInitialization of |BindingPattern| with arguments _v_ and _envRecord_.
BindingRestElement : `...` BindingIdentifier
- 1. Let _lhs_ be ? ResolveBinding(StringValue of |BindingIdentifier|, _environment_).
- 1. Let _A_ be ! ArrayCreate(0).
+ 1. Let _lhs_ be ? ResolveBinding(StringValue of |BindingIdentifier|, _envRecord_).
+ 1. Let _array_ be ! ArrayCreate(0).
1. Let _n_ be 0.
1. Repeat,
1. Let _next_ be ~done~.
1. If _iteratorRecord_.[[Done]] is *false*, then
1. Set _next_ to ? IteratorStepValue(_iteratorRecord_).
1. If _next_ is ~done~, then
- 1. If _environment_ is *undefined*, return ? PutValue(_lhs_, _A_).
- 1. Return ? InitializeReferencedBinding(_lhs_, _A_).
- 1. Perform ! CreateDataPropertyOrThrow(_A_, ! ToString(𝔽(_n_)), _next_).
+ 1. If _envRecord_ is *undefined*, return ? PutValue(_lhs_, _array_).
+ 1. Return ? InitializeReferencedBinding(_lhs_, _array_).
+ 1. Perform ! CreateDataPropertyOrThrow(_array_, ! ToString(𝔽(_n_)), _next_).
1. Set _n_ to _n_ + 1.
BindingRestElement : `...` BindingPattern
- 1. Let _A_ be ! ArrayCreate(0).
+ 1. Let _array_ be ! ArrayCreate(0).
1. Let _n_ be 0.
1. Repeat,
1. Let _next_ be ~done~.
1. If _iteratorRecord_.[[Done]] is *false*, then
1. Set _next_ to ? IteratorStepValue(_iteratorRecord_).
1. If _next_ is ~done~, then
- 1. Return ? BindingInitialization of |BindingPattern| with arguments _A_ and _environment_.
- 1. Perform ! CreateDataPropertyOrThrow(_A_, ! ToString(𝔽(_n_)), _next_).
+ 1. Return ? BindingInitialization of |BindingPattern| with arguments _array_ and _envRecord_.
+ 1. Perform ! CreateDataPropertyOrThrow(_array_, ! ToString(𝔽(_n_)), _next_).
1. Set _n_ to _n_ + 1.
FormalParameters : [empty]
@@ -9628,13 +10165,13 @@
FormalParameters : FormalParameterList `,` FunctionRestParameter
- 1. Perform ? IteratorBindingInitialization of |FormalParameterList| with arguments _iteratorRecord_ and _environment_.
- 1. Return ? IteratorBindingInitialization of |FunctionRestParameter| with arguments _iteratorRecord_ and _environment_.
+ 1. Perform ? IteratorBindingInitialization of |FormalParameterList| with arguments _iteratorRecord_ and _envRecord_.
+ 1. Return ? IteratorBindingInitialization of |FunctionRestParameter| with arguments _iteratorRecord_ and _envRecord_.
FormalParameterList : FormalParameterList `,` FormalParameter
- 1. Perform ? IteratorBindingInitialization of |FormalParameterList| with arguments _iteratorRecord_ and _environment_.
- 1. Return ? IteratorBindingInitialization of |FormalParameter| with arguments _iteratorRecord_ and _environment_.
+ 1. Perform ? IteratorBindingInitialization of |FormalParameterList| with arguments _iteratorRecord_ and _envRecord_.
+ 1. Return ? IteratorBindingInitialization of |FormalParameter| with arguments _iteratorRecord_ and _envRecord_.
ArrowParameters : BindingIdentifier
@@ -9643,12 +10180,12 @@
1. Let _next_ be ? IteratorStepValue(_iteratorRecord_).
1. If _next_ is not ~done~, then
1. Set _v_ to _next_.
- 1. Return ? BindingInitialization of |BindingIdentifier| with arguments _v_ and _environment_.
+ 1. Return ? BindingInitialization of |BindingIdentifier| with arguments _v_ and _envRecord_.
ArrowParameters : CoverParenthesizedExpressionAndArrowParameterList
1. Let _formals_ be the |ArrowFormalParameters| that is covered by |CoverParenthesizedExpressionAndArrowParameterList|.
- 1. Return ? IteratorBindingInitialization of _formals_ with arguments _iteratorRecord_ and _environment_.
+ 1. Return ? IteratorBindingInitialization of _formals_ with arguments _iteratorRecord_ and _envRecord_.
AsyncArrowBindingIdentifier : BindingIdentifier
@@ -9659,12 +10196,12 @@
1. Let _next_ be ? IteratorStepValue(_iteratorRecord_).
1. If _next_ is not ~done~, then
1. Set _v_ to _next_.
- 1. Return ? BindingInitialization of |BindingIdentifier| with arguments _v_ and _environment_.
+ 1. Return ? BindingInitialization of |BindingIdentifier| with arguments _v_ and _envRecord_.
- Static Semantics: AssignmentTargetType ( ): ~simple~ or ~invalid~
+ Static Semantics: AssignmentTargetType ( ): ~simple~, ~web-compat~, or ~invalid~
IdentifierReference : Identifier
@@ -9699,6 +10236,16 @@ Static Semantics: AssignmentTargetType ( ): ~simple~ or ~invalid~
1. Let _expr_ be the |ParenthesizedExpression| that is covered by |CoverParenthesizedExpressionAndArrowParameterList|.
1. Return the AssignmentTargetType of _expr_.
+
+ CallExpression :
+ CoverCallExpressionAndAsyncArrowHead
+ CallExpression Arguments
+
+
+ 1. [id="step-assignmenttargettype-web-compat", normative-optional] If the host is a web browser or otherwise supports
PrimaryExpression :
`this`
@@ -9714,10 +10261,8 @@ Static Semantics: AssignmentTargetType ( ): ~simple~ or ~invalid~
TemplateLiteral
CallExpression :
- CoverCallExpressionAndAsyncArrowHead
SuperCall
ImportCall
- CallExpression Arguments
CallExpression TemplateLiteral
NewExpression :
@@ -9750,7 +10295,7 @@ Static Semantics: AssignmentTargetType ( ): ~simple~ or ~invalid~
`-` UnaryExpression
`~` UnaryExpression
`!` UnaryExpression
- AwaitExpression
+ CoverAwaitExpressionAndAwaitUsingDeclarationHead
ExponentiationExpression :
UpdateExpression `**` ExponentiationExpression
@@ -9837,18 +10382,26 @@ Static Semantics: PropName ( ): a String or ~empty~
1. Return the PropName of |PropertyName|.
- LiteralPropertyName : IdentifierName
+
+ LiteralPropertyName : IdentifierName
+
+ AttributeKey : IdentifierName
+
1. Return the StringValue of |IdentifierName|.
- LiteralPropertyName : StringLiteral
+
+ LiteralPropertyName : StringLiteral
+
+ AttributeKey : StringLiteral
+
1. Return the SV of |StringLiteral|.
LiteralPropertyName : NumericLiteral
- 1. Let _nbr_ be the NumericValue of |NumericLiteral|.
- 1. Return ! ToString(_nbr_).
+ 1. Let _number_ be the NumericValue of |NumericLiteral|.
+ 1. Return ! ToString(_number_).
ComputedPropertyName : `[` AssignmentExpression `]`
@@ -9898,6 +10451,28 @@ Static Semantics: PropName ( ): a String or ~empty~
1. Return ~empty~.
+
+
+ Static Semantics: ContainsUsing ( ): a Boolean
+
+
+ StatementList : StatementList StatementListItem
+
+ 1. If ContainsUsing of the derived |StatementList| is *true*, return *true*.
+ 1. If ContainsUsing of |StatementListItem| is *true*, return *true*.
+ 1. Return *false*.
+
+ StatementListItem : Statement
+
+ 1. Return *false*.
+
+ StatementListItem : Declaration
+
+ 1. If IsUsingDeclaration of |Declaration| is *true*, return *true*.
+ 1. If IsAwaitUsingDeclaration of |Declaration| is *true*, return *true*.
+ 1. Return *false*.
+
+
@@ -9907,7 +10482,7 @@ Executable Code and Execution Contexts
Environment Records
Environment Record is a specification type used to define the association of |Identifier|s to specific variables and functions, based upon the lexical nesting structure of ECMAScript code. Usually an Environment Record is associated with some specific syntactic structure of ECMAScript code such as a |FunctionDeclaration|, a |BlockStatement|, or a |Catch| clause of a |TryStatement|. Each time such code is evaluated, a new Environment Record is created to record the identifier bindings that are created by that code.
- Every Environment Record has an [[OuterEnv]] field, which is either *null* or a reference to an outer Environment Record. This is used to model the logical nesting of Environment Record values. The outer reference of an (inner) Environment Record is a reference to the Environment Record that logically surrounds the inner Environment Record. An outer Environment Record may, of course, have its own outer Environment Record. An Environment Record may serve as the outer environment for multiple inner Environment Records. For example, if a |FunctionDeclaration| contains two nested |FunctionDeclaration|s then the Environment Records of each of the nested functions will have as their outer Environment Record the Environment Record of the current evaluation of the surrounding function.
+ Every Environment Record has an [[OuterEnv]] field, which is either *null* or a reference to an outer Environment Record. This is used to model the logical nesting of Environment Records. The outer reference of an (inner) Environment Record is a reference to the Environment Record that logically surrounds the inner Environment Record. An outer Environment Record may, of course, have its own outer Environment Record. An Environment Record may serve as the outer environment for multiple inner Environment Records. For example, if a |FunctionDeclaration| contains two nested |FunctionDeclaration|s then the Environment Records of each of the nested functions will have as their outer Environment Record the Environment Record of the current evaluation of the surrounding function.
Environment Records are purely specification mechanisms and need not correspond to any specific artefact of an ECMAScript implementation. It is impossible for an ECMAScript program to directly access or manipulate such values.
@@ -9939,94 +10514,163 @@ The Environment Record Type Hierarchy
The Environment Record abstract class includes the abstract specification methods defined in
-
+
-
-
- Method
-
-
- Purpose
-
+
+
+
+ Method
+
+
+ Purpose
+
+
+ Definitions
+
+
+
+
+
+ HasBinding (
+ _name_: a String,
+ ): either a normal completion containing a Boolean or a throw completion
+
+
+ It determines if an Environment Record has a binding for _name_.
+
+
+ It has concrete definitions in the following types:
+
-
+
+
+ CreateMutableBinding (
+ _name_: a String,
+ _deletable_: a Boolean,
+ ): either a normal completion containing ~unused~ or a throw completion
+
- HasBinding(N)
+ It creates a new but uninitialized mutable binding in an Environment Record. _name_ is the text of the bound name. If _deletable_ is *true* the binding may be subsequently deleted.
- Determine if an Environment Record has a binding for the String value _N_. Return *true* if it does and *false* if it does not.
+ It has concrete definitions in the following types:
+
-
+
- CreateMutableBinding(N, D)
+ CreateImmutableBinding (
+ _name_: a String,
+ _strict_: a Boolean,
+ ): either a normal completion containing ~unused~ or a throw completion
- Create a new but uninitialized mutable binding in an Environment Record. The String value _N_ is the text of the bound name. If the Boolean argument _D_ is *true* the binding may be subsequently deleted.
+ It creates a new but uninitialized immutable binding in an Environment Record. _name_ is the text of the bound name. If _strict_ is *true* then attempts to set it after it has been initialized will always throw an exception, regardless of the strict mode setting of operations that reference that binding.
+
+
+ It has concrete definitions in the following types:
+
-
+
- CreateImmutableBinding(N, S)
+ InitializeBinding (
+ _name_: a String,
+ _value_: an ECMAScript language value,
+ ): either a normal completion containing ~unused~ or a throw completion
- Create a new but uninitialized immutable binding in an Environment Record. The String value _N_ is the text of the bound name. If _S_ is *true* then attempts to set it after it has been initialized will always throw an exception, regardless of the strict mode setting of operations that reference that binding.
+ It sets the value of an already existing but uninitialized binding in an Environment Record. _name_ is the text of the bound name. _value_ is the value for the binding.
+
+
+ It has concrete definitions in the following types:
+
-
+
+
+ SetMutableBinding (
+ _name_: a String,
+ _value_: an ECMAScript language value,
+ _strict_: a Boolean,
+ ): either a normal completion containing ~unused~ or a throw completion
+
- InitializeBinding(N, V)
+ It sets the value of an already existing mutable binding in an Environment Record. _name_ is the text of the bound name. _value_ is the value for the binding. If _strict_ is *true* and the binding cannot be set, this will throw a *TypeError* exception.
- Set the value of an already existing but uninitialized binding in an Environment Record. The String value _N_ is the text of the bound name. _V_ is the value for the binding and is a value of any ECMAScript language type.
+ It has concrete definitions in the following types:
+
-
+
+
+ GetBindingValue (
+ _name_: a String,
+ _strict_: a Boolean,
+ ): either a normal completion containing an ECMAScript language value or a throw completion
+
- SetMutableBinding(N, V, S)
+ It returns the value of an already existing binding from an Environment Record. _name_ is the text of the bound name. _strict_ is used to identify references originating in strict mode code or that otherwise require strict mode reference semantics. If _strict_ is *true* and the binding does not exist, this will throw a *ReferenceError* exception. If the binding exists but is uninitialized a *ReferenceError* is thrown, regardless of the value of _strict_.
- Set the value of an already existing mutable binding in an Environment Record. The String value _N_ is the text of the bound name. _V_ is the value for the binding and may be a value of any ECMAScript language type. _S_ is a Boolean flag. If _S_ is *true* and the binding cannot be set throw a *TypeError* exception.
+ It has concrete definitions in the following types:
+
-
+
- GetBindingValue(N, S)
+ DeleteBinding (
+ _name_: a String,
+ ): either a normal completion containing a Boolean or a throw completion
- Returns the value of an already existing binding from an Environment Record. The String value _N_ is the text of the bound name. _S_ is used to identify references originating in strict mode code or that otherwise require strict mode reference semantics. If _S_ is *true* and the binding does not exist throw a *ReferenceError* exception. If the binding exists but is uninitialized a *ReferenceError* is thrown, regardless of the value of _S_.
+ It deletes a binding from an Environment Record. _name_ is the text of the bound name. If a binding for _name_ exists, this removes the binding and returns *true*. If the binding exists but cannot be removed, this returns *false*. If the binding does not exist, this returns *true*.
+
+
+ It has concrete definitions in the following types:
+
-
+
+ HasThisBinding ( ): a Boolean
- DeleteBinding(N)
+ It determines if an Environment Record establishes a `this` binding. This returns *true* if it does and *false* if it does not.
- Delete a binding from an Environment Record. The String value _N_ is the text of the bound name. If a binding for _N_ exists, remove the binding and return *true*. If the binding exists but cannot be removed return *false*. If the binding does not exist return *true*.
+ It has concrete definitions in the following types:
+
-
+
+ GetThisBinding ( ): either a normal completion containing an ECMAScript language value or a throw completion
- HasThisBinding()
+ It returns the value of this Environment Record's `this` binding. It throws a *ReferenceError* if the `this` binding has not been initialized.
- Determine if an Environment Record establishes a `this` binding. Return *true* if it does and *false* if it does not.
+ It has concrete definitions in the following types:
+
-
+
+ HasSuperBinding ( ): a Boolean
- HasSuperBinding()
+ It determines if an Environment Record establishes a `super` method binding. This returns *true* if it does and *false* if it does not. If it returns *true* it implies that the Environment Record is a Function Environment Record, although the reverse implication does not hold.
- Determine if an Environment Record establishes a `super` method binding. Return *true* if it does and *false* if it does not.
+ It has concrete definitions in the following types:
+
-
+
+ WithBaseObject ( ): an Object or *undefined*
- WithBaseObject()
+ If this Environment Record is associated with a `with` statement, it returns the with object. Otherwise, it returns *undefined*.
- If this Environment Record is associated with a `with` statement, return the with object. Otherwise, return *undefined*.
+ It has concrete definitions in the following types:
+
@@ -10035,23 +10679,23 @@ The Environment Record Type Hierarchy
Declarative Environment Records
Each Declarative Environment Record is associated with an ECMAScript program scope containing variable, constant, let, class, module, import, and/or function declarations. A Declarative Environment Record binds the set of identifiers defined by the declarations contained within its scope.
- The behaviour of the concrete specification methods for Declarative Environment Records is defined by the following algorithms.
+ Every Declarative Environment Record also has a [[DisposableResourceStack]] field, which contains a List of DisposableResource Records. The elements of this list are tracked by the `using` declarations and `await using` declarations that must be disposed when the Evaluation step that constructed the Environment Record has completed.
HasBinding (
- _N_: a String,
+ _name_: a String,
): a normal completion containing a Boolean
- for
- - a Declarative Environment Record _envRec_
+ - a Declarative Environment Record _envRecord_
- description
- It determines if the argument identifier is one of the identifiers bound by the record.
- 1. If _envRec_ has a binding for _N_, return *true*.
+ 1. If _envRecord_ has a binding for _name_, return *true*.
1. Return *false*.
@@ -10059,20 +10703,20 @@
CreateMutableBinding (
- _N_: a String,
- _D_: a Boolean,
+ _name_: a String,
+ _deletable_: a Boolean,
): a normal completion containing ~unused~
- for
- - a Declarative Environment Record _envRec_
+ - a Declarative Environment Record _envRecord_
- description
- - It creates a new mutable binding for the name _N_ that is uninitialized. A binding must not already exist in this Environment Record for _N_. If _D_ is *true*, the new binding is marked as being subject to deletion.
+ - It creates a new mutable binding for the name _name_ that is uninitialized. A binding must not already exist in this Environment Record for _name_. If _deletable_ is *true*, the new binding is marked as being subject to deletion.
- 1. Assert: _envRec_ does not already have a binding for _N_.
- 1. Create a mutable binding in _envRec_ for _N_ and record that it is uninitialized. If _D_ is *true*, record that the newly created binding may be deleted by a subsequent DeleteBinding call.
+ 1. Assert: _envRecord_ does not already have a binding for _name_.
+ 1. Create a mutable binding in _envRecord_ for _name_ and record that it is uninitialized. If _deletable_ is *true*, record that the newly created binding may be deleted by a subsequent DeleteBinding call.
1. Return ~unused~.
@@ -10080,20 +10724,20 @@
CreateImmutableBinding (
- _N_: a String,
- _S_: a Boolean,
+ _name_: a String,
+ _strict_: a Boolean,
): a normal completion containing ~unused~
- for
- - a Declarative Environment Record _envRec_
+ - a Declarative Environment Record _envRecord_
- description
- - It creates a new immutable binding for the name _N_ that is uninitialized. A binding must not already exist in this Environment Record for _N_. If _S_ is *true*, the new binding is marked as a strict binding.
+ - It creates a new immutable binding for the name _name_ that is uninitialized. A binding must not already exist in this Environment Record for _name_. If _strict_ is *true*, the new binding is marked as a strict binding.
- 1. Assert: _envRec_ does not already have a binding for _N_.
- 1. Create an immutable binding in _envRec_ for _N_ and record that it is uninitialized. If _S_ is *true*, record that the newly created binding is a strict binding.
+ 1. Assert: _envRecord_ does not already have a binding for _name_.
+ 1. Create an immutable binding in _envRecord_ for _name_ and record that it is uninitialized. If _strict_ is *true*, record that the newly created binding is a strict binding.
1. Return ~unused~.
@@ -10101,21 +10745,21 @@
InitializeBinding (
- _N_: a String,
- _V_: an ECMAScript language value,
+ _name_: a String,
+ _value_: an ECMAScript language value,
): a normal completion containing ~unused~
- for
- - a Declarative Environment Record _envRec_
+ - a Declarative Environment Record _envRecord_
- description
- - It is used to set the bound value of the current binding of the identifier whose name is _N_ to the value _V_. An uninitialized binding for _N_ must already exist.
+ - It is used to set the bound value of the current binding of the identifier whose name is _name_ to the value _value_. An uninitialized binding for _name_ must already exist.
- 1. Assert: _envRec_ must have an uninitialized binding for _N_.
- 1. Set the bound value for _N_ in _envRec_ to _V_.
- 1. Record that the binding for _N_ in _envRec_ has been initialized.
+ 1. Assert: _envRecord_ must have an uninitialized binding for _name_.
+ 1. Set the bound value for _name_ in _envRecord_ to _value_.
+ 1. Record that the binding for _name_ in _envRecord_ has been initialized.
1. Return ~unused~.
@@ -10123,32 +10767,32 @@
SetMutableBinding (
- _N_: a String,
- _V_: an ECMAScript language value,
- _S_: a Boolean,
+ _name_: a String,
+ _value_: an ECMAScript language value,
+ _strict_: a Boolean,
): either a normal completion containing ~unused~ or a throw completion
- for
- - a Declarative Environment Record _envRec_
+ - a Declarative Environment Record _envRecord_
- description
- - It attempts to change the bound value of the current binding of the identifier whose name is _N_ to the value _V_. A binding for _N_ normally already exists, but in rare cases it may not. If the binding is an immutable binding, a *TypeError* is thrown if _S_ is *true*.
+ - It attempts to change the bound value of the current binding of the identifier whose name is _name_ to the value _value_. A binding for _name_ normally already exists, but in rare cases it may not. If the binding is an immutable binding, a *TypeError* is thrown if _strict_ is *true*.
- 1. [id="step-setmutablebinding-missing-binding"] If _envRec_ does not have a binding for _N_, then
- 1. If _S_ is *true*, throw a *ReferenceError* exception.
- 1. Perform ! _envRec_.CreateMutableBinding(_N_, *true*).
- 1. Perform ! _envRec_.InitializeBinding(_N_, _V_).
+ 1. [id="step-setmutablebinding-missing-binding"] If _envRecord_ does not have a binding for _name_, then
+ 1. If _strict_ is *true*, throw a *ReferenceError* exception.
+ 1. Perform ! _envRecord_.CreateMutableBinding(_name_, *true*).
+ 1. Perform ! _envRecord_.InitializeBinding(_name_, _value_).
1. Return ~unused~.
- 1. If the binding for _N_ in _envRec_ is a strict binding, set _S_ to *true*.
- 1. If the binding for _N_ in _envRec_ has not yet been initialized, then
+ 1. If the binding for _name_ in _envRecord_ is a strict binding, set _strict_ to *true*.
+ 1. If the binding for _name_ in _envRecord_ has not yet been initialized, then
1. Throw a *ReferenceError* exception.
- 1. Else if the binding for _N_ in _envRec_ is a mutable binding, then
- 1. Change its bound value to _V_.
+ 1. Else if the binding for _name_ in _envRecord_ is a mutable binding, then
+ 1. Change its bound value to _value_.
1. Else,
1. Assert: This is an attempt to change the value of an immutable binding.
- 1. If _S_ is *true*, throw a *TypeError* exception.
+ 1. If _strict_ is *true*, throw a *TypeError* exception.
1. Return ~unused~.
@@ -10160,41 +10804,41 @@
GetBindingValue (
- _N_: a String,
- _S_: a Boolean,
+ _name_: a String,
+ _strict_: a Boolean,
): either a normal completion containing an ECMAScript language value or a throw completion
- for
- - a Declarative Environment Record _envRec_
+ - a Declarative Environment Record _envRecord_
- description
- - It returns the value of its bound identifier whose name is _N_. If the binding exists but is uninitialized a *ReferenceError* is thrown, regardless of the value of _S_.
+ - It returns the value of its bound identifier whose name is _name_. If the binding exists but is uninitialized a *ReferenceError* is thrown, regardless of the value of _strict_.
- 1. Assert: _envRec_ has a binding for _N_.
- 1. If the binding for _N_ in _envRec_ is an uninitialized binding, throw a *ReferenceError* exception.
- 1. Return the value currently bound to _N_ in _envRec_.
+ 1. Assert: _envRecord_ has a binding for _name_.
+ 1. If the binding for _name_ in _envRecord_ is an uninitialized binding, throw a *ReferenceError* exception.
+ 1. Return the value currently bound to _name_ in _envRecord_.
DeleteBinding (
- _N_: a String,
+ _name_: a String,
): a normal completion containing a Boolean
- for
- - a Declarative Environment Record _envRec_
+ - a Declarative Environment Record _envRecord_
- description
- It can only delete bindings that have been explicitly designated as being subject to deletion.
- 1. Assert: _envRec_ has a binding for _N_.
- 1. If the binding for _N_ in _envRec_ cannot be deleted, return *false*.
- 1. Remove the binding for _N_ from _envRec_.
+ 1. Assert: _envRecord_ has a binding for _name_.
+ 1. If the binding for _name_ in _envRecord_ cannot be deleted, return *false*.
+ 1. Remove the binding for _name_ from _envRecord_.
1. Return *true*.
@@ -10203,7 +10847,7 @@
HasThisBinding ( ): *false*
- for
- - a Declarative Environment Record _envRec_
+ - a Declarative Environment Record _envRecord_
1. Return *false*.
@@ -10213,11 +10857,16 @@ HasThisBinding ( ): *false*
+
+ GetThisBinding ( )
+ The GetThisBinding concrete method of a Declarative Environment Record is never used within this specification.
+
+
HasSuperBinding ( ): *false*
- for
- - a Declarative Environment Record _envRec_
+ - a Declarative Environment Record _envRecord_
1. Return *false*.
@@ -10231,7 +10880,7 @@ HasSuperBinding ( ): *false*
WithBaseObject ( ): *undefined*
- for
- - a Declarative Environment Record _envRec_
+ - a Declarative Environment Record _envRecord_
1. Return *undefined*.
@@ -10246,17 +10895,19 @@ Object Environment Records
Object Environment Records have the additional state fields listed in
-
-
- Field Name
-
-
- Value
-
-
- Meaning
-
-
+
+
+
+ Field Name
+
+
+ Value
+
+
+ Meaning
+
+
+
[[BindingObject]]
@@ -10281,29 +10932,28 @@ Object Environment Records
- The behaviour of the concrete specification methods for Object Environment Records is defined by the following algorithms.
HasBinding (
- _N_: a String,
+ _name_: a String,
): either a normal completion containing a Boolean or a throw completion
- for
- - an Object Environment Record _envRec_
+ - an Object Environment Record _envRecord_
- description
- - It determines if its associated binding object has a property whose name is _N_.
+ - It determines if its associated binding object has a property whose name is _name_.
- 1. Let _bindingObject_ be _envRec_.[[BindingObject]].
- 1. Let _foundBinding_ be ? HasProperty(_bindingObject_, _N_).
+ 1. Let _bindingObj_ be _envRecord_.[[BindingObject]].
+ 1. Let _foundBinding_ be ? HasProperty(_bindingObj_, _name_).
1. If _foundBinding_ is *false*, return *false*.
- 1. If _envRec_.[[IsWithEnvironment]] is *false*, return *true*.
- 1. Let _unscopables_ be ? Get(_bindingObject_, @@unscopables).
+ 1. If _envRecord_.[[IsWithEnvironment]] is *false*, return *true*.
+ 1. Let _unscopables_ be ? Get(_bindingObj_, %Symbol.unscopables%).
1. If _unscopables_ is an Object, then
- 1. Let _blocked_ be ToBoolean(? Get(_unscopables_, _N_)).
+ 1. Let _blocked_ be ToBoolean(? Get(_unscopables_, _name_)).
1. If _blocked_ is *true*, return *false*.
1. Return *true*.
@@ -10312,48 +10962,48 @@
CreateMutableBinding (
- _N_: a String,
- _D_: a Boolean,
+ _name_: a String,
+ _deletable_: a Boolean,
): either a normal completion containing ~unused~ or a throw completion
- for
- - an Object Environment Record _envRec_
+ - an Object Environment Record _envRecord_
- description
- - It creates in an Environment Record's associated binding object a property whose name is _N_ and initializes it to the value *undefined*. If _D_ is *true*, the new property's [[Configurable]] attribute is set to *true*; otherwise it is set to *false*.
+ - It creates in an Environment Record's associated binding object a property whose name is _name_ and initializes it to the value *undefined*. If _deletable_ is *true*, the new property's [[Configurable]] attribute is set to *true*; otherwise it is set to *false*.
- 1. Let _bindingObject_ be _envRec_.[[BindingObject]].
- 1. Perform ? DefinePropertyOrThrow(_bindingObject_, _N_, PropertyDescriptor { [[Value]]: *undefined*, [[Writable]]: *true*, [[Enumerable]]: *true*, [[Configurable]]: _D_ }).
+ 1. Let _bindingObj_ be _envRecord_.[[BindingObject]].
+ 1. Perform ? DefinePropertyOrThrow(_bindingObj_, _name_, PropertyDescriptor { [[Value]]: *undefined*, [[Writable]]: *true*, [[Enumerable]]: *true*, [[Configurable]]: _deletable_ }).
1. Return ~unused~.
- Normally _envRec_ will not have a binding for _N_ but if it does, the semantics of DefinePropertyOrThrow may result in an existing binding being replaced or shadowed or cause an abrupt completion to be returned.
+ Normally _envRecord_ will not have a binding for _name_ but if it does, the semantics of DefinePropertyOrThrow may result in an existing binding being replaced or shadowed or cause an abrupt completion to be returned.
- CreateImmutableBinding ( _N_, _S_ )
+ CreateImmutableBinding ( _name_, _strict_ )
The CreateImmutableBinding concrete method of an Object Environment Record is never used within this specification.
InitializeBinding (
- _N_: a String,
- _V_: an ECMAScript language value,
+ _name_: a String,
+ _value_: an ECMAScript language value,
): either a normal completion containing ~unused~ or a throw completion
- for
- - an Object Environment Record _envRec_
+ - an Object Environment Record _envRecord_
- description
- - It is used to set the bound value of the current binding of the identifier whose name is _N_ to the value _V_.
+ - It is used to set the bound value of the current binding of the identifier whose name is _name_ to the value _value_.
- 1. Perform ? _envRec_.SetMutableBinding (_N_, _V_, *false*).
+ 1. Perform ? _envRecord_.SetMutableBinding(_name_, _value_, *false*) .
1. Return ~unused~.
@@ -10364,23 +11014,23 @@
SetMutableBinding (
- _N_: a String,
- _V_: an ECMAScript language value,
- _S_: a Boolean,
+ _name_: a String,
+ _value_: an ECMAScript language value,
+ _strict_: a Boolean,
): either a normal completion containing ~unused~ or a throw completion
- for
- - an Object Environment Record _envRec_
+ - an Object Environment Record _envRecord_
- description
- - It attempts to set the value of the Environment Record's associated binding object's property whose name is _N_ to the value _V_. A property named _N_ normally already exists but if it does not or is not currently writable, error handling is determined by _S_.
+ - It attempts to set the value of the Environment Record's associated binding object's property whose name is _name_ to the value _value_. A property named _name_ normally already exists but if it does not or is not currently writable, error handling is determined by _strict_.
- 1. Let _bindingObject_ be _envRec_.[[BindingObject]].
- 1. Let _stillExists_ be ? HasProperty(_bindingObject_, _N_).
- 1. If _stillExists_ is *false* and _S_ is *true*, throw a *ReferenceError* exception.
- 1. Perform ? Set(_bindingObject_, _N_, _V_, _S_).
+ 1. Let _bindingObj_ be _envRecord_.[[BindingObject]].
+ 1. Let _stillExists_ be ? HasProperty(_bindingObj_, _name_).
+ 1. If _stillExists_ is *false* and _strict_ is *true*, throw a *ReferenceError* exception.
+ 1. Perform ? Set(_bindingObj_, _name_, _value_, _strict_).
1. Return ~unused~.
@@ -10388,42 +11038,43 @@
GetBindingValue (
- _N_: a String,
- _S_: a Boolean,
+ _name_: a String,
+ _strict_: a Boolean,
): either a normal completion containing an ECMAScript language value or a throw completion
- for
- - an Object Environment Record _envRec_
+ - an Object Environment Record _envRecord_
- description
- - It returns the value of its associated binding object's property whose name is _N_. The property should already exist but if it does not the result depends upon _S_.
+ - It returns the value of its associated binding object's property whose name is _name_. The property should already exist but if it does not the result depends upon _strict_.
- 1. Let _bindingObject_ be _envRec_.[[BindingObject]].
- 1. Let _value_ be ? HasProperty(_bindingObject_, _N_).
+ 1. Let _bindingObj_ be _envRecord_.[[BindingObject]].
+ 1. Let _value_ be ? HasProperty(_bindingObj_, _name_).
1. If _value_ is *false*, then
- 1. If _S_ is *false*, return *undefined*; otherwise throw a *ReferenceError* exception.
- 1. Return ? Get(_bindingObject_, _N_).
+ 1. If _strict_ is *false*, return *undefined*.
+ 1. Throw a *ReferenceError* exception.
+ 1. Return ? Get(_bindingObj_, _name_).
DeleteBinding (
- _N_: a String,
+ _name_: a String,
): either a normal completion containing a Boolean or a throw completion
- for
- - an Object Environment Record _envRec_
+ - an Object Environment Record _envRecord_
- description
- It can only delete bindings that correspond to properties of the environment object whose [[Configurable]] attribute have the value *true*.
- 1. Let _bindingObject_ be _envRec_.[[BindingObject]].
- 1. Return ? _bindingObject_.[[Delete]] (_N_).
+ 1. Let _bindingObj_ be _envRecord_.[[BindingObject]].
+ 1. Return ? _bindingObj_.[[Delete]](_name_) .
@@ -10431,7 +11082,7 @@
HasThisBinding ( ): *false*
- for
- - an Object Environment Record _envRec_
+ - an Object Environment Record _envRecord_
1. Return *false*.
@@ -10441,11 +11092,16 @@ HasThisBinding ( ): *false*
+
+ GetThisBinding ( )
+ The GetThisBinding concrete method of an Object Environment Record is never used within this specification.
+
+
HasSuperBinding ( ): *false*
- for
- - an Object Environment Record _envRec_
+ - an Object Environment Record _envRecord_
1. Return *false*.
@@ -10459,32 +11115,34 @@ HasSuperBinding ( ): *false*
WithBaseObject ( ): an Object or *undefined*
- for
- - an Object Environment Record _envRec_
+ - an Object Environment Record _envRecord_
- 1. If _envRec_.[[IsWithEnvironment]] is *true*, return _envRec_.[[BindingObject]].
- 1. Otherwise, return *undefined*.
+ 1. If _envRecord_.[[IsWithEnvironment]] is *true*, return _envRecord_.[[BindingObject]].
+ 1. Return *undefined*.
Function Environment Records
- A Function Environment Record is a Declarative Environment Record that is used to represent the top-level scope of a function and, if the function is not an |ArrowFunction|, provides a `this` binding. If a function is not an |ArrowFunction| function and references `super`, its Function Environment Record also contains the state that is used to perform `super` method invocations from within the function.
+ A Function Environment Record is a Declarative Environment Record that is used to represent the top-level scope of a function and, if the function is not an |ArrowFunction| function or |AsyncArrowFunction| function, provides a `this` binding. If a function is not an |ArrowFunction| function or |AsyncArrowFunction| function and references `super`, its Function Environment Record also contains the state that is used to perform `super` method invocations from within the function.
Function Environment Records have the additional state fields listed in
-
-
- Field Name
-
-
- Value
-
-
- Meaning
-
-
+
+
+
+ Field Name
+
+
+ Value
+
+
+ Meaning
+
+
+
[[ThisValue]]
@@ -10504,7 +11162,7 @@ Function Environment Records
~lexical~, ~initialized~, or ~uninitialized~
- If the value is ~lexical~, this is an |ArrowFunction| and does not have a local *this* value.
+ If the value is ~lexical~, this is an |ArrowFunction| or |AsyncArrowFunction| and does not have a local *this* value.
@@ -10523,7 +11181,7 @@ Function Environment Records
[[NewTarget]]
- an Object or *undefined*
+ a constructor or *undefined*
If this Environment Record was created by the [[Construct]] internal method, [[NewTarget]] is the value of the [[Construct]] _newTarget_ parameter. Otherwise, its value is *undefined*.
@@ -10531,61 +11189,25 @@ Function Environment Records
- Function Environment Records support all of the Declarative Environment Record methods listed in
-
-
-
-
- Method
-
-
- Purpose
-
-
-
-
- BindThisValue(V)
-
-
- Set the [[ThisValue]] and record that it has been initialized.
-
-
-
-
- GetThisBinding()
-
-
- Return the value of this Environment Record's `this` binding. Throws a *ReferenceError* if the `this` binding has not been initialized.
-
-
-
-
- GetSuperBase()
-
-
- Return the object that is the base for `super` property accesses bound in this Environment Record. The value *undefined* indicates that such accesses will produce runtime errors.
-
-
-
-
- The behaviour of the additional concrete specification methods for Function Environment Records is defined by the following algorithms:
+ Function Environment Records support all of the Declarative Environment Record methods listed in
-
+
BindThisValue (
- _V_: an ECMAScript language value,
- ): either a normal completion containing an ECMAScript language value or a throw completion
+ _envRecord_: a Function Environment Record,
+ _value_: an ECMAScript language value,
+ ): either a normal completion containing ~unused~ or a throw completion
- - for
- - a Function Environment Record _envRec_
+ - description
+ - It sets the _envRecord_.[[ThisValue]] and records that it has been initialized.
- 1. Assert: _envRec_.[[ThisBindingStatus]] is not ~lexical~.
- 1. If _envRec_.[[ThisBindingStatus]] is ~initialized~, throw a *ReferenceError* exception.
- 1. Set _envRec_.[[ThisValue]] to _V_.
- 1. Set _envRec_.[[ThisBindingStatus]] to ~initialized~.
- 1. Return _V_.
+ 1. Assert: _envRecord_.[[ThisBindingStatus]] is not ~lexical~.
+ 1. If _envRecord_.[[ThisBindingStatus]] is ~initialized~, throw a *ReferenceError* exception.
+ 1. Set _envRecord_.[[ThisValue]] to _value_.
+ 1. Set _envRecord_.[[ThisBindingStatus]] to ~initialized~.
+ 1. Return ~unused~.
@@ -10593,49 +11215,55 @@
HasThisBinding ( ): a Boolean
- for
- - a Function Environment Record _envRec_
+ - a Function Environment Record _envRecord_
- 1. If _envRec_.[[ThisBindingStatus]] is ~lexical~, return *false*; otherwise, return *true*.
+ 1. If _envRecord_.[[ThisBindingStatus]] is ~lexical~, return *false*.
+ 1. Return *true*.
-
- HasSuperBinding ( ): a Boolean
+
+ GetThisBinding ( ): either a normal completion containing an ECMAScript language value or a throw completion
- for
- - a Function Environment Record _envRec_
+ - a Function Environment Record _envRecord_
- 1. If _envRec_.[[ThisBindingStatus]] is ~lexical~, return *false*.
- 1. If _envRec_.[[FunctionObject]].[[HomeObject]] is *undefined*, return *false*; otherwise, return *true*.
+ 1. Assert: _envRecord_.[[ThisBindingStatus]] is not ~lexical~.
+ 1. If _envRecord_.[[ThisBindingStatus]] is ~uninitialized~, throw a *ReferenceError* exception.
+ 1. Return _envRecord_.[[ThisValue]].
-
- GetThisBinding ( ): either a normal completion containing an ECMAScript language value or a throw completion
+
+ HasSuperBinding ( ): a Boolean
- for
- - a Function Environment Record _envRec_
+ - a Function Environment Record _envRecord_
- 1. Assert: _envRec_.[[ThisBindingStatus]] is not ~lexical~.
- 1. If _envRec_.[[ThisBindingStatus]] is ~uninitialized~, throw a *ReferenceError* exception.
- 1. Return _envRec_.[[ThisValue]].
+ 1. If _envRecord_.[[ThisBindingStatus]] is ~lexical~, return *false*.
+ 1. If _envRecord_.[[FunctionObject]].[[HomeObject]] is *undefined*, return *false*.
+ 1. Return *true*.
-
- GetSuperBase ( ): either a normal completion containing either an Object, *null*, or *undefined*, or a throw completion
+
+
+ GetSuperBase (
+ _envRecord_: a Function Environment Record,
+ ): an Object, *null*, or *undefined*
+
- - for
- - a Function Environment Record _envRec_
+ - description
+ - It returns the object that is the base for `super` property accesses bound in _envRecord_. The value *undefined* indicates that such accesses will produce runtime errors.
- 1. Let _home_ be _envRec_.[[FunctionObject]].[[HomeObject]].
+ 1. Let _home_ be _envRecord_.[[FunctionObject]].[[HomeObject]].
1. If _home_ is *undefined*, return *undefined*.
- 1. Assert: _home_ is an Object.
- 1. Return ? _home_.[[GetPrototypeOf]] ().
+ 1. Assert: _home_ is an ordinary object.
+ 1. Return ! _home_.[[GetPrototypeOf]]().
@@ -10644,21 +11272,23 @@ GetSuperBase ( ): either a normal completion containing either an Object, *n
Global Environment Records
A Global Environment Record is used to represent the outer most scope that is shared by all of the ECMAScript |Script| elements that are processed in a common realm. A Global Environment Record provides the bindings for built-in globals (clause
A Global Environment Record is logically a single record but it is specified as a composite encapsulating an Object Environment Record and a Declarative Environment Record. The Object Environment Record has as its base object the global object of the associated Realm Record. This global object is the value returned by the Global Environment Record's GetThisBinding concrete method. The Object Environment Record component of a Global Environment Record contains the bindings for all built-in globals (clause
- Properties may be created directly on a global object. Hence, the Object Environment Record component of a Global Environment Record may contain both bindings created explicitly by |FunctionDeclaration|, |GeneratorDeclaration|, |AsyncFunctionDeclaration|, |AsyncGeneratorDeclaration|, or |VariableDeclaration| declarations and bindings created implicitly as properties of the global object. In order to identify which bindings were explicitly created using declarations, a Global Environment Record maintains a list of the names bound using its CreateGlobalVarBinding and CreateGlobalFunctionBinding concrete methods.
- Global Environment Records have the additional fields listed in
+ Properties may be created directly on a global object. Hence, the Object Environment Record component of a Global Environment Record may contain both bindings created explicitly by |FunctionDeclaration|, |GeneratorDeclaration|, |AsyncFunctionDeclaration|, |AsyncGeneratorDeclaration|, or |VariableDeclaration| declarations and bindings created implicitly as properties of the global object.
+ Global Environment Records have the additional fields listed in
-
-
- Field Name
-
-
- Value
-
-
- Meaning
-
-
+
+
+
+ Field Name
+
+
+ Value
+
+
+ Meaning
+
+
+
[[ObjectRecord]]
@@ -10692,256 +11322,165 @@ Global Environment Records
Contains bindings for all declarations in global code for the associated realm code except for |FunctionDeclaration|, |GeneratorDeclaration|, |AsyncFunctionDeclaration|, |AsyncGeneratorDeclaration|, and |VariableDeclaration| bindings.
-
-
- [[VarNames]]
-
-
- a List of Strings
-
-
- The string names bound by |FunctionDeclaration|, |GeneratorDeclaration|, |AsyncFunctionDeclaration|, |AsyncGeneratorDeclaration|, and |VariableDeclaration| declarations in global code for the associated realm.
-
-
-
-
-
-
- Method
-
-
- Purpose
-
-
-
-
- GetThisBinding()
-
-
- Return the value of this Environment Record's `this` binding.
-
-
-
-
- HasVarDeclaration (N)
-
-
- Determines if the argument identifier has a binding in this Environment Record that was created using a |VariableDeclaration|, |FunctionDeclaration|, |GeneratorDeclaration|, |AsyncFunctionDeclaration|, or |AsyncGeneratorDeclaration|.
-
-
-
-
- HasLexicalDeclaration (N)
-
-
- Determines if the argument identifier has a binding in this Environment Record that was created using a lexical declaration such as a |LexicalDeclaration| or a |ClassDeclaration|.
-
-
-
-
- HasRestrictedGlobalProperty (N)
-
-
- Determines if the argument is the name of a global object property that may not be shadowed by a global lexical binding.
-
-
-
-
- CanDeclareGlobalVar (N)
-
-
- Determines if a corresponding CreateGlobalVarBinding call would succeed if called for the same argument _N_.
-
-
-
-
- CanDeclareGlobalFunction (N)
-
-
- Determines if a corresponding CreateGlobalFunctionBinding call would succeed if called for the same argument _N_.
-
-
-
-
- CreateGlobalVarBinding(N, D)
-
-
- Used to create and initialize to *undefined* a global `var` binding in the [[ObjectRecord]] component of a Global Environment Record. The binding will be a mutable binding. The corresponding global object property will have attribute values appropriate for a `var`. The String value _N_ is the bound name. If _D_ is *true*, the binding may be deleted. Logically equivalent to CreateMutableBinding followed by a SetMutableBinding but it allows var declarations to receive special treatment.
-
-
-
-
- CreateGlobalFunctionBinding(N, V, D)
-
-
- Create and initialize a global `function` binding in the [[ObjectRecord]] component of a Global Environment Record. The binding will be a mutable binding. The corresponding global object property will have attribute values appropriate for a `function`. The String value _N_ is the bound name. _V_ is the initialization value. If the Boolean argument _D_ is *true*, the binding may be deleted. Logically equivalent to CreateMutableBinding followed by a SetMutableBinding but it allows function declarations to receive special treatment.
-
-
-
-
- The behaviour of the concrete specification methods for Global Environment Records is defined by the following algorithms.
HasBinding (
- _N_: a String,
+ _name_: a String,
): either a normal completion containing a Boolean or a throw completion
- for
- - a Global Environment Record _envRec_
+ - a Global Environment Record _envRecord_
- description
- It determines if the argument identifier is one of the identifiers bound by the record.
- 1. Let _DclRec_ be _envRec_.[[DeclarativeRecord]].
- 1. If ! _DclRec_.HasBinding(_N_) is *true*, return *true*.
- 1. Let _ObjRec_ be _envRec_.[[ObjectRecord]].
- 1. Return ? _ObjRec_.HasBinding (_N_).
+ 1. Let _declRecord_ be _envRecord_.[[DeclarativeRecord]].
+ 1. If ! _declRecord_.HasBinding(_name_) is *true*, return *true*.
+ 1. Let _objRecord_ be _envRecord_.[[ObjectRecord]].
+ 1. Return ? _objRecord_.HasBinding(_name_) .
CreateMutableBinding (
- _N_: a String,
- _D_: a Boolean,
+ _name_: a String,
+ _deletable_: a Boolean,
): either a normal completion containing ~unused~ or a throw completion
- for
- - a Global Environment Record _envRec_
+ - a Global Environment Record _envRecord_
- description
- - It creates a new mutable binding for the name _N_ that is uninitialized. The binding is created in the associated DeclarativeRecord. A binding for _N_ must not already exist in the DeclarativeRecord. If _D_ is *true*, the new binding is marked as being subject to deletion.
+ - It creates a new mutable binding for the name _name_ that is uninitialized. The binding is created in the associated DeclarativeRecord. A binding for _name_ must not already exist in the DeclarativeRecord. If _deletable_ is *true*, the new binding is marked as being subject to deletion.
- 1. Let _DclRec_ be _envRec_.[[DeclarativeRecord]].
- 1. If ! _DclRec_.HasBinding(_N_) is *true*, throw a *TypeError* exception.
- 1. Return ! _DclRec_.CreateMutableBinding(_N_, _D_).
+ 1. Let _declRecord_ be _envRecord_.[[DeclarativeRecord]].
+ 1. If ! _declRecord_.HasBinding(_name_) is *true*, throw a *TypeError* exception.
+ 1. Return ! _declRecord_.CreateMutableBinding(_name_, _deletable_).
CreateImmutableBinding (
- _N_: a String,
- _S_: a Boolean,
+ _name_: a String,
+ _strict_: a Boolean,
): either a normal completion containing ~unused~ or a throw completion
- for
- - a Global Environment Record _envRec_
+ - a Global Environment Record _envRecord_
- description
- - It creates a new immutable binding for the name _N_ that is uninitialized. A binding must not already exist in this Environment Record for _N_. If _S_ is *true*, the new binding is marked as a strict binding.
+ - It creates a new immutable binding for the name _name_ that is uninitialized. A binding must not already exist in this Environment Record for _name_. If _strict_ is *true*, the new binding is marked as a strict binding.
- 1. Let _DclRec_ be _envRec_.[[DeclarativeRecord]].
- 1. If ! _DclRec_.HasBinding(_N_) is *true*, throw a *TypeError* exception.
- 1. Return ! _DclRec_.CreateImmutableBinding(_N_, _S_).
+ 1. Let _declRecord_ be _envRecord_.[[DeclarativeRecord]].
+ 1. If ! _declRecord_.HasBinding(_name_) is *true*, throw a *TypeError* exception.
+ 1. Return ! _declRecord_.CreateImmutableBinding(_name_, _strict_).
InitializeBinding (
- _N_: a String,
- _V_: an ECMAScript language value,
+ _name_: a String,
+ _value_: an ECMAScript language value,
): either a normal completion containing ~unused~ or a throw completion
- for
- - a Global Environment Record _envRec_
+ - a Global Environment Record _envRecord_
- description
- - It is used to set the bound value of the current binding of the identifier whose name is _N_ to the value _V_. An uninitialized binding for _N_ must already exist.
+ - It is used to set the bound value of the current binding of the identifier whose name is _name_ to the value _value_. An uninitialized binding for _name_ must already exist.
- 1. Let _DclRec_ be _envRec_.[[DeclarativeRecord]].
- 1. If ! _DclRec_.HasBinding(_N_) is *true*, then
- 1. Return ! _DclRec_.InitializeBinding(_N_, _V_).
+ 1. Let _declRecord_ be _envRecord_.[[DeclarativeRecord]].
+ 1. If ! _declRecord_.HasBinding(_name_) is *true*, then
+ 1. Return ! _declRecord_.InitializeBinding(_name_, _value_).
1. Assert: If the binding exists, it must be in the Object Environment Record.
- 1. Let _ObjRec_ be _envRec_.[[ObjectRecord]].
- 1. Return ? _ObjRec_.InitializeBinding (_N_, _V_).
+ 1. Let _objRecord_ be _envRecord_.[[ObjectRecord]].
+ 1. Return ? _objRecord_.InitializeBinding(_name_, _value_) .
SetMutableBinding (
- _N_: a String,
- _V_: an ECMAScript language value,
- _S_: a Boolean,
+ _name_: a String,
+ _value_: an ECMAScript language value,
+ _strict_: a Boolean,
): either a normal completion containing ~unused~ or a throw completion
- for
- - a Global Environment Record _envRec_
+ - a Global Environment Record _envRecord_
- description
- - It attempts to change the bound value of the current binding of the identifier whose name is _N_ to the value _V_. If the binding is an immutable binding and _S_ is *true*, a *TypeError* is thrown. A property named _N_ normally already exists but if it does not or is not currently writable, error handling is determined by _S_.
+ - It attempts to change the bound value of the current binding of the identifier whose name is _name_ to the value _value_. If the binding is an immutable binding and _strict_ is *true*, a *TypeError* is thrown. A binding named _name_ normally already exists but if it does not or is not currently writable, error handling is determined by _strict_.
- 1. Let _DclRec_ be _envRec_.[[DeclarativeRecord]].
- 1. If ! _DclRec_.HasBinding(_N_) is *true*, then
- 1. Return ? _DclRec_.SetMutableBinding(_N_, _V_, _S_).
- 1. Let _ObjRec_ be _envRec_.[[ObjectRecord]].
- 1. Return ? _ObjRec_.SetMutableBinding (_N_, _V_, _S_).
+ 1. Let _declRecord_ be _envRecord_.[[DeclarativeRecord]].
+ 1. If ! _declRecord_.HasBinding(_name_) is *true*, then
+ 1. Return ? _declRecord_.SetMutableBinding(_name_, _value_, _strict_).
+ 1. Let _objRecord_ be _envRecord_.[[ObjectRecord]].
+ 1. Return ? _objRecord_.SetMutableBinding(_name_, _value_, _strict_) .
GetBindingValue (
- _N_: a String,
- _S_: a Boolean,
+ _name_: a String,
+ _strict_: a Boolean,
): either a normal completion containing an ECMAScript language value or a throw completion
- for
- - a Global Environment Record _envRec_
+ - a Global Environment Record _envRecord_
- description
- - It returns the value of its bound identifier whose name is _N_. If the binding is an uninitialized binding throw a *ReferenceError* exception. A property named _N_ normally already exists but if it does not or is not currently writable, error handling is determined by _S_.
+ - It returns the value of its bound identifier whose name is _name_. If the binding is an uninitialized binding, it will throw a *ReferenceError* exception. A binding named _name_ normally already exists but if it does not or is not currently writable, error handling is determined by _strict_.
- 1. Let _DclRec_ be _envRec_.[[DeclarativeRecord]].
- 1. If ! _DclRec_.HasBinding(_N_) is *true*, then
- 1. Return ? _DclRec_.GetBindingValue(_N_, _S_).
- 1. Let _ObjRec_ be _envRec_.[[ObjectRecord]].
- 1. Return ? _ObjRec_.GetBindingValue (_N_, _S_).
+ 1. Let _declRecord_ be _envRecord_.[[DeclarativeRecord]].
+ 1. If ! _declRecord_.HasBinding(_name_) is *true*, then
+ 1. Return ? _declRecord_.GetBindingValue(_name_, _strict_).
+ 1. Let _objRecord_ be _envRecord_.[[ObjectRecord]].
+ 1. Return ? _objRecord_.GetBindingValue(_name_, _strict_) .
DeleteBinding (
- _N_: a String,
+ _name_: a String,
): either a normal completion containing a Boolean or a throw completion
- for
- - a Global Environment Record _envRec_
+ - a Global Environment Record _envRecord_
- description
- It can only delete bindings that have been explicitly designated as being subject to deletion.
- 1. Let _DclRec_ be _envRec_.[[DeclarativeRecord]].
- 1. If ! _DclRec_.HasBinding(_N_) is *true*, then
- 1. Return ! _DclRec_.DeleteBinding(_N_).
- 1. Let _ObjRec_ be _envRec_.[[ObjectRecord]].
- 1. Let _globalObject_ be _ObjRec_.[[BindingObject]].
- 1. Let _existingProp_ be ? HasOwnProperty(_globalObject_, _N_).
- 1. If _existingProp_ is *true*, then
- 1. Let _status_ be ? _ObjRec_.DeleteBinding (_N_).
- 1. If _status_ is *true* and _envRec_.[[VarNames]] contains _N_, then
- 1. Remove _N_ from _envRec_.[[VarNames]].
- 1. Return _status_.
+ 1. Let _declRecord_ be _envRecord_.[[DeclarativeRecord]].
+ 1. If ! _declRecord_.HasBinding(_name_) is *true*, then
+ 1. Return ! _declRecord_.DeleteBinding(_name_).
+ 1. Let _objRecord_ be _envRecord_.[[ObjectRecord]].
+ 1. Let _globalObj_ be _objRecord_.[[BindingObject]].
+ 1. Let _existingProperty_ be ? HasOwnProperty(_globalObj_, _name_).
+ 1. If _existingProperty_ is *true*, then
+ 1. Return ? _objRecord_.DeleteBinding(_name_) .
1. Return *true*.
@@ -10950,7 +11489,7 @@
HasThisBinding ( ): *true*
- for
- - a Global Environment Record _envRec_
+ - a Global Environment Record _envRecord_
1. Return *true*.
@@ -10960,11 +11499,22 @@ HasThisBinding ( ): *true*
+
+ GetThisBinding ( ): a normal completion containing an Object
+
+ - for
+ - a Global Environment Record _envRecord_
+
+
+ 1. Return _envRecord_.[[GlobalThisValue]].
+
+
+
HasSuperBinding ( ): *false*
- for
- - a Global Environment Record _envRec_
+ - a Global Environment Record _envRecord_
1. Return *false*.
@@ -10978,82 +11528,47 @@ HasSuperBinding ( ): *false*
WithBaseObject ( ): *undefined*
- for
- - a Global Environment Record _envRec_
+ - a Global Environment Record _envRecord_
1. Return *undefined*.
-
- GetThisBinding ( ): a normal completion containing an Object
-
- - for
- - a Global Environment Record _envRec_
-
-
- 1. Return _envRec_.[[GlobalThisValue]].
-
-
-
-
-
- HasVarDeclaration (
- _N_: a String,
- ): a Boolean
-
-
- - for
- - a Global Environment Record _envRec_
-
- - description
- - It determines if the argument identifier has a binding in this record that was created using a |VariableStatement| or a |FunctionDeclaration|.
-
-
- 1. Let _varDeclaredNames_ be _envRec_.[[VarNames]].
- 1. If _varDeclaredNames_ contains _N_, return *true*.
- 1. Return *false*.
-
-
-
-
+
HasLexicalDeclaration (
- _N_: a String,
+ _envRecord_: a Global Environment Record,
+ _name_: a String,
): a Boolean
- - for
- - a Global Environment Record _envRec_
-
- description
- - It determines if the argument identifier has a binding in this record that was created using a lexical declaration such as a |LexicalDeclaration| or a |ClassDeclaration|.
+ - It determines if the argument identifier has a binding in _envRecord_ that was created using a lexical declaration such as a |LexicalDeclaration| or a |ClassDeclaration|.
- 1. Let _DclRec_ be _envRec_.[[DeclarativeRecord]].
- 1. Return ! _DclRec_.HasBinding(_N_).
+ 1. Let _declRecord_ be _envRecord_.[[DeclarativeRecord]].
+ 1. Return ! _declRecord_.HasBinding(_name_).
-
+
HasRestrictedGlobalProperty (
- _N_: a String,
+ _envRecord_: a Global Environment Record,
+ _name_: a String,
): either a normal completion containing a Boolean or a throw completion
- - for
- - a Global Environment Record _envRec_
-
- description
- It determines if the argument identifier is the name of a property of the global object that must not be shadowed by a global lexical binding.
- 1. Let _ObjRec_ be _envRec_.[[ObjectRecord]].
- 1. Let _globalObject_ be _ObjRec_.[[BindingObject]].
- 1. Let _existingProp_ be ? _globalObject_.[[GetOwnProperty]] (_N_).
- 1. If _existingProp_ is *undefined*, return *false*.
- 1. If _existingProp_.[[Configurable]] is *true*, return *false*.
+ 1. Let _objRecord_ be _envRecord_.[[ObjectRecord]].
+ 1. Let _globalObj_ be _objRecord_.[[BindingObject]].
+ 1. Let _existingProperty_ be ? _globalObj_.[[GetOwnProperty]](_name_) .
+ 1. If _existingProperty_ is *undefined*, return *false*.
+ 1. If _existingProperty_.[[Configurable]] is *true*, return *false*.
1. Return *true*.
@@ -11061,111 +11576,99 @@
-
+
CanDeclareGlobalVar (
- _N_: a String,
+ _envRecord_: a Global Environment Record,
+ _name_: a String,
): either a normal completion containing a Boolean or a throw completion
- - for
- - a Global Environment Record _envRec_
-
- description
- - It determines if a corresponding CreateGlobalVarBinding call would succeed if called for the same argument _N_. Redundant var declarations and var declarations for pre-existing global object properties are allowed.
+ - It determines if a corresponding CreateGlobalVarBinding call would succeed if called for the same argument _name_. Redundant var declarations and var declarations for pre-existing global object properties are allowed.
- 1. Let _ObjRec_ be _envRec_.[[ObjectRecord]].
- 1. Let _globalObject_ be _ObjRec_.[[BindingObject]].
- 1. Let _hasProperty_ be ? HasOwnProperty(_globalObject_, _N_).
+ 1. Let _objRecord_ be _envRecord_.[[ObjectRecord]].
+ 1. Let _globalObj_ be _objRecord_.[[BindingObject]].
+ 1. Let _hasProperty_ be ? HasOwnProperty(_globalObj_, _name_).
1. If _hasProperty_ is *true*, return *true*.
- 1. Return ? IsExtensible(_globalObject_).
+ 1. Return ? IsExtensible(_globalObj_).
-
+
CanDeclareGlobalFunction (
- _N_: a String,
+ _envRecord_: a Global Environment Record,
+ _name_: a String,
): either a normal completion containing a Boolean or a throw completion
- - for
- - a Global Environment Record _envRec_
-
- description
- - It determines if a corresponding CreateGlobalFunctionBinding call would succeed if called for the same argument _N_.
+ - It determines if a corresponding CreateGlobalFunctionBinding call would succeed if called for the same argument _name_.
- 1. Let _ObjRec_ be _envRec_.[[ObjectRecord]].
- 1. Let _globalObject_ be _ObjRec_.[[BindingObject]].
- 1. Let _existingProp_ be ? _globalObject_.[[GetOwnProperty]] (_N_).
- 1. If _existingProp_ is *undefined*, return ? IsExtensible(_globalObject_).
- 1. If _existingProp_.[[Configurable]] is *true*, return *true*.
- 1. If IsDataDescriptor(_existingProp_) is *true* and _existingProp_ has attribute values { [[Writable]]: *true*, [[Enumerable]]: *true* }, return *true*.
+ 1. Let _objRecord_ be _envRecord_.[[ObjectRecord]].
+ 1. Let _globalObj_ be _objRecord_.[[BindingObject]].
+ 1. Let _existingProperty_ be ? _globalObj_.[[GetOwnProperty]](_name_) .
+ 1. If _existingProperty_ is *undefined*, return ? IsExtensible(_globalObj_).
+ 1. If _existingProperty_.[[Configurable]] is *true*, return *true*.
+ 1. If IsDataDescriptor(_existingProperty_) is *true* and _existingProperty_ has attribute values { [[Writable]]: *true*, [[Enumerable]]: *true* }, return *true*.
1. Return *false*.
-
+
CreateGlobalVarBinding (
- _N_: a String,
- _D_: a Boolean,
+ _envRecord_: a Global Environment Record,
+ _name_: a String,
+ _deletable_: a Boolean,
): either a normal completion containing ~unused~ or a throw completion
- - for
- - a Global Environment Record _envRec_
-
- description
- - It creates and initializes a mutable binding in the associated Object Environment Record and records the bound name in the associated [[VarNames]] List. If a binding already exists, it is reused and assumed to be initialized.
+ - It creates and initializes a mutable binding in the associated Object Environment Record. If a binding already exists, it is reused and assumed to be initialized.
- 1. Let _ObjRec_ be _envRec_.[[ObjectRecord]].
- 1. Let _globalObject_ be _ObjRec_.[[BindingObject]].
- 1. Let _hasProperty_ be ? HasOwnProperty(_globalObject_, _N_).
- 1. Let _extensible_ be ? IsExtensible(_globalObject_).
+ 1. Let _objRecord_ be _envRecord_.[[ObjectRecord]].
+ 1. Let _globalObj_ be _objRecord_.[[BindingObject]].
+ 1. Let _hasProperty_ be ? HasOwnProperty(_globalObj_, _name_).
+ 1. Let _extensible_ be ? IsExtensible(_globalObj_).
1. If _hasProperty_ is *false* and _extensible_ is *true*, then
- 1. Perform ? _ObjRec_.CreateMutableBinding (_N_, _D_).
- 1. Perform ? _ObjRec_.InitializeBinding (_N_, *undefined*).
- 1. If _envRec_.[[VarNames]] does not contain _N_, then
- 1. Append _N_ to _envRec_.[[VarNames]].
+ 1. Perform ? _objRecord_.CreateMutableBinding(_name_, _deletable_) .
+ 1. Perform ? _objRecord_.InitializeBinding(_name_, *undefined*) .
1. Return ~unused~.
-
+
CreateGlobalFunctionBinding (
- _N_: a String,
- _V_: an ECMAScript language value,
- _D_: a Boolean,
+ _envRecord_: a Global Environment Record,
+ _name_: a String,
+ _value_: an ECMAScript function object,
+ _deletable_: a Boolean,
): either a normal completion containing ~unused~ or a throw completion
- - for
- - a Global Environment Record _envRec_
-
- description
- - It creates and initializes a mutable binding in the associated Object Environment Record and records the bound name in the associated [[VarNames]] List. If a binding already exists, it is replaced.
+ - It creates and initializes a mutable binding in the associated Object Environment Record. If a binding already exists, it is replaced.
- 1. Let _ObjRec_ be _envRec_.[[ObjectRecord]].
- 1. Let _globalObject_ be _ObjRec_.[[BindingObject]].
- 1. Let _existingProp_ be ? _globalObject_.[[GetOwnProperty]] (_N_).
- 1. If _existingProp_ is *undefined* or _existingProp_.[[Configurable]] is *true*, then
- 1. Let _desc_ be the PropertyDescriptor { [[Value]]: _V_, [[Writable]]: *true*, [[Enumerable]]: *true*, [[Configurable]]: _D_ }.
+ 1. Let _objRecord_ be _envRecord_.[[ObjectRecord]].
+ 1. Let _globalObj_ be _objRecord_.[[BindingObject]].
+ 1. Let _existingProperty_ be ? _globalObj_.[[GetOwnProperty]](_name_) .
+ 1. If _existingProperty_ is *undefined* or _existingProperty_.[[Configurable]] is *true*, then
+ 1. Let _propertyDesc_ be the PropertyDescriptor { [[Value]]: _value_, [[Writable]]: *true*, [[Enumerable]]: *true*, [[Configurable]]: _deletable_ }.
1. Else,
- 1. Let _desc_ be the PropertyDescriptor { [[Value]]: _V_ }.
- 1. Perform ? DefinePropertyOrThrow(_globalObject_, _N_, _desc_).
- 1. [id="step-createglobalfunctionbinding-set"] Perform ? Set(_globalObject_, _N_, _V_, *false*).
- 1. If _envRec_.[[VarNames]] does not contain _N_, then
- 1. Append _N_ to _envRec_.[[VarNames]].
+ 1. Let _propertyDesc_ be the PropertyDescriptor { [[Value]]: _value_ }.
+ 1. Perform ? DefinePropertyOrThrow(_globalObj_, _name_, _propertyDesc_).
+ 1. [id="step-createglobalfunctionbinding-set"] Perform ? Set(_globalObj_, _name_, _value_, *false*).
1. Return ~unused~.
- Global function declarations are always represented as own properties of the global object. If possible, an existing own property is reconfigured to have a standard set of attribute values. Step
+ Global function declarations are always represented as own properties of the global object. If possible, an existing own property is reconfigured to have a standard set of attribute values. Step
@@ -11173,69 +11676,40 @@
Module Environment Records
A Module Environment Record is a Declarative Environment Record that is used to represent the outer scope of an ECMAScript |Module|. In additional to normal mutable and immutable bindings, Module Environment Records also provide immutable import bindings which are bindings that provide indirect access to a target binding that exists in another Environment Record.
- Module Environment Records support all of the Declarative Environment Record methods listed in
-
-
-
-
- Method
-
-
- Purpose
-
-
-
-
- CreateImportBinding(N, M, N2)
-
-
- Create an immutable indirect binding in a Module Environment Record. The String value _N_ is the text of the bound name. _M_ is a Module Record, and _N2_ is a binding that exists in _M_'s Module Environment Record.
-
-
-
-
- GetThisBinding()
-
-
- Return the value of this Environment Record's `this` binding.
-
-
-
-
- The behaviour of the additional concrete specification methods for Module Environment Records are defined by the following algorithms:
+ Module Environment Records support all of the Declarative Environment Record methods listed in
GetBindingValue (
- _N_: a String,
- _S_: a Boolean,
+ _name_: a String,
+ _strict_: a Boolean,
): either a normal completion containing an ECMAScript language value or a throw completion
- for
- - a Module Environment Record _envRec_
+ - a Module Environment Record _envRecord_
- description
- - It returns the value of its bound identifier whose name is _N_. However, if the binding is an indirect binding the value of the target binding is returned. If the binding exists but is uninitialized a *ReferenceError* is thrown.
+ - It returns the value of its bound identifier whose name is _name_. However, if the binding is an indirect binding the value of the target binding is returned. If the binding exists but is uninitialized a *ReferenceError* is thrown.
- 1. Assert: _S_ is *true*.
- 1. Assert: _envRec_ has a binding for _N_.
- 1. If the binding for _N_ is an indirect binding, then
- 1. Let _M_ and _N2_ be the indirection values provided when this binding for _N_ was created.
- 1. Let _targetEnv_ be _M_.[[Environment]].
+ 1. Assert: _strict_ is *true*.
+ 1. Assert: _envRecord_ has a binding for _name_.
+ 1. If the binding for _name_ is an indirect binding, then
+ 1. Let _module_ and _targetName_ be the indirection values provided when this binding for _name_ was created.
+ 1. Let _targetEnv_ be _module_.[[Environment]].
1. If _targetEnv_ is ~empty~, throw a *ReferenceError* exception.
- 1. Return ? _targetEnv_.GetBindingValue (_N2_, *true*).
- 1. If the binding for _N_ in _envRec_ is an uninitialized binding, throw a *ReferenceError* exception.
- 1. Return the value currently bound to _N_ in _envRec_.
+ 1. Return ? _targetEnv_.GetBindingValue(_targetName_, *true*) .
+ 1. If the binding for _name_ in _envRecord_ is an uninitialized binding, throw a *ReferenceError* exception.
+ 1. Return the value currently bound to _name_ in _envRecord_.
- _S_ will always be *true* because a |Module| is always strict mode code.
+ _strict_ will always be *true* because a |Module| is always strict mode code.
- DeleteBinding ( _N_ )
+ DeleteBinding ( _name_ )
The DeleteBinding concrete method of a Module Environment Record is never used within this specification.
Module Environment Records are only used within strict code and an early error rule prevents the delete operator, in strict code, from being applied to a Reference Record that would resolve to a Module Environment Record binding. See
@@ -11246,7 +11720,7 @@ DeleteBinding ( _N_ )
HasThisBinding ( ): *true*
- for
- - a Module Environment Record _envRec_
+ - a Module Environment Record _envRecord_
1. Return *true*.
@@ -11260,32 +11734,30 @@ HasThisBinding ( ): *true*
GetThisBinding ( ): a normal completion containing *undefined*
- for
- - a Module Environment Record _envRec_
+ - a Module Environment Record _envRecord_
1. Return *undefined*.
-
+
CreateImportBinding (
- _N_: a String,
- _M_: a Module Record,
- _N2_: a String,
+ _envRecord_: a Module Environment Record,
+ _name_: a String,
+ _targetModule_: a Module Record,
+ _targetName_: a String,
): ~unused~
- - for
- - a Module Environment Record _envRec_
-
- description
- - It creates a new initialized immutable indirect binding for the name _N_. A binding must not already exist in this Environment Record for _N_. _N2_ is the name of a binding that exists in _M_'s Module Environment Record. Accesses to the value of the new binding will indirectly access the bound value of the target binding.
+ - It creates a new initialized immutable indirect binding for the name _name_. A binding must not already exist in _envRecord_ for _name_. _targetName_ is the name of a binding that exists in _targetModule_'s Module Environment Record. Accesses to the value of the new binding will indirectly access the bound value of the target binding.
- 1. Assert: _envRec_ does not already have a binding for _N_.
- 1. Assert: When _M_.[[Environment]] is instantiated, it will have a direct binding for _N2_.
- 1. Create an immutable indirect binding in _envRec_ for _N_ that references _M_ and _N2_ as its target binding and record that the binding is initialized.
+ 1. Assert: _envRecord_ does not already have a binding for _name_.
+ 1. Assert: When _targetModule_.[[Environment]] is instantiated, it will have a direct binding for _targetName_.
+ 1. Create an immutable indirect binding in _envRecord_ for _name_ that references _targetModule_ and _targetName_ as its target binding and record that the binding is initialized.
1. Return ~unused~.
@@ -11299,7 +11771,7 @@ Environment Record Operations
GetIdentifierReference (
- _env_: an Environment Record or *null*,
+ _envRecord_: an Environment Record or *null*,
_name_: a String,
_strict_: a Boolean,
): either a normal completion containing a Reference Record or a throw completion
@@ -11307,105 +11779,106 @@
- 1. If _env_ is *null*, then
+ 1. If _envRecord_ is *null*, then
1. Return the Reference Record { [[Base]]: ~unresolvable~, [[ReferencedName]]: _name_, [[Strict]]: _strict_, [[ThisValue]]: ~empty~ }.
- 1. Let _exists_ be ? _env_.HasBinding (_name_).
+ 1. Let _exists_ be ? _envRecord_.HasBinding(_name_) .
1. If _exists_ is *true*, then
- 1. Return the Reference Record { [[Base]]: _env_, [[ReferencedName]]: _name_, [[Strict]]: _strict_, [[ThisValue]]: ~empty~ }.
- 1. Else,
- 1. Let _outer_ be _env_.[[OuterEnv]].
- 1. Return ? GetIdentifierReference(_outer_, _name_, _strict_).
+ 1. Return the Reference Record { [[Base]]: _envRecord_, [[ReferencedName]]: _name_, [[Strict]]: _strict_, [[ThisValue]]: ~empty~ }.
+ 1. Let _outer_ be _envRecord_.[[OuterEnv]].
+ 1. Return ? GetIdentifierReference(_outer_, _name_, _strict_).
NewDeclarativeEnvironment (
- _E_: an Environment Record or *null*,
+ _outerEnv_: an Environment Record or *null*,
): a Declarative Environment Record
- 1. Let _env_ be a new Declarative Environment Record containing no bindings.
- 1. Set _env_.[[OuterEnv]] to _E_.
- 1. Return _env_.
+ 1. Let _envRecord_ be a new Declarative Environment Record containing no bindings.
+ 1. Set _envRecord_.[[OuterEnv]] to _outerEnv_.
+ 1. Set _envRecord_.[[DisposableResourceStack]] to a new empty List.
+ 1. Return _envRecord_.
NewObjectEnvironment (
- _O_: an Object,
- _W_: a Boolean,
- _E_: an Environment Record or *null*,
+ _obj_: an Object,
+ _isWithEnv_: a Boolean,
+ _outerEnv_: an Environment Record or *null*,
): an Object Environment Record
- 1. Let _env_ be a new Object Environment Record.
- 1. Set _env_.[[BindingObject]] to _O_.
- 1. Set _env_.[[IsWithEnvironment]] to _W_.
- 1. Set _env_.[[OuterEnv]] to _E_.
- 1. Return _env_.
+ 1. Let _envRecord_ be a new Object Environment Record.
+ 1. Set _envRecord_.[[BindingObject]] to _obj_.
+ 1. Set _envRecord_.[[IsWithEnvironment]] to _isWithEnv_.
+ 1. Set _envRecord_.[[OuterEnv]] to _outerEnv_.
+ 1. Return _envRecord_.
NewFunctionEnvironment (
- _F_: an ECMAScript function object,
+ _func_: an ECMAScript function object,
_newTarget_: an Object or *undefined*,
): a Function Environment Record
- 1. Let _env_ be a new Function Environment Record containing no bindings.
- 1. Set _env_.[[FunctionObject]] to _F_.
- 1. If _F_.[[ThisMode]] is ~lexical~, set _env_.[[ThisBindingStatus]] to ~lexical~.
- 1. Else, set _env_.[[ThisBindingStatus]] to ~uninitialized~.
- 1. Set _env_.[[NewTarget]] to _newTarget_.
- 1. Set _env_.[[OuterEnv]] to _F_.[[Environment]].
- 1. Return _env_.
+ 1. Let _envRecord_ be a new Function Environment Record containing no bindings.
+ 1. Set _envRecord_.[[FunctionObject]] to _func_.
+ 1. If _func_.[[ThisMode]] is ~lexical~, set _envRecord_.[[ThisBindingStatus]] to ~lexical~.
+ 1. Else, set _envRecord_.[[ThisBindingStatus]] to ~uninitialized~.
+ 1. Set _envRecord_.[[NewTarget]] to _newTarget_.
+ 1. Set _envRecord_.[[OuterEnv]] to _func_.[[Environment]].
+ 1. Set _envRecord_.[[DisposableResourceStack]] to a new empty List.
+ 1. Return _envRecord_.
NewGlobalEnvironment (
- _G_: an Object,
+ _obj_: an Object,
_thisValue_: an Object,
): a Global Environment Record
- 1. Let _objRec_ be NewObjectEnvironment(_G_, *false*, *null*).
- 1. Let _dclRec_ be NewDeclarativeEnvironment(*null*).
- 1. Let _env_ be a new Global Environment Record.
- 1. Set _env_.[[ObjectRecord]] to _objRec_.
- 1. Set _env_.[[GlobalThisValue]] to _thisValue_.
- 1. Set _env_.[[DeclarativeRecord]] to _dclRec_.
- 1. Set _env_.[[VarNames]] to a new empty List.
- 1. Set _env_.[[OuterEnv]] to *null*.
- 1. Return _env_.
+ 1. Let _objRecord_ be NewObjectEnvironment(_obj_, *false*, *null*).
+ 1. Let _declRecord_ be NewDeclarativeEnvironment(*null*).
+ 1. Let _envRecord_ be a new Global Environment Record.
+ 1. Set _envRecord_.[[ObjectRecord]] to _objRecord_.
+ 1. Set _envRecord_.[[GlobalThisValue]] to _thisValue_.
+ 1. Set _envRecord_.[[DeclarativeRecord]] to _declRecord_.
+ 1. Set _envRecord_.[[OuterEnv]] to *null*.
+ 1. Return _envRecord_.
NewModuleEnvironment (
- _E_: an Environment Record,
+ _outerEnv_: a Global Environment Record,
): a Module Environment Record
- 1. Let _env_ be a new Module Environment Record containing no bindings.
- 1. Set _env_.[[OuterEnv]] to _E_.
- 1. Return _env_.
+ 1. Let _envRecord_ be a new Module Environment Record containing no bindings.
+ 1. Set _envRecord_.[[OuterEnv]] to _outerEnv_.
+ 1. Set _envRecord_.[[DisposableResourceStack]] to a new empty List.
+ 1. Return _envRecord_.
@@ -11462,34 +11935,34 @@ PrivateEnvironment Record Operations
NewPrivateEnvironment (
- _outerPrivEnv_: a PrivateEnvironment Record or *null*,
+ _outerPrivateEnv_: a PrivateEnvironment Record or *null*,
): a PrivateEnvironment Record
1. Let _names_ be a new empty List.
- 1. Return the PrivateEnvironment Record { [[OuterPrivateEnvironment]]: _outerPrivEnv_, [[Names]]: _names_ }.
+ 1. Return the PrivateEnvironment Record { [[OuterPrivateEnvironment]]: _outerPrivateEnv_, [[Names]]: _names_ }.
ResolvePrivateIdentifier (
- _privEnv_: a PrivateEnvironment Record,
+ _privateEnv_: a PrivateEnvironment Record,
_identifier_: a String,
): a Private Name
- 1. Let _names_ be _privEnv_.[[Names]].
- 1. For each Private Name _pn_ of _names_, do
- 1. If _pn_.[[Description]] is _identifier_, then
- 1. Return _pn_.
- 1. Let _outerPrivEnv_ be _privEnv_.[[OuterPrivateEnvironment]].
- 1. Assert: _outerPrivEnv_ is not *null*.
- 1. Return ResolvePrivateIdentifier(_outerPrivEnv_, _identifier_).
+ 1. Let _names_ be _privateEnv_.[[Names]].
+ 1. For each Private Name _privateName_ of _names_, do
+ 1. If _privateName_.[[Description]] is _identifier_, then
+ 1. Return _privateName_.
+ 1. Let _outerPrivateEnv_ be _privateEnv_.[[OuterPrivateEnvironment]].
+ 1. Assert: _outerPrivateEnv_ is not *null*.
+ 1. Return ResolvePrivateIdentifier(_outerPrivateEnv_, _identifier_).
@@ -11501,17 +11974,19 @@ Realms
A realm is represented in this specification as a Realm Record with the fields specified in
-
-
- Field Name
-
-
- Value
-
-
- Meaning
-
-
+
+
+
+ Field Name
+
+
+ Value
+
+
+ Meaning
+
+
+
[[AgentSignifier]]
@@ -11539,7 +12014,7 @@ Realms
[[GlobalObject]]
- an Object or *undefined*
+ an Object
The global object for this realm
@@ -11573,10 +12048,10 @@ Realms
[[LoadedModules]]
- a List of Records with fields [[Specifier]] (a String) and [[Module]] (a Module Record)
+ a List of LoadedModuleRequest Records
- A map from the specifier strings imported by this realm to the resolved Module Record. The list does not contain two different Records with the same [[Specifier]].
+ A map from the specifier strings imported by this realm to the resolved Module Record. The list does not contain two different Records _r1_ and _r2_ such that ModuleRequestsEqual(_r1_, _r2_) is *true*.
As mentioned in HostLoadImportedModule (
@@ -11604,15 +12079,13 @@ InitializeHostDefinedRealm ( ): either a normal completion containing ~unuse
1. Let _realm_ be a new Realm Record.
1. Perform CreateIntrinsics(_realm_).
1. Set _realm_.[[AgentSignifier]] to AgentSignifier().
- 1. Set _realm_.[[GlobalObject]] to *undefined*.
- 1. Set _realm_.[[GlobalEnv]] to *undefined*.
1. Set _realm_.[[TemplateMap]] to a new empty List.
1. Let _newContext_ be a new execution context.
1. Set the Function of _newContext_ to *null*.
1. Set the Realm of _newContext_ to _realm_.
1. Set the ScriptOrModule of _newContext_ to *null*.
1. Push _newContext_ onto the execution context stack; _newContext_ is now the running execution context.
- 1. If the host requires use of an exotic object to serve as _realm_'s global object, then
+ 1. If the host requires use of a specific object to serve as _realm_'s global object, then
1. Let _global_ be such an object created in a host-defined manner.
1. Else,
1. Let _global_ be OrdinaryObjectCreate(_realm_.[[Intrinsics]].[[%Object.prototype%]]).
@@ -11631,15 +12104,15 @@ InitializeHostDefinedRealm ( ): either a normal completion containing ~unuse
CreateIntrinsics (
- _realmRec_: a Realm Record,
+ _realmRecord_: a Realm Record,
): ~unused~
- 1. Set _realmRec_.[[Intrinsics]] to a new Record.
- 1. [declared="steps,name,length,slots,prototype"] Set fields of _realmRec_.[[Intrinsics]] with the values listed in
@@ -11647,17 +12120,17 @@
SetDefaultGlobalBindings (
- _realmRec_: a Realm Record,
+ _realmRecord_: a Realm Record,
): either a normal completion containing ~unused~ or a throw completion
- 1. Let _global_ be _realmRec_.[[GlobalObject]].
+ 1. Let _global_ be _realmRecord_.[[GlobalObject]].
1. For each property of the Global Object specified in clause
@@ -11670,14 +12143,16 @@ Execution Contexts
An execution context contains whatever implementation specific state is necessary to track the execution progress of its associated code. Each execution context has at least the state components listed in
-
-
- Component
-
-
- Purpose
-
-
+
+
+
+ Component
+
+
+ Purpose
+
+
+
code evaluation state
@@ -11717,14 +12192,16 @@ Execution Contexts
ECMAScript code execution contexts have the additional state components listed in
-
-
- Component
-
-
- Purpose
-
-
+
+
+
+ Component
+
+
+ Purpose
+
+
+
LexicalEnvironment
@@ -11755,14 +12232,16 @@ Execution Contexts
Execution contexts representing the evaluation of Generators have the additional state components listed in
-
-
- Component
-
-
- Purpose
-
-
+
+
+
+ Component
+
+
+ Purpose
+
+
+
Generator
@@ -11785,8 +12264,9 @@ GetActiveScriptOrModule ( ): a Script Record, a Module Record, or *null*
1. If the execution context stack is empty, return *null*.
- 1. Let _ec_ be the topmost execution context on the execution context stack whose ScriptOrModule component is not *null*.
- 1. If no such execution context exists, return *null*. Otherwise, return _ec_'s ScriptOrModule.
+ 1. Let _executionContext_ be the topmost execution context on the execution context stack whose ScriptOrModule component is not *null*.
+ 1. If no such execution context exists, return *null*.
+ 1. Return _executionContext_'s ScriptOrModule.
@@ -11794,19 +12274,19 @@ GetActiveScriptOrModule ( ): a Script Record, a Module Record, or *null*
ResolveBinding (
_name_: a String,
- optional _env_: an Environment Record or *undefined*,
+ optional _envRecord_: an Environment Record or *undefined*,
): either a normal completion containing a Reference Record or a throw completion
- description
- - It is used to determine the binding of _name_. _env_ can be used to explicitly provide the Environment Record that is to be searched for the binding.
+ - It is used to determine the binding of _name_. _envRecord_ can be used to explicitly provide the Environment Record that is to be searched for the binding.
- 1. If _env_ is not present or _env_ is *undefined*, then
- 1. Set _env_ to the running execution context's LexicalEnvironment.
- 1. Assert: _env_ is an Environment Record.
+ 1. If _envRecord_ is not present or _envRecord_ is *undefined*, then
+ 1. Set _envRecord_ to the running execution context's LexicalEnvironment.
+ 1. Assert: _envRecord_ is an Environment Record.
1. Let _strict_ be IsStrict(the syntactic production that is being evaluated).
- 1. Return ? GetIdentifierReference(_env_, _name_, _strict_).
+ 1. Return ? GetIdentifierReference(_envRecord_, _name_, _strict_).
The result of ResolveBinding is always a Reference Record whose [[ReferencedName]] field is _name_.
@@ -11820,13 +12300,13 @@ GetThisEnvironment ( ): an Environment Record
- It finds the Environment Record that currently supplies the binding of the keyword `this`.
- 1. Let _env_ be the running execution context's LexicalEnvironment.
+ 1. Let _envRecord_ be the running execution context's LexicalEnvironment.
1. [id="step-getthisenvironment-loop"] Repeat,
- 1. Let _exists_ be _env_.HasThisBinding().
- 1. If _exists_ is *true*, return _env_.
- 1. Let _outer_ be _env_.[[OuterEnv]].
+ 1. Let _exists_ be _envRecord_.HasThisBinding().
+ 1. If _exists_ is *true*, return _envRecord_.
+ 1. Let _outer_ be _envRecord_.[[OuterEnv]].
1. Assert: _outer_ is not *null*.
- 1. Set _env_ to _outer_.
+ 1. Set _envRecord_ to _outer_.
The loop in step
@@ -11840,8 +12320,8 @@ ResolveThisBinding ( ): either a normal completion containing an ECMAScript
- It determines the binding of the keyword `this` using the LexicalEnvironment of the running execution context.
- 1. Let _envRec_ be GetThisEnvironment().
- 1. Return ? _envRec_.GetThisBinding().
+ 1. Let _envRecord_ be GetThisEnvironment().
+ 1. Return ? _envRecord_.GetThisBinding().
@@ -11852,9 +12332,9 @@ GetNewTarget ( ): an Object or *undefined*
- It determines the NewTarget value using the LexicalEnvironment of the running execution context.
- 1. Let _envRec_ be GetThisEnvironment().
- 1. Assert: _envRec_ has a [[NewTarget]] field.
- 1. Return _envRec_.[[NewTarget]].
+ 1. Let _envRecord_ be GetThisEnvironment().
+ 1. Assert: _envRecord_ has a [[NewTarget]] field.
+ 1. Return _envRecord_.[[NewTarget]].
@@ -11869,6 +12349,49 @@ GetGlobalObject ( ): an Object
1. Return _currentRealm_.[[GlobalObject]].
+
+
+
+ RunSuspendedContext (
+ _context_: an execution context,
+ _completionRecord_: a Completion Record,
+ ): either a normal completion containing either an ECMAScript language value or ~unused~, or an abrupt completion
+
+
+ - description
+ - It resumes _context_ (sending it _completionRecord_ as the resumption value), and waits for the result.
+
+
+ 1. Let _callerContext_ be the running execution context.
+ 1. Suspend _callerContext_.
+ 1. Push _context_ onto the execution context stack; _context_ is now the running execution context.
+ 1. Resume the suspended evaluation of _context_ using _completionRecord_ as the result of the operation that suspended it. Let _result_ be the Completion Record returned by the resumed computation.
+ 1. Assert: When we reach this step, _context_ has already been removed from the execution context stack and _callerContext_ is the running execution context again.
+ 1. Return Completion(_result_).
+
+
+
+
+
+ RunCallerContext (
+ _value_: an ECMAScript language value or ~empty~,
+ ): a Completion Record
+
+
+ - description
+ - It resumes the caller context (sending it _value_ as the resumption value), and waits for the result, if any.
+
+
+ 1. Let _genContext_ be the running execution context.
+ 1. Remove _genContext_ from the execution context stack and restore the execution context that is at the top of the execution context stack as the running execution context.
+ 1. Let _callerContext_ be the running execution context.
+ 1. Resume _callerContext_, passing NormalCompletion(_value_).
+ 1. NOTE: The above step transfers control to _callerContext_ and pauses. The only way for it to un-pause and have control proceed to the subsequent steps in this algorithm is for _genContext_ to be resumed again, which might never happen.
+ 1. Assert: _genContext_ is the running execution context.
+ 1. Let _result_ be the Completion Record with which _genContext_ was just resumed.
+ 1. Return Completion(_result_).
+
+
@@ -11880,7 +12403,7 @@ Jobs and Host Operations to Enqueue Jobs
- At some future point in time, when there is no running context in the agent for which the job is scheduled and that agent's execution context stack is empty, the implementation must:
- Perform any host-defined preparation steps.
- - Invoke the Job Abstract Closure.
+ Invoke the Job Abstract Closure.- Perform any host-defined cleanup steps, after which the execution context stack must be empty.
@@ -11896,7 +12419,7 @@ Jobs and Host Operations to Enqueue Jobs
At any particular time, _scriptOrModule_ (a Script Record, a Module Record, or *null*) is the active script or module if all of the following conditions are true:
- GetActiveScriptOrModule() is _scriptOrModule_.
- - If _scriptOrModule_ is a Script Record or Module Record, let _ec_ be the topmost execution context on the execution context stack whose ScriptOrModule component is _scriptOrModule_. The Realm component of _ec_ is _scriptOrModule_.[[Realm]].
+ - If _scriptOrModule_ is a Script Record or Module Record, let _executionContext_ be the topmost execution context on the execution context stack whose ScriptOrModule component is _scriptOrModule_. The Realm component of _executionContext_ is _scriptOrModule_.[[Realm]].
At any particular time, an execution is prepared to evaluate ECMAScript code if all of the following conditions are true:
@@ -11914,24 +12437,26 @@ Jobs and Host Operations to Enqueue Jobs
JobCallback Records
- A JobCallback Record is a Record value used to store a function object and a host-defined value. Function objects that are invoked via a Job enqueued by the host may have additional host-defined context. To propagate the state, Job Abstract Closures should not capture and call function objects directly. Instead, use HostMakeJobCallback and HostCallJobCallback.
+ A JobCallback Record is a Record used to store a function object and a host-defined value. Function objects that are invoked via a Job enqueued by the host may have additional host-defined context. To propagate the state, Job Abstract Closures should not capture and call function objects directly. Instead, use HostMakeJobCallback and HostCallJobCallback.
The WHATWG HTML specification (https://html.spec.whatwg.org/), for example, uses the host-defined value to propagate the incumbent settings object for Promise callbacks.
JobCallback Records have the fields listed in
-
-
- Field Name
-
-
- Value
-
-
- Meaning
-
-
+
+
+
+ Field Name
+
+
+ Value
+
+
+ Meaning
+
+
+
[[Callback]]
@@ -11984,15 +12509,15 @@
HostCallJobCallback (
_jobCallback_: a JobCallback Record,
- _V_: an ECMAScript language value,
- _argumentsList_: a List of ECMAScript language values,
+ _thisValue_: an ECMAScript language value,
+ _argList_: a List of ECMAScript language values,
): either a normal completion containing an ECMAScript language value or a throw completion
An implementation of HostCallJobCallback must conform to the following requirements:
- - It must perform and return the result of Call(_jobCallback_.[[Callback]], _V_, _argumentsList_).
+ - It must perform and return the result of Call(_jobCallback_.[[Callback]], _thisValue_, _argList_).
This requirement means that hosts cannot change the [[Call]] behaviour of function objects defined in this specification.
@@ -12000,7 +12525,7 @@
The default implementation of HostCallJobCallback performs the following steps when called:
1. Assert: IsCallable(_jobCallback_.[[Callback]]) is *true*.
- 1. Return ? Call(_jobCallback_.[[Callback]], _V_, _argumentsList_).
+ 1. Return ? Call(_jobCallback_.[[Callback]], _thisValue_, _argList_).
ECMAScript hosts that are not web browsers must use the default implementation of HostCallJobCallback.
@@ -12071,15 +12596,17 @@ Agents
An agent signifier is a globally-unique opaque value used to identify an Agent.
-
- Field Name
- Value
- Meaning
-
+
+
+ Field Name
+ Value
+ Meaning
+
+
[[LittleEndian]]
a Boolean
- The default value computed for the isLittleEndian parameter when it is needed by the algorithms GetValueFromBuffer and SetValueInBuffer. The choice is implementation-defined and should be the alternative that is most efficient for the implementation. Once the value has been observed it cannot change.
+ The default value computed for the isLittleEndian parameter when it is needed by the algorithms GetValueFromBuffer and SetValueInBuffer. The choice is implementation-defined and should be the alternative that is most efficient for the implementation.
[[CanBlock]]
@@ -12116,13 +12643,25 @@ Agents
a List of either Objects or Symbols
Initially a new empty List, representing the list of objects and/or symbols to be kept alive until the end of the current Job
+
+ [[ModuleAsyncEvaluationCount]]
+ an integer
+ Initially 0, used to assign unique incrementing values to the [[AsyncEvaluationOrder]] field of modules that are asynchronous or have asynchronous dependencies.
+
+
+ [[GlobalSymbolRegistry]]
+ a List of GlobalSymbolRegistry Records
+ Initially a new empty List, representing the list of Symbol values produced by Symbol.for .
+
- Once the values of [[Signifier]], [[IsLockFree1]], and [[IsLockFree2]] have been observed by any agent in the agent cluster they cannot change.
+ The values of [[LittleEndian]], [[Signifier]], [[IsLockFree1]], [[IsLockFree2]], and [[IsLockFree8]] cannot change.
+
+ The [[GlobalSymbolRegistry]] List is append-only and never reassigned.
- The values of [[IsLockFree1]] and [[IsLockFree2]] are not necessarily determined by the hardware, but may also reflect implementation choices that can vary over time and between ECMAScript implementations.
+ The values of [[IsLockFree1]], [[IsLockFree2]], and [[IsLockFree8]] are not necessarily determined by the hardware, but may also reflect implementation choices that can vary over time and between ECMAScript implementations.
There is no [[IsLockFree4]] field: 4-byte atomic operations are always lock-free.
@@ -12140,8 +12679,8 @@ AgentSignifier ( ): an agent signifier
- 1. Let _AR_ be the Agent Record of the surrounding agent.
- 1. Return _AR_.[[Signifier]].
+ 1. Let _agentRecord_ be the Agent Record of the surrounding agent.
+ 1. Return _agentRecord_.[[Signifier]].
@@ -12150,13 +12689,28 @@ AgentCanSuspend ( ): a Boolean
- 1. Let _AR_ be the Agent Record of the surrounding agent.
- 1. Return _AR_.[[CanBlock]].
+ 1. Let _agentRecord_ be the Agent Record of the surrounding agent.
+ 1. Return _agentRecord_.[[CanBlock]].
In some environments it may not be reasonable for a given agent to suspend. For example, in a web browser environment, it may be reasonable to disallow suspending a document's main event handling thread, while still allowing workers' event handling threads to suspend.
+
+
+ IncrementModuleAsyncEvaluationCount ( ): a non-negative integer
+
+
+
+ 1. Let _agentRecord_ be the Agent Record of the surrounding agent.
+ 1. Let _count_ be _agentRecord_.[[ModuleAsyncEvaluationCount]].
+ 1. Set _agentRecord_.[[ModuleAsyncEvaluationCount]] to _count_ + 1.
+ 1. Return _count_.
+
+
+ This value is only used to keep track of the relative evaluation order between pending modules. An implementation may unobservably reset [[ModuleAsyncEvaluationCount]] to 0 whenever there are no pending modules.
+
+
@@ -12182,7 +12736,7 @@ Agent Clusters
If different agents within an agent cluster have different values of [[LittleEndian]] it becomes hard to use shared memory for multi-byte data.
- All agents within a cluster must have the same values for the [[IsLockFree1]] field in their respective Agent Records; similarly for the [[IsLockFree2]] field.
+ All agents within a cluster must have the same values for the [[IsLockFree1]] field in their respective Agent Records; similarly for the [[IsLockFree2]] and [[IsLockFree8]] fields.
All agents within a cluster must have different values for the [[Signifier]] field in their respective Agent Records.
@@ -12241,7 +12795,7 @@ Processing Model of WeakRef and FinalizationRegistry Targets
Objectives
- This specification does not make any guarantees that any object or symbol will be garbage collected. Objects or symbols which are not live may be released after long periods of time, or never at all. For this reason, this specification uses the term "may" when describing behaviour triggered by garbage collection.
+ This specification does not make any guarantees that any object or symbol will be garbage collected. Objects or symbols which are not live may be released after long periods of time, or never at all. For this reason, this specification uses the term “may” when describing behaviour triggered by garbage collection.
The semantics of WeakRefs and FinalizationRegistrys is based on two operations which happen at particular points in time:
@@ -12263,7 +12817,7 @@ Objectives
Liveness
- For some set of objects and/or symbols _S_ a hypothetical WeakRef-oblivious execution with respect to _S_ is an execution whereby the abstract operation WeakRefDeref of a WeakRef whose referent is an element of _S_ always returns *undefined*.
+ For some set of objects and/or symbols _objSet_ a hypothetical WeakRef-oblivious execution with respect to _objSet_ is an execution whereby the abstract operation WeakRefDeref of a WeakRef whose referent is an element of _objSet_ always returns *undefined*.
WeakRef-obliviousness, together with liveness, capture two notions. One, that a WeakRef itself does not keep its referent alive. Two, that cycles in liveness does not imply that a value is live. To be concrete, if determining _v_'s liveness depends on determining the liveness of a WeakRef referent, _r_, _r_'s liveness cannot assume _v_'s liveness, which would be circular reasoning.
@@ -12275,14 +12829,14 @@ Liveness
Colloquially, we say that an individual object or symbol is live if every set containing it is live.
- At any point during evaluation, a set of objects and/or symbols _S_ is considered live if either of the following conditions is met:
+ At any point during evaluation, a set of objects and/or symbols _objSet_ is considered live if either of the following conditions is met:
-
- Any element in _S_ is included in any agent's [[KeptAlive]] List.
+ Any element in _objSet_ is included in any agent's [[KeptAlive]] List.
-
- There exists a valid future hypothetical WeakRef-oblivious execution with respect to _S_ that observes the identity of any value in _S_.
+ There exists a valid future hypothetical WeakRef-oblivious execution with respect to _objSet_ that observes the identity of any value in _objSet_.
@@ -12303,18 +12857,19 @@ Liveness
Execution
- At any time, if a set of objects and/or symbols _S_ is not live, an ECMAScript implementation may perform the following steps atomically:
+ At any time, if a set of objects and/or symbols _objSet_ is not live, an ECMAScript implementation may perform the following steps atomically:
- 1. For each element _value_ of _S_, do
+ 1. For each element _value_ of _objSet_, do
1. For each WeakRef _ref_ such that _ref_.[[WeakRefTarget]] is _value_, do
1. Set _ref_.[[WeakRefTarget]] to ~empty~.
- 1. For each FinalizationRegistry _fg_ such that _fg_.[[Cells]] contains a Record _cell_ such that _cell_.[[WeakRefTarget]] is _value_, do
+ 1. For each FinalizationRegistry _finalizationRegistry_ such that _finalizationRegistry_.[[Cells]] contains a Record _cell_ such that _cell_.[[WeakRefTarget]] is _value_, do
1. Set _cell_.[[WeakRefTarget]] to ~empty~.
- 1. Optionally, perform HostEnqueueFinalizationRegistryCleanupJob(_fg_).
- 1. For each WeakMap _map_ such that _map_.[[WeakMapData]] contains a Record _r_ such that _r_.[[Key]] is _value_, do
- 1. Set _r_.[[Key]] to ~empty~.
- 1. Set _r_.[[Value]] to ~empty~.
+ 1. Let _enqueueCleanup_ be an implementation-defined choice of either *true* or *false*.
+ 1. If _enqueueCleanup_ is *true*, perform HostEnqueueFinalizationRegistryCleanupJob(_finalizationRegistry_).
+ 1. For each WeakMap _map_ such that _map_.[[WeakMapData]] contains a Record _entry_ such that _entry_.[[Key]] is _value_, do
+ 1. Set _entry_.[[Key]] to ~empty~.
+ 1. Set _entry_.[[Value]] to ~empty~.
1. For each WeakSet _set_ such that _set_.[[WeakSetData]] contains _value_, do
1. Replace the element of _set_.[[WeakSetData]] whose value is _value_ with an element whose value is ~empty~.
@@ -12330,7 +12885,7 @@ Execution
Implementations are not obligated to empty WeakRefs for maximal sets of non-live objects or symbols.
- If an implementation chooses a non-live set _S_ in which to empty WeakRefs, this definition requires that it empties WeakRefs for all values in _S_ simultaneously. In other words, it is not conformant for an implementation to empty a WeakRef pointing to a value _v_ without emptying out other WeakRefs that, if not emptied, could result in an execution that observes the value of _v_.
+ If an implementation chooses a non-live set _objSet_ in which to empty WeakRefs, this definition requires that it empties WeakRefs for all values in _objSet_ simultaneously. In other words, it is not conformant for an implementation to empty a WeakRef pointing to a value _v_ without emptying out other WeakRefs that, if not emptied, could result in an execution that observes the value of _v_.
@@ -12409,16 +12964,16 @@
CanBeHeldWeakly (
- _v_: an ECMAScript language value,
+ _arg_: an ECMAScript language value,
): a Boolean
- description
- - It returns *true* if and only if _v_ is suitable for use as a weak reference. Only values that are suitable for use as a weak reference may be a key of a WeakMap, an element of a WeakSet, the target of a WeakRef, or one of the targets of a FinalizationRegistry.
+ - It returns *true* if and only if _arg_ is suitable for use as a weak reference. Only values that are suitable for use as a weak reference may be a key of a WeakMap, an element of a WeakSet, the target of a WeakRef, or one of the targets of a FinalizationRegistry.
- 1. If _v_ is an Object, return *true*.
- 1. If _v_ is a Symbol and KeyForSymbol(_v_) is *undefined*, return *true*.
+ 1. If _arg_ is an Object, return *true*.
+ 1. If _arg_ is a Symbol and KeyForSymbol(_arg_) is *undefined*, return *true*.
1. Return *false*.
@@ -12432,31 +12987,31 @@ Ordinary and Exotic Objects Behaviours
Ordinary Object Internal Methods and Internal Slots
- All ordinary objects have an internal slot called [[Prototype]]. The value of this internal slot is either *null* or an object and is used for implementing inheritance. Assume a property named _P_ is missing from an ordinary object _O_ but exists on its [[Prototype]] object. If _P_ refers to a data property on the [[Prototype]] object, _O_ inherits it for get access, making it behave as if _P_ was a property of _O_. If _P_ refers to a writable data property on the [[Prototype]] object, set access of _P_ on _O_ creates a new data property named _P_ on _O_. If _P_ refers to a non-writable data property on the [[Prototype]] object, set access of _P_ on _O_ fails. If _P_ refers to an accessor property on the [[Prototype]] object, the accessor is inherited by _O_ for both get access and set access.
+ All ordinary objects have an internal slot called [[Prototype]]. The value of this internal slot is either *null* or an object and is used for implementing inheritance. Assume a property named _propertyKey_ is missing from an ordinary object _obj_ but exists on its [[Prototype]] object. If _propertyKey_ refers to a data property on the [[Prototype]] object, _obj_ inherits it for get access, making it behave as if _propertyKey_ was a property of _obj_. If _propertyKey_ refers to a writable data property on the [[Prototype]] object, set access of _propertyKey_ on _obj_ creates a new data property named _propertyKey_ on _obj_. If _propertyKey_ refers to a non-writable data property on the [[Prototype]] object, set access of _propertyKey_ on _obj_ fails. If _propertyKey_ refers to an accessor property on the [[Prototype]] object, the accessor is inherited by _obj_ for both get access and set access.
Every ordinary object has a Boolean-valued [[Extensible]] internal slot which is used to fulfill the extensibility-related internal method invariants specified in
- In the following algorithm descriptions, assume _O_ is an ordinary object, _P_ is a property key value, _V_ is any ECMAScript language value, and _Desc_ is a Property Descriptor record.
- Each ordinary object internal method delegates to a similarly-named abstract operation. If such an abstract operation depends on another internal method, then the internal method is invoked on _O_ rather than calling the similarly-named abstract operation directly. These semantics ensure that exotic objects have their overridden internal methods invoked when ordinary object internal methods are applied to them.
+ In the following algorithm descriptions, assume _obj_ is an ordinary object, _propertyKey_ is a property key value, _value_ is any ECMAScript language value, and _propertyDesc_ is a Property Descriptor record.
+ Each ordinary object internal method delegates to a similarly-named abstract operation. If such an abstract operation depends on another internal method, then the internal method is invoked on _obj_ rather than calling the similarly-named abstract operation directly. These semantics ensure that exotic objects have their overridden internal methods invoked when ordinary object internal methods are applied to them.
[[GetPrototypeOf]] ( ): a normal completion containing either an Object or *null*
- for
- - an ordinary object _O_
+ - an ordinary object _obj_
- 1. Return OrdinaryGetPrototypeOf(_O_).
+ 1. Return OrdinaryGetPrototypeOf(_obj_).
OrdinaryGetPrototypeOf (
- _O_: an Object,
+ _obj_: an Object,
): an Object or *null*
- 1. Return _O_.[[Prototype]].
+ 1. Return _obj_.[[Prototype]].
@@ -12464,46 +13019,46 @@
[[SetPrototypeOf]] (
- _V_: an Object or *null*,
+ _proto_: an Object or *null*,
): a normal completion containing a Boolean
- for
- - an ordinary object _O_
+ - an ordinary object _obj_
- 1. Return OrdinarySetPrototypeOf(_O_, _V_).
+ 1. Return OrdinarySetPrototypeOf(_obj_, _proto_).
OrdinarySetPrototypeOf (
- _O_: an Object,
- _V_: an Object or *null*,
+ _obj_: an Object,
+ _proto_: an Object or *null*,
): a Boolean
- 1. Let _current_ be _O_.[[Prototype]].
- 1. If SameValue(_V_, _current_) is *true*, return *true*.
- 1. Let _extensible_ be _O_.[[Extensible]].
+ 1. Let _current_ be _obj_.[[Prototype]].
+ 1. If SameValue(_proto_, _current_) is *true*, return *true*.
+ 1. Let _extensible_ be _obj_.[[Extensible]].
1. If _extensible_ is *false*, return *false*.
- 1. Let _p_ be _V_.
+ 1. Let _cursor_ be _proto_.
1. Let _done_ be *false*.
1. [id="step-ordinarysetprototypeof-loop"] Repeat, while _done_ is *false*,
- 1. If _p_ is *null*, then
+ 1. If _cursor_ is *null*, then
1. Set _done_ to *true*.
- 1. Else if SameValue(_p_, _O_) is *true*, then
+ 1. Else if SameValue(_cursor_, _obj_) is *true*, then
1. Return *false*.
1. Else,
- 1. If _p_.[[GetPrototypeOf]] is not the ordinary object internal method defined in
- The loop in step
+ The loop in step
@@ -12512,22 +13067,22 @@
[[IsExtensible]] ( ): a normal completion containing a Boolean
- for
- - an ordinary object _O_
+ - an ordinary object _obj_
- 1. Return OrdinaryIsExtensible(_O_).
+ 1. Return OrdinaryIsExtensible(_obj_).
OrdinaryIsExtensible (
- _O_: an Object,
+ _obj_: an Object,
): a Boolean
- 1. Return _O_.[[Extensible]].
+ 1. Return _obj_.[[Extensible]].
@@ -12536,22 +13091,22 @@
[[PreventExtensions]] ( ): a normal completion containing *true*
- for
- - an ordinary object _O_
+ - an ordinary object _obj_
- 1. Return OrdinaryPreventExtensions(_O_).
+ 1. Return OrdinaryPreventExtensions(_obj_).
OrdinaryPreventExtensions (
- _O_: an Object,
+ _obj_: an Object,
): *true*
- 1. Set _O_.[[Extensible]] to *false*.
+ 1. Set _obj_.[[Extensible]] to *false*.
1. Return *true*.
@@ -12560,40 +13115,40 @@
[[GetOwnProperty]] (
- _P_: a property key,
+ _propertyKey_: a property key,
): a normal completion containing either a Property Descriptor or *undefined*
- for
- - an ordinary object _O_
+ - an ordinary object _obj_
- 1. Return OrdinaryGetOwnProperty(_O_, _P_).
+ 1. Return OrdinaryGetOwnProperty(_obj_, _propertyKey_).
OrdinaryGetOwnProperty (
- _O_: an Object,
- _P_: a property key,
+ _obj_: an Object,
+ _propertyKey_: a property key,
): a Property Descriptor or *undefined*
- 1. If _O_ does not have an own property with key _P_, return *undefined*.
- 1. Let _D_ be a newly created Property Descriptor with no fields.
- 1. Let _X_ be _O_'s own property whose key is _P_.
- 1. If _X_ is a data property, then
- 1. Set _D_.[[Value]] to the value of _X_'s [[Value]] attribute.
- 1. Set _D_.[[Writable]] to the value of _X_'s [[Writable]] attribute.
+ 1. If _obj_ does not have an own property with key _propertyKey_, return *undefined*.
+ 1. Let _propertyDesc_ be a newly created Property Descriptor with no fields.
+ 1. Let _ownProperty_ be _obj_'s own property whose key is _propertyKey_.
+ 1. If _ownProperty_ is a data property, then
+ 1. Set _propertyDesc_.[[Value]] to the value of _ownProperty_'s [[Value]] attribute.
+ 1. Set _propertyDesc_.[[Writable]] to the value of _ownProperty_'s [[Writable]] attribute.
1. Else,
- 1. Assert: _X_ is an accessor property.
- 1. Set _D_.[[Get]] to the value of _X_'s [[Get]] attribute.
- 1. Set _D_.[[Set]] to the value of _X_'s [[Set]] attribute.
- 1. Set _D_.[[Enumerable]] to the value of _X_'s [[Enumerable]] attribute.
- 1. Set _D_.[[Configurable]] to the value of _X_'s [[Configurable]] attribute.
- 1. Return _D_.
+ 1. Assert: _ownProperty_ is an accessor property.
+ 1. Set _propertyDesc_.[[Getter]] to the value of _ownProperty_'s [[Getter]] attribute.
+ 1. Set _propertyDesc_.[[Setter]] to the value of _ownProperty_'s [[Setter]] attribute.
+ 1. Set _propertyDesc_.[[Enumerable]] to the value of _ownProperty_'s [[Enumerable]] attribute.
+ 1. Set _propertyDesc_.[[Configurable]] to the value of _ownProperty_'s [[Configurable]] attribute.
+ 1. Return _propertyDesc_.
@@ -12601,97 +13156,98 @@
[[DefineOwnProperty]] (
- _P_: a property key,
- _Desc_: a Property Descriptor,
+ _propertyKey_: a property key,
+ _propertyDesc_: a Property Descriptor,
): either a normal completion containing a Boolean or a throw completion
- for
- - an ordinary object _O_
+ - an ordinary object _obj_
- 1. Return ? OrdinaryDefineOwnProperty(_O_, _P_, _Desc_).
+ 1. Return ? OrdinaryDefineOwnProperty(_obj_, _propertyKey_, _propertyDesc_).
OrdinaryDefineOwnProperty (
- _O_: an Object,
- _P_: a property key,
- _Desc_: a Property Descriptor,
+ _obj_: an Object,
+ _propertyKey_: a property key,
+ _propertyDesc_: a Property Descriptor,
): either a normal completion containing a Boolean or a throw completion
- 1. Let _current_ be ? _O_.[[GetOwnProperty]] (_P_).
- 1. Let _extensible_ be ? IsExtensible(_O_).
- 1. Return ValidateAndApplyPropertyDescriptor(_O_, _P_, _extensible_, _Desc_, _current_).
+ 1. Let _current_ be ? _obj_.[[GetOwnProperty]](_propertyKey_) .
+ 1. Let _extensible_ be ? IsExtensible(_obj_).
+ 1. Return ValidateAndApplyPropertyDescriptor(_obj_, _propertyKey_, _extensible_, _propertyDesc_, _current_).
IsCompatiblePropertyDescriptor (
- _Extensible_: a Boolean,
- _Desc_: a Property Descriptor,
- _Current_: a Property Descriptor or *undefined*,
+ _extensible_: a Boolean,
+ _propertyDesc_: a Property Descriptor,
+ _current_: a Property Descriptor or *undefined*,
): a Boolean
- 1. Return ValidateAndApplyPropertyDescriptor(*undefined*, *""*, _Extensible_, _Desc_, _Current_).
+ 1. Return ValidateAndApplyPropertyDescriptor(*undefined*, *""*, _extensible_, _propertyDesc_, _current_).
ValidateAndApplyPropertyDescriptor (
- _O_: an Object or *undefined*,
- _P_: a property key,
+ _obj_: an Object or *undefined*,
+ _propertyKey_: a property key,
_extensible_: a Boolean,
- _Desc_: a Property Descriptor,
+ _propertyDesc_: a Property Descriptor,
_current_: a Property Descriptor or *undefined*,
): a Boolean
- description
- - It returns *true* if and only if _Desc_ can be applied as the property of an object with specified _extensibility_ and current property _current_ while upholding
invariants . When such application is possible and _O_ is not *undefined*, it is performed for the property named _P_ (which is created if necessary).
+ - It returns *true* if and only if _propertyDesc_ can be applied as the property of an object with specified _extensibility_ and current property _current_ while upholding
invariants . When such application is possible and _obj_ is not *undefined*, it is performed for the property named _propertyKey_ (which is created if necessary).
- 1. Assert: _P_ is a property key.
+ 1. Assert: _propertyKey_ is a property key.
1. If _current_ is *undefined*, then
1. If _extensible_ is *false*, return *false*.
- 1. If _O_ is *undefined*, return *true*.
- 1. If IsAccessorDescriptor(_Desc_) is *true*, then
- 1. Create an own accessor property named _P_ of object _O_ whose [[Get]], [[Set]], [[Enumerable]], and [[Configurable]] attributes are set to the value of the corresponding field in _Desc_ if _Desc_ has that field, or to the attribute's default value otherwise.
+ 1. If _obj_ is *undefined*, return *true*.
+ 1. If IsAccessorDescriptor(_propertyDesc_) is *true*, then
+ 1. Create an own accessor property named _propertyKey_ of object _obj_ whose [[Getter]], [[Setter]], [[Enumerable]], and [[Configurable]] attributes are set to the value of the corresponding field in _propertyDesc_ if _propertyDesc_ has that field, or to the attribute's default value otherwise.
1. Else,
- 1. Create an own data property named _P_ of object _O_ whose [[Value]], [[Writable]], [[Enumerable]], and [[Configurable]] attributes are set to the value of the corresponding field in _Desc_ if _Desc_ has that field, or to the attribute's default value otherwise.
+ 1. Create an own data property named _propertyKey_ of object _obj_ whose [[Value]], [[Writable]], [[Enumerable]], and [[Configurable]] attributes are set to the value of the corresponding field in _propertyDesc_ if _propertyDesc_ has that field, or to the attribute's default value otherwise.
1. Return *true*.
1. Assert: _current_ is a fully populated Property Descriptor.
- 1. If _Desc_ does not have any fields, return *true*.
+ 1. If _propertyDesc_ does not have any fields, return *true*.
1. If _current_.[[Configurable]] is *false*, then
- 1. If _Desc_ has a [[Configurable]] field and _Desc_.[[Configurable]] is *true*, return *false*.
- 1. If _Desc_ has an [[Enumerable]] field and _Desc_.[[Enumerable]] is not _current_.[[Enumerable]], return *false*.
- 1. If IsGenericDescriptor(_Desc_) is *false* and IsAccessorDescriptor(_Desc_) is not IsAccessorDescriptor(_current_), return *false*.
+ 1. If _propertyDesc_ has a [[Configurable]] field and _propertyDesc_.[[Configurable]] is *true*, return *false*.
+ 1. If _propertyDesc_ has an [[Enumerable]] field and _propertyDesc_.[[Enumerable]] is not _current_.[[Enumerable]], return *false*.
+ 1. If IsGenericDescriptor(_propertyDesc_) is *false* and IsAccessorDescriptor(_propertyDesc_) is not IsAccessorDescriptor(_current_), return *false*.
1. If IsAccessorDescriptor(_current_) is *true*, then
- 1. If _Desc_ has a [[Get]] field and SameValue(_Desc_.[[Get]], _current_.[[Get]]) is *false*, return *false*.
- 1. If _Desc_ has a [[Set]] field and SameValue(_Desc_.[[Set]], _current_.[[Set]]) is *false*, return *false*.
+ 1. If _propertyDesc_ has a [[Getter]] field and SameValue(_propertyDesc_.[[Getter]], _current_.[[Getter]]) is *false*, return *false*.
+ 1. If _propertyDesc_ has a [[Setter]] field and SameValue(_propertyDesc_.[[Setter]], _current_.[[Setter]]) is *false*, return *false*.
1. Else if _current_.[[Writable]] is *false*, then
- 1. If _Desc_ has a [[Writable]] field and _Desc_.[[Writable]] is *true*, return *false*.
- 1. If _Desc_ has a [[Value]] field and SameValue(_Desc_.[[Value]], _current_.[[Value]]) is *false*, return *false*.
- 1. If _O_ is not *undefined*, then
- 1. If IsDataDescriptor(_current_) is *true* and IsAccessorDescriptor(_Desc_) is *true*, then
- 1. If _Desc_ has a [[Configurable]] field, let _configurable_ be _Desc_.[[Configurable]]; else let _configurable_ be _current_.[[Configurable]].
- 1. If _Desc_ has a [[Enumerable]] field, let _enumerable_ be _Desc_.[[Enumerable]]; else let _enumerable_ be _current_.[[Enumerable]].
- 1. Replace the property named _P_ of object _O_ with an accessor property whose [[Configurable]] and [[Enumerable]] attributes are set to _configurable_ and _enumerable_, respectively, and whose [[Get]] and [[Set]] attributes are set to the value of the corresponding field in _Desc_ if _Desc_ has that field, or to the attribute's default value otherwise.
- 1. Else if IsAccessorDescriptor(_current_) is *true* and IsDataDescriptor(_Desc_) is *true*, then
- 1. If _Desc_ has a [[Configurable]] field, let _configurable_ be _Desc_.[[Configurable]]; else let _configurable_ be _current_.[[Configurable]].
- 1. If _Desc_ has a [[Enumerable]] field, let _enumerable_ be _Desc_.[[Enumerable]]; else let _enumerable_ be _current_.[[Enumerable]].
- 1. Replace the property named _P_ of object _O_ with a data property whose [[Configurable]] and [[Enumerable]] attributes are set to _configurable_ and _enumerable_, respectively, and whose [[Value]] and [[Writable]] attributes are set to the value of the corresponding field in _Desc_ if _Desc_ has that field, or to the attribute's default value otherwise.
+ 1. If _propertyDesc_ has a [[Writable]] field and _propertyDesc_.[[Writable]] is *true*, return *false*.
+ 1. NOTE: SameValue returns *true* for *NaN* values which may be distinguishable by other means. Returning here ensures that any existing property of _obj_ remains unmodified.
+ 1. If _propertyDesc_ has a [[Value]] field, return SameValue(_propertyDesc_.[[Value]], _current_.[[Value]]).
+ 1. If _obj_ is not *undefined*, then
+ 1. If IsDataDescriptor(_current_) is *true* and IsAccessorDescriptor(_propertyDesc_) is *true*, then
+ 1. If _propertyDesc_ has a [[Configurable]] field, let _configurable_ be _propertyDesc_.[[Configurable]]; else let _configurable_ be _current_.[[Configurable]].
+ 1. If _propertyDesc_ has an [[Enumerable]] field, let _enumerable_ be _propertyDesc_.[[Enumerable]]; else let _enumerable_ be _current_.[[Enumerable]].
+ 1. Replace the property named _propertyKey_ of object _obj_ with an accessor property whose [[Configurable]] and [[Enumerable]] attributes are set to _configurable_ and _enumerable_, respectively, and whose [[Getter]] and [[Setter]] attributes are set to the value of the corresponding field in _propertyDesc_ if _propertyDesc_ has that field, or to the attribute's default value otherwise.
+ 1. Else if IsAccessorDescriptor(_current_) is *true* and IsDataDescriptor(_propertyDesc_) is *true*, then
+ 1. If _propertyDesc_ has a [[Configurable]] field, let _configurable_ be _propertyDesc_.[[Configurable]]; else let _configurable_ be _current_.[[Configurable]].
+ 1. If _propertyDesc_ has an [[Enumerable]] field, let _enumerable_ be _propertyDesc_.[[Enumerable]]; else let _enumerable_ be _current_.[[Enumerable]].
+ 1. Replace the property named _propertyKey_ of object _obj_ with a data property whose [[Configurable]] and [[Enumerable]] attributes are set to _configurable_ and _enumerable_, respectively, and whose [[Value]] and [[Writable]] attributes are set to the value of the corresponding field in _propertyDesc_ if _propertyDesc_ has that field, or to the attribute's default value otherwise.
1. Else,
- 1. For each field of _Desc_, set the corresponding attribute of the property named _P_ of object _O_ to the value of the field.
+ 1. For each field name _fieldName_ of _propertyDesc_, set the attribute named _fieldName_ of the property named _propertyKey_ of object _obj_ to the value of _propertyDesc_'s _fieldName_ field.
1. Return *true*.
@@ -12700,32 +13256,32 @@
[[HasProperty]] (
- _P_: a property key,
+ _propertyKey_: a property key,
): either a normal completion containing a Boolean or a throw completion
- for
- - an ordinary object _O_
+ - an ordinary object _obj_
- 1. Return ? OrdinaryHasProperty(_O_, _P_).
+ 1. Return ? OrdinaryHasProperty(_obj_, _propertyKey_).
OrdinaryHasProperty (
- _O_: an Object,
- _P_: a property key,
+ _obj_: an Object,
+ _propertyKey_: a property key,
): either a normal completion containing a Boolean or a throw completion
- 1. Let _hasOwn_ be ? _O_.[[GetOwnProperty]] (_P_).
+ 1. Let _hasOwn_ be ? _obj_.[[GetOwnProperty]](_propertyKey_) .
1. If _hasOwn_ is not *undefined*, return *true*.
- 1. Let _parent_ be ? _O_.[[GetPrototypeOf]] ().
+ 1. Let _parent_ be ? _obj_.[[GetPrototypeOf]]() .
1. If _parent_ is not *null*, then
- 1. Return ? _parent_.[[HasProperty]] (_P_).
+ 1. Return ? _parent_.[[HasProperty]](_propertyKey_) .
1. Return *false*.
@@ -12734,41 +13290,41 @@
[[Get]] (
- _P_: a property key,
- _Receiver_: an ECMAScript language value,
+ _propertyKey_: a property key,
+ _receiver_: an ECMAScript language value,
): either a normal completion containing an ECMAScript language value or a throw completion
- for
- - an ordinary object _O_
+ - an ordinary object _obj_
- 1. Return ? OrdinaryGet(_O_, _P_, _Receiver_).
+ 1. Return ? OrdinaryGet(_obj_, _propertyKey_, _receiver_).
OrdinaryGet (
- _O_: an Object,
- _P_: a property key,
- _Receiver_: an ECMAScript language value,
+ _obj_: an Object,
+ _propertyKey_: a property key,
+ _receiver_: an ECMAScript language value,
): either a normal completion containing an ECMAScript language value or a throw completion
- 1. Let _desc_ be ? _O_.[[GetOwnProperty]] (_P_).
- 1. If _desc_ is *undefined*, then
- 1. Let _parent_ be ? _O_.[[GetPrototypeOf]] ().
+ 1. Let _propertyDesc_ be ? _obj_.[[GetOwnProperty]](_propertyKey_) .
+ 1. If _propertyDesc_ is *undefined*, then
+ 1. Let _parent_ be ? _obj_.[[GetPrototypeOf]]() .
1. If _parent_ is *null*, return *undefined*.
- 1. Return ? _parent_.[[Get]] (_P_, _Receiver_).
- 1. If IsDataDescriptor(_desc_) is *true*, return _desc_.[[Value]].
- 1. Assert: IsAccessorDescriptor(_desc_) is *true*.
- 1. Let _getter_ be _desc_.[[Get]].
+ 1. Return ? _parent_.[[Get]](_propertyKey_, _receiver_) .
+ 1. If IsDataDescriptor(_propertyDesc_) is *true*, return _propertyDesc_.[[Value]].
+ 1. Assert: IsAccessorDescriptor(_propertyDesc_) is *true*.
+ 1. Let _getter_ be _propertyDesc_.[[Getter]].
1. If _getter_ is *undefined*, return *undefined*.
- 1. Return ? Call(_getter_, _Receiver_).
+ 1. Return ? Call(_getter_, _receiver_).
@@ -12776,44 +13332,44 @@
[[Set]] (
- _P_: a property key,
- _V_: an ECMAScript language value,
- _Receiver_: an ECMAScript language value,
+ _propertyKey_: a property key,
+ _value_: an ECMAScript language value,
+ _receiver_: an ECMAScript language value,
): either a normal completion containing a Boolean or a throw completion
- for
- - an ordinary object _O_
+ - an ordinary object _obj_
- 1. Return ? OrdinarySet(_O_, _P_, _V_, _Receiver_).
+ 1. Return ? OrdinarySet(_obj_, _propertyKey_, _value_, _receiver_).
OrdinarySet (
- _O_: an Object,
- _P_: a property key,
- _V_: an ECMAScript language value,
- _Receiver_: an ECMAScript language value,
+ _obj_: an Object,
+ _propertyKey_: a property key,
+ _value_: an ECMAScript language value,
+ _receiver_: an ECMAScript language value,
): either a normal completion containing a Boolean or a throw completion
- 1. Let _ownDesc_ be ? _O_.[[GetOwnProperty]] (_P_).
- 1. Return ? OrdinarySetWithOwnDescriptor(_O_, _P_, _V_, _Receiver_, _ownDesc_).
+ 1. Let _ownDesc_ be ? _obj_.[[GetOwnProperty]](_propertyKey_) .
+ 1. Return ? OrdinarySetWithOwnDescriptor(_obj_, _propertyKey_, _value_, _receiver_, _ownDesc_).
OrdinarySetWithOwnDescriptor (
- _O_: an Object,
- _P_: a property key,
- _V_: an ECMAScript language value,
- _Receiver_: an ECMAScript language value,
+ _obj_: an Object,
+ _propertyKey_: a property key,
+ _value_: an ECMAScript language value,
+ _receiver_: an ECMAScript language value,
_ownDesc_: a Property Descriptor or *undefined*,
): either a normal completion containing a Boolean or a throw completion
@@ -12822,27 +13378,24 @@
1. If _ownDesc_ is *undefined*, then
- 1. Let _parent_ be ? _O_.[[GetPrototypeOf]] ().
- 1. If _parent_ is not *null*, then
- 1. Return ? _parent_.[[Set]] (_P_, _V_, _Receiver_).
- 1. Else,
- 1. Set _ownDesc_ to the PropertyDescriptor { [[Value]]: *undefined*, [[Writable]]: *true*, [[Enumerable]]: *true*, [[Configurable]]: *true* }.
+ 1. Let _parent_ be ? _obj_.[[GetPrototypeOf]]() .
+ 1. If _parent_ is not *null*, return ? _parent_.[[Set]](_propertyKey_, _value_, _receiver_) .
+ 1. Set _ownDesc_ to the PropertyDescriptor { [[Value]]: *undefined*, [[Writable]]: *true*, [[Enumerable]]: *true*, [[Configurable]]: *true* }.
1. If IsDataDescriptor(_ownDesc_) is *true*, then
1. If _ownDesc_.[[Writable]] is *false*, return *false*.
- 1. If _Receiver_ is not an Object, return *false*.
- 1. Let _existingDescriptor_ be ? _Receiver_.[[GetOwnProperty]] (_P_).
- 1. If _existingDescriptor_ is not *undefined*, then
- 1. If IsAccessorDescriptor(_existingDescriptor_) is *true*, return *false*.
- 1. If _existingDescriptor_.[[Writable]] is *false*, return *false*.
- 1. Let _valueDesc_ be the PropertyDescriptor { [[Value]]: _V_ }.
- 1. Return ? _Receiver_.[[DefineOwnProperty]] (_P_, _valueDesc_).
- 1. Else,
- 1. Assert: _Receiver_ does not currently have a property _P_.
- 1. Return ? CreateDataProperty(_Receiver_, _P_, _V_).
+ 1. If _receiver_ is not an Object, return *false*.
+ 1. Let _existingDesc_ be ? _receiver_.[[GetOwnProperty]](_propertyKey_) .
+ 1. If _existingDesc_ is *undefined*, then
+ 1. Assert: _receiver_ does not currently have a property _propertyKey_.
+ 1. Return ? CreateDataProperty(_receiver_, _propertyKey_, _value_).
+ 1. If IsAccessorDescriptor(_existingDesc_) is *true*, return *false*.
+ 1. If _existingDesc_.[[Writable]] is *false*, return *false*.
+ 1. Let _valueDesc_ be the PropertyDescriptor { [[Value]]: _value_ }.
+ 1. Return ? _receiver_.[[DefineOwnProperty]](_propertyKey_, _valueDesc_) .
1. Assert: IsAccessorDescriptor(_ownDesc_) is *true*.
- 1. Let _setter_ be _ownDesc_.[[Set]].
+ 1. Let _setter_ be _ownDesc_.[[Setter]].
1. If _setter_ is *undefined*, return *false*.
- 1. Perform ? Call(_setter_, _Receiver_, « _V_ »).
+ 1. Perform ? Call(_setter_, _receiver_, « _value_ »).
1. Return *true*.
@@ -12851,31 +13404,31 @@
[[Delete]] (
- _P_: a property key,
+ _propertyKey_: a property key,
): either a normal completion containing a Boolean or a throw completion
- for
- - an ordinary object _O_
+ - an ordinary object _obj_
- 1. Return ? OrdinaryDelete(_O_, _P_).
+ 1. Return ? OrdinaryDelete(_obj_, _propertyKey_).
OrdinaryDelete (
- _O_: an Object,
- _P_: a property key,
+ _obj_: an Object,
+ _propertyKey_: a property key,
): either a normal completion containing a Boolean or a throw completion
- 1. Let _desc_ be ? _O_.[[GetOwnProperty]] (_P_).
- 1. If _desc_ is *undefined*, return *true*.
- 1. If _desc_.[[Configurable]] is *true*, then
- 1. Remove the own property with name _P_ from _O_.
+ 1. Let _propertyDesc_ be ? _obj_.[[GetOwnProperty]](_propertyKey_) .
+ 1. If _propertyDesc_ is *undefined*, return *true*.
+ 1. If _propertyDesc_.[[Configurable]] is *true*, then
+ 1. Remove the own property with name _propertyKey_ from _obj_.
1. Return *true*.
1. Return *false*.
@@ -12886,16 +13439,16 @@
[[OwnPropertyKeys]] ( ): a normal completion containing a List of property keys
- for
- - an ordinary object _O_
+ - an ordinary object _obj_
- 1. Return OrdinaryOwnPropertyKeys(_O_).
+ 1. Return OrdinaryOwnPropertyKeys(_obj_).
OrdinaryOwnPropertyKeys (
- _O_: an Object,
+ _obj_: an Object,
): a List of property keys
@@ -12903,12 +13456,12 @@
1. Let _keys_ be a new empty List.
- 1. For each own property key _P_ of _O_ such that _P_ is an array index, in ascending numeric index order, do
- 1. Append _P_ to _keys_.
- 1. For each own property key _P_ of _O_ such that _P_ is a String and _P_ is not an array index, in ascending chronological order of property creation, do
- 1. Append _P_ to _keys_.
- 1. For each own property key _P_ of _O_ such that _P_ is a Symbol, in ascending chronological order of property creation, do
- 1. Append _P_ to _keys_.
+ 1. For each own property key _propertyKey_ of _obj_ such that _propertyKey_ is an array index, in ascending numeric index order, do
+ 1. Append _propertyKey_ to _keys_.
+ 1. For each own property key _propertyKey_ of _obj_ such that _propertyKey_ is a String and _propertyKey_ is not an array index, in ascending chronological order of property creation, do
+ 1. Append _propertyKey_ to _keys_.
+ 1. For each own property key _propertyKey_ of _obj_ such that _propertyKey_ is a Symbol, in ascending chronological order of property creation, do
+ 1. Append _propertyKey_ to _keys_.
1. Return _keys_.
@@ -12928,9 +13481,9 @@
1. Let _internalSlotsList_ be « [[Prototype]], [[Extensible]] ».
1. If _additionalInternalSlotsList_ is present, set _internalSlotsList_ to the list-concatenation of _internalSlotsList_ and _additionalInternalSlotsList_.
- 1. Let _O_ be MakeBasicObject(_internalSlotsList_).
- 1. Set _O_.[[Prototype]] to _proto_.
- 1. Return _O_.
+ 1. Let _obj_ be MakeBasicObject(_internalSlotsList_).
+ 1. Set _obj_.[[Prototype]] to _proto_.
+ 1. Return _obj_.
@@ -12941,7 +13494,7 @@
OrdinaryCreateFromConstructor (
- _constructor_: a constructor,
+ _ctor_: a function object,
_intrinsicDefaultProto_: a String,
optional _internalSlotsList_: a List of names of internal slots,
): either a normal completion containing an Object or a throw completion
@@ -12952,17 +13505,17 @@
1. Assert: _intrinsicDefaultProto_ is this specification's name of an intrinsic object. The corresponding object must be an intrinsic that is intended to be used as the [[Prototype]] value of an object.
- 1. Let _proto_ be ? GetPrototypeFromConstructor(_constructor_, _intrinsicDefaultProto_).
- 1. If _internalSlotsList_ is present, let _slotsList_ be _internalSlotsList_.
- 1. Else, let _slotsList_ be a new empty List.
- 1. Return OrdinaryObjectCreate(_proto_, _slotsList_).
+ 1. Let _proto_ be ? GetPrototypeFromConstructor(_ctor_, _intrinsicDefaultProto_).
+ 1. If _internalSlotsList_ is present, let _slots_ be _internalSlotsList_.
+ 1. Else, let _slots_ be a new empty List.
+ 1. Return OrdinaryObjectCreate(_proto_, _slots_).
GetPrototypeFromConstructor (
- _constructor_: a function object,
+ _ctor_: a function object,
_intrinsicDefaultProto_: a String,
): either a normal completion containing an Object or a throw completion
@@ -12972,31 +13525,31 @@
1. Assert: _intrinsicDefaultProto_ is this specification's name of an intrinsic object. The corresponding object must be an intrinsic that is intended to be used as the [[Prototype]] value of an object.
- 1. Let _proto_ be ? Get(_constructor_, *"prototype"*).
+ 1. Let _proto_ be ? Get(_ctor_, *"prototype"*).
1. If _proto_ is not an Object, then
- 1. Let _realm_ be ? GetFunctionRealm(_constructor_).
+ 1. Let _realm_ be ? GetFunctionRealm(_ctor_).
1. Set _proto_ to _realm_'s intrinsic object named _intrinsicDefaultProto_.
1. Return _proto_.
- If _constructor_ does not supply a [[Prototype]] value, the default value that is used is obtained from the realm of the _constructor_ function rather than from the running execution context.
+ If _ctor_ does not supply a [[Prototype]] value, the default value that is used is obtained from the realm of the _ctor_ function rather than from the running execution context.
RequireInternalSlot (
- _O_: an ECMAScript language value,
+ _obj_: an ECMAScript language value,
_internalSlot_: an internal slot name,
): either a normal completion containing ~unused~ or a throw completion
- description
- - It throws an exception unless _O_ is an Object and has the given internal slot.
+ - It throws an exception unless _obj_ is an Object and has the given internal slot.
- 1. If _O_ is not an Object, throw a *TypeError* exception.
- 1. If _O_ does not have an _internalSlot_ internal slot, throw a *TypeError* exception.
+ 1. If _obj_ is not an Object, throw a *TypeError* exception.
+ 1. If _obj_ does not have an _internalSlot_ internal slot, throw a *TypeError* exception.
1. Return ~unused~.
@@ -13008,17 +13561,19 @@ ECMAScript Function Objects
In addition to [[Extensible]] and [[Prototype]], ECMAScript function objects also have the internal slots listed in
-
-
- Internal Slot
-
-
- Type
-
-
- Description
-
-
+
+
+
+ Internal Slot
+
+
+ Type
+
+
+ Description
+
+
+
[[Environment]]
@@ -13123,7 +13678,7 @@ ECMAScript Function Objects
[[HomeObject]]
- an Object
+ an Object or *undefined*
If the function uses `super`, this is the object whose [[GetPrototypeOf]] provides the object where `super` property lookups begin.
@@ -13191,29 +13746,29 @@ ECMAScript Function Objects
[[Call]] (
- _thisArgument_: an ECMAScript language value,
- _argumentsList_: a List of ECMAScript language values,
+ _thisArg_: an ECMAScript language value,
+ _argList_: a List of ECMAScript language values,
): either a normal completion containing an ECMAScript language value or a throw completion
- for
- - an ECMAScript function object _F_
+ - an ECMAScript function object _func_
1. Let _callerContext_ be the running execution context.
- 1. Let _calleeContext_ be PrepareForOrdinaryCall(_F_, *undefined*).
+ 1. Let _calleeContext_ be PrepareForOrdinaryCall(_func_, *undefined*).
1. Assert: _calleeContext_ is now the running execution context.
- 1. If _F_.[[IsClassConstructor]] is *true*, then
+ 1. If _func_.[[IsClassConstructor]] is *true*, then
1. Let _error_ be a newly created *TypeError* object.
- 1. NOTE: _error_ is created in _calleeContext_ with _F_'s associated Realm Record.
+ 1. NOTE: _error_ is created in _calleeContext_ with _func_'s associated Realm Record.
1. Remove _calleeContext_ from the execution context stack and restore _callerContext_ as the running execution context.
- 1. Return ThrowCompletion(_error_).
- 1. Perform OrdinaryCallBindThis(_F_, _calleeContext_, _thisArgument_).
- 1. Let _result_ be Completion(OrdinaryCallEvaluateBody(_F_, _argumentsList_)).
+ 1. Throw _error_.
+ 1. Perform OrdinaryCallBindThis(_func_, _calleeContext_, _thisArg_).
+ 1. Let _result_ be Completion(OrdinaryCallEvaluateBody(_func_, _argList_)).
1. [id="step-call-pop-context-stack"] Remove _calleeContext_ from the execution context stack and restore _callerContext_ as the running execution context.
1. If _result_ is a return completion, return _result_.[[Value]].
- 1. ReturnIfAbrupt(_result_).
- 1. Return *undefined*.
+ 1. Assert: _result_ is a throw completion.
+ 1. Return ? _result_.
When _calleeContext_ is removed from the execution context stack in step
@@ -13222,7 +13777,7 @@
PrepareForOrdinaryCall (
- _F_: an ECMAScript function object,
+ _func_: an ECMAScript function object,
_newTarget_: an Object or *undefined*,
): an execution context
@@ -13231,14 +13786,14 @@
1. Let _callerContext_ be the running execution context.
1. Let _calleeContext_ be a new ECMAScript code execution context.
- 1. Set the Function of _calleeContext_ to _F_.
- 1. Let _calleeRealm_ be _F_.[[Realm]].
+ 1. Set the Function of _calleeContext_ to _func_.
+ 1. Let _calleeRealm_ be _func_.[[Realm]].
1. Set the Realm of _calleeContext_ to _calleeRealm_.
- 1. Set the ScriptOrModule of _calleeContext_ to _F_.[[ScriptOrModule]].
- 1. Let _localEnv_ be NewFunctionEnvironment(_F_, _newTarget_).
+ 1. Set the ScriptOrModule of _calleeContext_ to _func_.[[ScriptOrModule]].
+ 1. Let _localEnv_ be NewFunctionEnvironment(_func_, _newTarget_).
1. Set the LexicalEnvironment of _calleeContext_ to _localEnv_.
1. Set the VariableEnvironment of _calleeContext_ to _localEnv_.
- 1. Set the PrivateEnvironment of _calleeContext_ to _F_.[[PrivateEnvironment]].
+ 1. Set the PrivateEnvironment of _calleeContext_ to _func_.[[PrivateEnvironment]].
1. If _callerContext_ is not already suspended, suspend _callerContext_.
1. Push _calleeContext_ onto the execution context stack; _calleeContext_ is now the running execution context.
1. NOTE: Any exception objects produced after this point are associated with _calleeRealm_.
@@ -13249,31 +13804,31 @@
OrdinaryCallBindThis (
- _F_: an ECMAScript function object,
+ _func_: an ECMAScript function object,
_calleeContext_: an execution context,
- _thisArgument_: an ECMAScript language value,
+ _thisArg_: an ECMAScript language value,
): ~unused~
- 1. Let _thisMode_ be _F_.[[ThisMode]].
+ 1. Let _thisMode_ be _func_.[[ThisMode]].
1. If _thisMode_ is ~lexical~, return ~unused~.
- 1. Let _calleeRealm_ be _F_.[[Realm]].
+ 1. Let _calleeRealm_ be _func_.[[Realm]].
1. Let _localEnv_ be the LexicalEnvironment of _calleeContext_.
1. If _thisMode_ is ~strict~, then
- 1. Let _thisValue_ be _thisArgument_.
+ 1. Let _thisValue_ be _thisArg_.
1. Else,
- 1. If _thisArgument_ is either *undefined* or *null*, then
+ 1. If _thisArg_ is either *undefined* or *null*, then
1. Let _globalEnv_ be _calleeRealm_.[[GlobalEnv]].
1. Assert: _globalEnv_ is a Global Environment Record.
1. Let _thisValue_ be _globalEnv_.[[GlobalThisValue]].
1. Else,
- 1. Let _thisValue_ be ! ToObject(_thisArgument_).
+ 1. Let _thisValue_ be ! ToObject(_thisArg_).
1. NOTE: ToObject produces wrapper objects using _calleeRealm_.
1. Assert: _localEnv_ is a Function Environment Record.
1. Assert: The next step never returns an abrupt completion because _localEnv_.[[ThisBindingStatus]] is not ~initialized~.
- 1. Perform ! _localEnv_.BindThisValue(_thisValue_).
+ 1. Perform ! BindThisValue(_localEnv_, _thisValue_).
1. Return ~unused~.
@@ -13281,55 +13836,55 @@
Runtime Semantics: EvaluateBody (
- _functionObject_: an ECMAScript function object,
- _argumentsList_: a List of ECMAScript language values,
- ): either a normal completion containing an ECMAScript language value or an abrupt completion
+ _func_: an ECMAScript function object,
+ _argList_: a List of ECMAScript language values,
+ ): a return completion or a throw completion
FunctionBody : FunctionStatementList
- 1. Return ? EvaluateFunctionBody of |FunctionBody| with arguments _functionObject_ and _argumentsList_.
+ 1. Return ? EvaluateFunctionBody of |FunctionBody| with arguments _func_ and _argList_.
ConciseBody : ExpressionBody
- 1. Return ? EvaluateConciseBody of |ConciseBody| with arguments _functionObject_ and _argumentsList_.
+ 1. Return ? EvaluateConciseBody of |ConciseBody| with arguments _func_ and _argList_.
GeneratorBody : FunctionBody
- 1. Return ? EvaluateGeneratorBody of |GeneratorBody| with arguments _functionObject_ and _argumentsList_.
+ 1. Return ? EvaluateGeneratorBody of |GeneratorBody| with arguments _func_ and _argList_.
AsyncGeneratorBody : FunctionBody
- 1. Return ? EvaluateAsyncGeneratorBody of |AsyncGeneratorBody| with arguments _functionObject_ and _argumentsList_.
+ 1. Return ? EvaluateAsyncGeneratorBody of |AsyncGeneratorBody| with arguments _func_ and _argList_.
AsyncFunctionBody : FunctionBody
- 1. Return ? EvaluateAsyncFunctionBody of |AsyncFunctionBody| with arguments _functionObject_ and _argumentsList_.
+ 1. Return ? EvaluateAsyncFunctionBody of |AsyncFunctionBody| with arguments _func_ and _argList_.
AsyncConciseBody : ExpressionBody
- 1. Return ? EvaluateAsyncConciseBody of |AsyncConciseBody| with arguments _functionObject_ and _argumentsList_.
+ 1. Return ? EvaluateAsyncConciseBody of |AsyncConciseBody| with arguments _func_ and _argList_.
Initializer :
`=` AssignmentExpression
- 1. Assert: _argumentsList_ is empty.
- 1. Assert: _functionObject_.[[ClassFieldInitializerName]] is not ~empty~.
+ 1. Assert: _argList_ is empty.
+ 1. Assert: _func_.[[ClassFieldInitializerName]] is not ~empty~.
1. If IsAnonymousFunctionDefinition(|AssignmentExpression|) is *true*, then
- 1. Let _value_ be ? NamedEvaluation of |Initializer| with argument _functionObject_.[[ClassFieldInitializerName]].
+ 1. Let _value_ be ? NamedEvaluation of |Initializer| with argument _func_.[[ClassFieldInitializerName]].
1. Else,
1. Let _rhs_ be ? Evaluation of |AssignmentExpression|.
1. Let _value_ be ? GetValue(_rhs_).
- 1. Return Completion Record { [[Type]]: ~return~, [[Value]]: _value_, [[Target]]: ~empty~ }.
+ 1. Return ReturnCompletion(_value_).
Even though field initializers constitute a function boundary, calling FunctionDeclarationInstantiation does not have any observable effect and so is omitted.
@@ -13338,22 +13893,22 @@
ClassStaticBlockBody : ClassStaticBlockStatementList
- 1. Assert: _argumentsList_ is empty.
- 1. Return ? EvaluateClassStaticBlockBody of |ClassStaticBlockBody| with argument _functionObject_.
+ 1. Assert: _argList_ is empty.
+ 1. Return ? EvaluateClassStaticBlockBody of |ClassStaticBlockBody| with argument _func_.
OrdinaryCallEvaluateBody (
- _F_: an ECMAScript function object,
- _argumentsList_: a List of ECMAScript language values,
- ): either a normal completion containing an ECMAScript language value or an abrupt completion
+ _func_: an ECMAScript function object,
+ _argList_: a List of ECMAScript language values,
+ ): a return completion or a throw completion
- 1. Return ? EvaluateBody of _F_.[[ECMAScriptCode]] with arguments _F_ and _argumentsList_.
+ 1. Return ? EvaluateBody of _func_.[[ECMAScriptCode]] with arguments _func_ and _argList_.
@@ -13361,37 +13916,37 @@
[[Construct]] (
- _argumentsList_: a List of ECMAScript language values,
+ _argList_: a List of ECMAScript language values,
_newTarget_: a constructor,
): either a normal completion containing an Object or a throw completion
- for
- - an ECMAScript function object _F_
+ - an ECMAScript function object _func_
1. Let _callerContext_ be the running execution context.
- 1. Let _kind_ be _F_.[[ConstructorKind]].
+ 1. Let _kind_ be _func_.[[ConstructorKind]].
1. If _kind_ is ~base~, then
- 1. Let _thisArgument_ be ? OrdinaryCreateFromConstructor(_newTarget_, *"%Object.prototype%"*).
- 1. Let _calleeContext_ be PrepareForOrdinaryCall(_F_, _newTarget_).
+ 1. Let _thisArg_ be ? OrdinaryCreateFromConstructor(_newTarget_, *"%Object.prototype%"*).
+ 1. Let _calleeContext_ be PrepareForOrdinaryCall(_func_, _newTarget_).
1. Assert: _calleeContext_ is now the running execution context.
1. If _kind_ is ~base~, then
- 1. Perform OrdinaryCallBindThis(_F_, _calleeContext_, _thisArgument_).
- 1. Let _initializeResult_ be Completion(InitializeInstanceElements(_thisArgument_, _F_)).
+ 1. Perform OrdinaryCallBindThis(_func_, _calleeContext_, _thisArg_).
+ 1. Let _initializeResult_ be Completion(InitializeInstanceElements(_thisArg_, _func_)).
1. If _initializeResult_ is an abrupt completion, then
1. Remove _calleeContext_ from the execution context stack and restore _callerContext_ as the running execution context.
1. Return ? _initializeResult_.
- 1. Let _constructorEnv_ be the LexicalEnvironment of _calleeContext_.
- 1. Let _result_ be Completion(OrdinaryCallEvaluateBody(_F_, _argumentsList_)).
+ 1. Let _ctorEnv_ be the LexicalEnvironment of _calleeContext_.
+ 1. Let _result_ be Completion(OrdinaryCallEvaluateBody(_func_, _argList_)).
1. Remove _calleeContext_ from the execution context stack and restore _callerContext_ as the running execution context.
- 1. If _result_ is a return completion, then
- 1. If _result_.[[Value]] is an Object, return _result_.[[Value]].
- 1. If _kind_ is ~base~, return _thisArgument_.
- 1. If _result_.[[Value]] is not *undefined*, throw a *TypeError* exception.
- 1. Else,
- 1. ReturnIfAbrupt(_result_).
- 1. Let _thisBinding_ be ? _constructorEnv_.GetThisBinding().
+ 1. If _result_ is a throw completion, then
+ 1. Return ? _result_.
+ 1. Assert: _result_ is a return completion.
+ 1. If _result_.[[Value]] is an Object, return _result_.[[Value]].
+ 1. If _kind_ is ~base~, return _thisArg_.
+ 1. If _result_.[[Value]] is not *undefined*, throw a *TypeError* exception.
+ 1. Let _thisBinding_ be ? _ctorEnv_.GetThisBinding().
1. Assert: _thisBinding_ is an Object.
1. Return _thisBinding_.
@@ -13400,12 +13955,12 @@
OrdinaryFunctionCreate (
- _functionPrototype_: an Object,
+ _proto_: an Object,
_sourceText_: a sequence of Unicode code points,
- _ParameterList_: a Parse Node,
- _Body_: a Parse Node,
+ _paramList_: a Parse Node,
+ _body_: a Parse Node,
_thisMode_: ~lexical-this~ or ~non-lexical-this~,
- _env_: an Environment Record,
+ _envRecord_: an Environment Record,
_privateEnv_: a PrivateEnvironment Record or *null*,
): an ECMAScript function object
@@ -13415,35 +13970,35 @@
1. Let _internalSlotsList_ be the internal slots listed in
AddRestrictedFunctionProperties (
- _F_: a function object,
+ _func_: a function object,
_realm_: a Realm Record,
): ~unused~
@@ -13452,12 +14007,12 @@
1. Assert: _realm_.[[Intrinsics]].[[%ThrowTypeError%]] exists and has been initialized.
1. Let _thrower_ be _realm_.[[Intrinsics]].[[%ThrowTypeError%]].
- 1. Perform ! DefinePropertyOrThrow(_F_, *"caller"*, PropertyDescriptor { [[Get]]: _thrower_, [[Set]]: _thrower_, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
- 1. Perform ! DefinePropertyOrThrow(_F_, *"arguments"*, PropertyDescriptor { [[Get]]: _thrower_, [[Set]]: _thrower_, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
+ 1. Perform ! DefinePropertyOrThrow(_func_, *"caller"*, PropertyDescriptor { [[Getter]]: _thrower_, [[Setter]]: _thrower_, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
+ 1. Perform ! DefinePropertyOrThrow(_func_, *"arguments"*, PropertyDescriptor { [[Getter]]: _thrower_, [[Setter]]: _thrower_, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
1. Return ~unused~.
-
+
%ThrowTypeError% ( )
This function is the %ThrowTypeError% intrinsic object.
It is an anonymous built-in function object that is defined once for each realm.
@@ -13474,28 +14029,28 @@ %ThrowTypeError% ( )
MakeConstructor (
- _F_: an ECMAScript function object or a built-in function object,
- optional _writablePrototype_: a Boolean,
- optional _prototype_: an Object,
+ _func_: an ECMAScript function object or a built-in function object,
+ optional _writableProto_: a Boolean,
+ optional _proto_: an Object,
): ~unused~
- description
- - It converts _F_ into a constructor.
+ - It converts _func_ into a constructor.
- 1. If _F_ is an ECMAScript function object, then
- 1. Assert: IsConstructor(_F_) is *false*.
- 1. Assert: _F_ is an extensible object that does not have a *"prototype"* own property.
- 1. Set _F_.[[Construct]] to the definition specified in
@@ -13503,14 +14058,14 @@
MakeClassConstructor (
- _F_: an ECMAScript function object,
+ _func_: an ECMAScript function object,
): ~unused~
- 1. Assert: _F_.[[IsClassConstructor]] is *false*.
- 1. Set _F_.[[IsClassConstructor]] to *true*.
+ 1. Assert: _func_.[[IsClassConstructor]] is *false*.
+ 1. Set _func_.[[IsClassConstructor]] to *true*.
1. Return ~unused~.
@@ -13518,16 +14073,17 @@
MakeMethod (
- _F_: an ECMAScript function object,
- _homeObject_: an Object,
+ _func_: an ECMAScript function object,
+ _homeObj_: an Object,
): ~unused~
- description
- - It configures _F_ as a method.
+ - It configures _func_ as a method.
- 1. Set _F_.[[HomeObject]] to _homeObject_.
+ 1. Assert: _homeObj_ is an ordinary object.
+ 1. Set _func_.[[HomeObject]] to _homeObj_.
1. Return ~unused~.
@@ -13535,8 +14091,8 @@
DefineMethodProperty (
- _homeObject_: an Object,
- _key_: a property key or Private Name,
+ _homeObj_: an Object,
+ _name_: a property key or Private Name,
_closure_: a function object,
_enumerable_: a Boolean,
): either a normal completion containing either a PrivateElement or ~unused~, or an abrupt completion
@@ -13544,44 +14100,44 @@
- 1. Assert: _homeObject_ is an ordinary, extensible object.
- 1. If _key_ is a Private Name, then
- 1. Return PrivateElement { [[Key]]: _key_, [[Kind]]: ~method~, [[Value]]: _closure_ }.
- 1. Else,
- 1. Let _desc_ be the PropertyDescriptor { [[Value]]: _closure_, [[Writable]]: *true*, [[Enumerable]]: _enumerable_, [[Configurable]]: *true* }.
- 1. Perform ? DefinePropertyOrThrow(_homeObject_, _key_, _desc_).
- 1. NOTE: DefinePropertyOrThrow only returns an abrupt completion when attempting to define a class static method whose _key_ is *"prototype"*.
- 1. Return ~unused~.
+ 1. Assert: _homeObj_ is an ordinary, extensible object.
+ 1. If _name_ is a Private Name, return PrivateElement { [[Key]]: _name_, [[Kind]]: ~method~, [[Value]]: _closure_ }.
+ 1. Let _propertyDesc_ be the PropertyDescriptor { [[Value]]: _closure_, [[Writable]]: *true*, [[Enumerable]]: _enumerable_, [[Configurable]]: *true* }.
+ 1. Perform ? DefinePropertyOrThrow(_homeObj_, _name_, _propertyDesc_).
+ 1. NOTE: DefinePropertyOrThrow only returns an abrupt completion when attempting to define a class static method whose _name_ is *"prototype"*.
+ 1. Return ~unused~.
SetFunctionName (
- _F_: a function object,
+ _func_: a function object,
_name_: a property key or Private Name,
optional _prefix_: a String,
): ~unused~
- description
- - It adds a *"name"* property to _F_.
+ - It adds a *"name"* property to _func_.
- 1. Assert: _F_ is an extensible object that does not have a *"name"* own property.
+ 1. Assert: _func_ is an extensible object that does not have a *"name"* own property.
1. If _name_ is a Symbol, then
- 1. Let _description_ be _name_'s [[Description]] value.
+ 1. Let _description_ be _name_.[[Description]].
1. If _description_ is *undefined*, set _name_ to the empty String.
1. Else, set _name_ to the string-concatenation of *"["*, _description_, and *"]"*.
1. Else if _name_ is a Private Name, then
1. Set _name_ to _name_.[[Description]].
- 1. If _F_ has an [[InitialName]] internal slot, then
- 1. Set _F_.[[InitialName]] to _name_.
+ 1. If _func_ has an [[InitialName]] internal slot, then
+ 1. Set _func_.[[InitialName]] to _name_.
1. If _prefix_ is present, then
- 1. Set _name_ to the string-concatenation of _prefix_, the code unit 0x0020 (SPACE), and _name_.
- 1. If _F_ has an [[InitialName]] internal slot, then
- 1. Optionally, set _F_.[[InitialName]] to _name_.
- 1. Perform ! DefinePropertyOrThrow(_F_, *"name"*, PropertyDescriptor { [[Value]]: _name_, [[Writable]]: *false*, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
+ 1. Let _prefixedName_ be the string-concatenation of _prefix_, the code unit 0x0020 (SPACE), and _name_.
+ 1. If _func_ has an [[InitialName]] internal slot, then
+ 1. NOTE: The choice in the following step is made independently each time this Abstract Operation is invoked.
+ 1. Set _func_.[[InitialName]] to an implementation-defined choice of either _name_ or _prefixedName_.
+ 1. Set _name_ to _prefixedName_.
+ 1. Perform ! DefinePropertyOrThrow(_func_, *"name"*, PropertyDescriptor { [[Value]]: _name_, [[Writable]]: *false*, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
1. Return ~unused~.
@@ -13589,27 +14145,27 @@
SetFunctionLength (
- _F_: a function object,
+ _func_: a function object,
_length_: a non-negative integer or +∞,
): ~unused~
- description
- - It adds a *"length"* property to _F_.
+ - It adds a *"length"* property to _func_.
- 1. Assert: _F_ is an extensible object that does not have a *"length"* own property.
- 1. Perform ! DefinePropertyOrThrow(_F_, *"length"*, PropertyDescriptor { [[Value]]: 𝔽(_length_), [[Writable]]: *false*, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
+ 1. Assert: _func_ is an extensible object that does not have a *"length"* own property.
+ 1. Perform ! DefinePropertyOrThrow(_func_, *"length"*, PropertyDescriptor { [[Value]]: 𝔽(_length_), [[Writable]]: *false*, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
1. Return ~unused~.
-
+
FunctionDeclarationInstantiation (
_func_: an ECMAScript function object,
- _argumentsList_: a List of ECMAScript language values,
- ): either a normal completion containing ~unused~ or an abrupt completion
+ _argList_: a List of ECMAScript language values,
+ ): either a normal completion containing ~unused~ or a throw completion
- description
@@ -13619,127 +14175,135 @@
When an execution context is established for evaluating an ECMAScript function a new Function Environment Record is created and bindings for each formal parameter are instantiated in that Environment Record. Each declaration in the function body is also instantiated. If the function's formal parameters do not include any default value initializers then the body declarations are instantiated in the same Environment Record as the parameters. If default value parameter initializers exist, a second Environment Record is created for the body declarations. Formal parameters and functions are initialized as part of FunctionDeclarationInstantiation. All other bindings are initialized during evaluation of the function body.
It performs the following steps when called:
-
1. Let _calleeContext_ be the running execution context.
1. Let _code_ be _func_.[[ECMAScriptCode]].
1. Let _strict_ be _func_.[[Strict]].
1. Let _formals_ be _func_.[[FormalParameters]].
- 1. Let _parameterNames_ be the BoundNames of _formals_.
- 1. If _parameterNames_ has any duplicate entries, let _hasDuplicates_ be *true*. Otherwise, let _hasDuplicates_ be *false*.
- 1. Let _simpleParameterList_ be IsSimpleParameterList of _formals_.
- 1. Let _hasParameterExpressions_ be ContainsExpression of _formals_.
- 1. Let _varNames_ be the VarDeclaredNames of _code_.
- 1. Let _varDeclarations_ be the VarScopedDeclarations of _code_.
+ 1. Let _paramNames_ be the BoundNames of _formals_.
+ 1. If _paramNames_ has any duplicate entries, let _hasDuplicates_ be *true*; else let _hasDuplicates_ be *false*.
+ 1. Let _simpleParamList_ be IsSimpleParameterList of _formals_.
+ 1. Let _hasParamExprs_ be ContainsExpression of _formals_.
+ 1. Let _variableNames_ be the VarDeclaredNames of _code_.
+ 1. Let _variableDecls_ be the VarScopedDeclarations of _code_.
1. Let _lexicalNames_ be the LexicallyDeclaredNames of _code_.
- 1. Let _functionNames_ be a new empty List.
- 1. Let _functionsToInitialize_ be a new empty List.
- 1. For each element _d_ of _varDeclarations_, in reverse List order, do
- 1. If _d_ is neither a |VariableDeclaration| nor a |ForBinding| nor a |BindingIdentifier|, then
- 1. Assert: _d_ is either a |FunctionDeclaration|, a |GeneratorDeclaration|, an |AsyncFunctionDeclaration|, or an |AsyncGeneratorDeclaration|.
- 1. Let _fn_ be the sole element of the BoundNames of _d_.
- 1. If _functionNames_ does not contain _fn_, then
- 1. Insert _fn_ as the first element of _functionNames_.
+ 1. Let _funcNames_ be a new empty List.
+ 1. Let _funcsToInitialize_ be a new empty List.
+ 1. For each element _variableDecl_ of _variableDecls_, in reverse List order, do
+ 1. If _variableDecl_ is neither a |VariableDeclaration| nor a |ForBinding| nor a |BindingIdentifier|, then
+ 1. Assert: _variableDecl_ is either a |FunctionDeclaration|, a |GeneratorDeclaration|, an |AsyncFunctionDeclaration|, or an |AsyncGeneratorDeclaration|.
+ 1. Let _funcName_ be the sole element of the BoundNames of _variableDecl_.
+ 1. If _funcNames_ does not contain _funcName_, then
+ 1. Insert _funcName_ as the first element of _funcNames_.
1. NOTE: If there are multiple function declarations for the same name, the last declaration is used.
- 1. Insert _d_ as the first element of _functionsToInitialize_.
- 1. Let _argumentsObjectNeeded_ be *true*.
+ 1. Insert _variableDecl_ as the first element of _funcsToInitialize_.
+ 1. Let _argumentsObjNeeded_ be *true*.
1. If _func_.[[ThisMode]] is ~lexical~, then
1. NOTE: Arrow functions never have an arguments object.
- 1. Set _argumentsObjectNeeded_ to *false*.
- 1. Else if _parameterNames_ contains *"arguments"*, then
- 1. Set _argumentsObjectNeeded_ to *false*.
- 1. Else if _hasParameterExpressions_ is *false*, then
- 1. If _functionNames_ contains *"arguments"* or _lexicalNames_ contains *"arguments"*, then
- 1. Set _argumentsObjectNeeded_ to *false*.
- 1. If _strict_ is *true* or _hasParameterExpressions_ is *false*, then
+ 1. Set _argumentsObjNeeded_ to *false*.
+ 1. Else if _paramNames_ contains *"arguments"*, then
+ 1. Set _argumentsObjNeeded_ to *false*.
+ 1. Else if _hasParamExprs_ is *false*, then
+ 1. If _funcNames_ contains *"arguments"* or _lexicalNames_ contains *"arguments"*, then
+ 1. Set _argumentsObjNeeded_ to *false*.
+ 1. If _strict_ is *true* or _hasParamExprs_ is *false*, then
1. NOTE: Only a single Environment Record is needed for the parameters, since calls to `eval` in strict mode code cannot create new bindings which are visible outside of the `eval`.
- 1. Let _env_ be the LexicalEnvironment of _calleeContext_.
+ 1. Let _envRecord_ be the LexicalEnvironment of _calleeContext_.
1. Else,
1. NOTE: A separate Environment Record is needed to ensure that bindings created by direct eval calls in the formal parameter list are outside the environment where parameters are declared.
1. Let _calleeEnv_ be the LexicalEnvironment of _calleeContext_.
- 1. Let _env_ be NewDeclarativeEnvironment(_calleeEnv_).
+ 1. Let _envRecord_ be NewDeclarativeEnvironment(_calleeEnv_).
1. Assert: The VariableEnvironment of _calleeContext_ and _calleeEnv_ are the same Environment Record.
- 1. Set the LexicalEnvironment of _calleeContext_ to _env_.
- 1. For each String _paramName_ of _parameterNames_, do
- 1. Let _alreadyDeclared_ be ! _env_.HasBinding(_paramName_).
+ 1. Set the LexicalEnvironment of _calleeContext_ to _envRecord_.
+ 1. For each String _paramName_ of _paramNames_, do
+ 1. Let _alreadyDeclared_ be ! _envRecord_.HasBinding(_paramName_).
1. NOTE: Early errors ensure that duplicate parameter names can only occur in non-strict functions that do not have parameter default values or rest parameters.
1. If _alreadyDeclared_ is *false*, then
- 1. Perform ! _env_.CreateMutableBinding(_paramName_, *false*).
+ 1. Perform ! _envRecord_.CreateMutableBinding(_paramName_, *false*).
1. If _hasDuplicates_ is *true*, then
- 1. Perform ! _env_.InitializeBinding(_paramName_, *undefined*).
- 1. If _argumentsObjectNeeded_ is *true*, then
- 1. If _strict_ is *true* or _simpleParameterList_ is *false*, then
- 1. Let _ao_ be CreateUnmappedArgumentsObject(_argumentsList_).
+ 1. Perform ! _envRecord_.InitializeBinding(_paramName_, *undefined*).
+ 1. If _argumentsObjNeeded_ is *true*, then
+ 1. If _strict_ is *true* or _simpleParamList_ is *false*, then
+ 1. Let _argumentsObj_ be CreateUnmappedArgumentsObject(_argList_).
1. Else,
1. NOTE: A mapped argument object is only provided for non-strict functions that don't have a rest parameter, any parameter default value initializers, or any destructured parameters.
- 1. Let _ao_ be CreateMappedArgumentsObject(_func_, _formals_, _argumentsList_, _env_).
+ 1. Let _argumentsObj_ be CreateMappedArgumentsObject(_func_, _formals_, _argList_, _envRecord_).
1. If _strict_ is *true*, then
- 1. Perform ! _env_.CreateImmutableBinding(*"arguments"*, *false*).
+ 1. Perform ! _envRecord_.CreateImmutableBinding(*"arguments"*, *false*).
1. NOTE: In strict mode code early errors prevent attempting to assign to this binding, so its mutability is not observable.
1. Else,
- 1. Perform ! _env_.CreateMutableBinding(*"arguments"*, *false*).
- 1. Perform ! _env_.InitializeBinding(*"arguments"*, _ao_).
- 1. Let _parameterBindings_ be the list-concatenation of _parameterNames_ and « *"arguments"* ».
+ 1. Perform ! _envRecord_.CreateMutableBinding(*"arguments"*, *false*).
+ 1. Perform ! _envRecord_.InitializeBinding(*"arguments"*, _argumentsObj_).
+ 1. Let _paramBindings_ be the list-concatenation of _paramNames_ and « *"arguments"* ».
1. Else,
- 1. Let _parameterBindings_ be _parameterNames_.
- 1. Let _iteratorRecord_ be CreateListIteratorRecord(_argumentsList_).
+ 1. Let _paramBindings_ be _paramNames_.
+ 1. Let _iteratorRecord_ be CreateListIteratorRecord(_argList_).
1. If _hasDuplicates_ is *true*, then
- 1. Perform ? IteratorBindingInitialization of _formals_ with arguments _iteratorRecord_ and *undefined*.
+ 1. Let _usedEnv_ be *undefined*.
1. Else,
- 1. Perform ? IteratorBindingInitialization of _formals_ with arguments _iteratorRecord_ and _env_.
- 1. If _hasParameterExpressions_ is *false*, then
+ 1. Let _usedEnv_ be _envRecord_.
+ 1. NOTE: The following step cannot return a ReturnCompletion because the only way such a completion can arise in expression position is by use of |YieldExpression|, which is forbidden in parameter lists by Early Error rules in
-
-
-
@@ -13750,6 +14314,7 @@ Built-in Function Objects
- [[Realm]], a Realm Record that represents the realm in which the function was created.
- [[InitialName]], a String that is the initial name of the function. It is used by
+ - [[Async]], a Boolean that indicates whether the function has async function call and construct behaviour in BuiltinCallOrConstruct.
The initial value of a built-in function object's [[Prototype]] internal slot is %Function.prototype%, unless otherwise specified.
A built-in function object must have a [[Call]] internal method that conforms to the definition in
@@ -13759,41 +14324,43 @@ Built-in Function Objects
[[Call]] (
- _thisArgument_: an ECMAScript language value,
- _argumentsList_: a List of ECMAScript language values,
+ _thisArg_: an ECMAScript language value,
+ _argList_: a List of ECMAScript language values,
): either a normal completion containing an ECMAScript language value or a throw completion
- for
- - a built-in function object _F_
+ - a built-in function object _func_
- 1. Return ? BuiltinCallOrConstruct(_F_, _thisArgument_, _argumentsList_, *undefined*).
+ 1. Return ? BuiltinCallOrConstruct(_func_, _thisArg_, _argList_, *undefined*).
[[Construct]] (
- _argumentsList_: a List of ECMAScript language values,
+ _argList_: a List of ECMAScript language values,
_newTarget_: a constructor,
): either a normal completion containing an Object or a throw completion
- for
- - a built-in function object _F_ (when the method is present)
+ - a built-in function object _func_ (when the method is present)
- 1. Return ? BuiltinCallOrConstruct(_F_, ~uninitialized~, _argumentsList_, _newTarget_).
+ 1. Let _result_ be ? BuiltinCallOrConstruct(_func_, ~uninitialized~, _argList_, _newTarget_).
+ 1. Assert: _result_ is an Object.
+ 1. Return _result_.
BuiltinCallOrConstruct (
- _F_: a built-in function object,
- _thisArgument_: an ECMAScript language value or ~uninitialized~,
- _argumentsList_: a List of ECMAScript language values,
+ _func_: a built-in function object,
+ _thisArg_: an ECMAScript language value or ~uninitialized~,
+ _argList_: a List of ECMAScript language values,
_newTarget_: a constructor or *undefined*,
): either a normal completion containing an ECMAScript language value or a throw completion
@@ -13803,14 +14370,23 @@
1. Let _callerContext_ be the running execution context.
1. If _callerContext_ is not already suspended, suspend _callerContext_.
1. Let _calleeContext_ be a new execution context.
- 1. Set the Function of _calleeContext_ to _F_.
- 1. Let _calleeRealm_ be _F_.[[Realm]].
+ 1. Set the Function of _calleeContext_ to _func_.
+ 1. Let _calleeRealm_ be _func_.[[Realm]].
1. Set the Realm of _calleeContext_ to _calleeRealm_.
1. Set the ScriptOrModule of _calleeContext_ to *null*.
1. Perform any necessary implementation-defined initialization of _calleeContext_.
1. Push _calleeContext_ onto the execution context stack; _calleeContext_ is now the running execution context.
- 1. [id="step-call-builtin-function-result"] Let _result_ be the Completion Record that is the result of evaluating _F_ in a manner that conforms to the specification of _F_. If _thisArgument_ is ~uninitialized~, the *this* value is uninitialized; otherwise, _thisArgument_ provides the *this* value. _argumentsList_ provides the named parameters. _newTarget_ provides the NewTarget value.
- 1. NOTE: If _F_ is defined in this document, “the specification of _F_” is the behaviour specified for it via algorithm steps or other means.
+ 1. If _func_.[[Async]] is *true*, then
+ 1. Let _promiseCapability_ be ! NewPromiseCapability(%Promise%).
+ 1. Let _resultsClosure_ be a new Abstract Closure with no parameters that captures _func_, _thisArg_, _argList_, and _newTarget_ and performs the following steps when called:
+ 1. Let _result_ be the Completion Record that is the result of evaluating _func_ in a manner that conforms to the specification of _func_. If _thisArg_ is ~uninitialized~, the *this* value is uninitialized; else _thisArg_ provides the *this* value. _argList_ provides the named parameters. _newTarget_ provides the NewTarget value.
+ 1. NOTE: If _func_ is defined in this document, “the specification of _func_” is the behaviour specified for it via algorithm steps or other means.
+ 1. Return Completion(_result_).
+ 1. Perform AsyncFunctionStart(_promiseCapability_, _resultsClosure_).
+ 1. Remove _calleeContext_ from the execution context stack and restore _callerContext_ as the running execution context.
+ 1. Return _promiseCapability_.[[Promise]].
+ 1. [id="step-call-builtin-function-result"] Let _result_ be the Completion Record that is the result of evaluating _func_ in a manner that conforms to the specification of _func_. If _thisArg_ is ~uninitialized~, the *this* value is uninitialized; else _thisArg_ provides the *this* value. _argList_ provides the named parameters. _newTarget_ provides the NewTarget value.
+ 1. NOTE: If _func_ is defined in this document, “the specification of _func_” is the behaviour specified for it via algorithm steps or other means.
1. Remove _calleeContext_ from the execution context stack and restore _callerContext_ as the running execution context.
1. Return ? _result_.
@@ -13827,9 +14403,10 @@
_name_: a property key or a Private Name,
_additionalInternalSlotsList_: a List of names of internal slots,
optional _realm_: a Realm Record,
- optional _prototype_: an Object or *null*,
+ optional _proto_: an Object or *null*,
optional _prefix_: a String,
- ): a function object
+ optional _async_: a Boolean,
+ ): a built-in function object
- description
@@ -13837,11 +14414,13 @@
1. If _realm_ is not present, set _realm_ to the current Realm Record.
- 1. If _prototype_ is not present, set _prototype_ to _realm_.[[Intrinsics]].[[%Function.prototype%]].
+ 1. If _proto_ is not present, set _proto_ to _realm_.[[Intrinsics]].[[%Function.prototype%]].
+ 1. If _async_ is not present, set _async_ to *false*.
1. Let _internalSlotsList_ be a List containing the names of all the internal slots that Bound Function Exotic Objects
Bound function exotic objects do not have the internal slots of ECMAScript function objects listed in
-
-
- Internal Slot
-
-
- Type
-
-
- Description
-
-
+
+
+
+ Internal Slot
+
+
+ Type
+
+
+ Description
+
+
+
[[BoundTargetFunction]]
@@ -13919,19 +14500,19 @@ Bound Function Exotic Objects
[[Call]] (
- _thisArgument_: an ECMAScript language value,
- _argumentsList_: a List of ECMAScript language values,
+ _thisArg_: an ECMAScript language value,
+ _argList_: a List of ECMAScript language values,
): either a normal completion containing an ECMAScript language value or a throw completion
- for
- - a bound function exotic object _F_
+ - a bound function exotic object _func_
- 1. Let _target_ be _F_.[[BoundTargetFunction]].
- 1. Let _boundThis_ be _F_.[[BoundThis]].
- 1. Let _boundArgs_ be _F_.[[BoundArguments]].
- 1. Let _args_ be the list-concatenation of _boundArgs_ and _argumentsList_.
+ 1. Let _target_ be _func_.[[BoundTargetFunction]].
+ 1. Let _boundThis_ be _func_.[[BoundThis]].
+ 1. Let _boundArgs_ be _func_.[[BoundArguments]].
+ 1. Let _args_ be the list-concatenation of _boundArgs_ and _argList_.
1. Return ? Call(_target_, _boundThis_, _args_).
@@ -13939,20 +14520,20 @@
[[Construct]] (
- _argumentsList_: a List of ECMAScript language values,
+ _argList_: a List of ECMAScript language values,
_newTarget_: a constructor,
): either a normal completion containing an Object or a throw completion
- for
- - a bound function exotic object _F_
+ - a bound function exotic object _func_
- 1. Let _target_ be _F_.[[BoundTargetFunction]].
+ 1. Let _target_ be _func_.[[BoundTargetFunction]].
1. Assert: IsConstructor(_target_) is *true*.
- 1. Let _boundArgs_ be _F_.[[BoundArguments]].
- 1. Let _args_ be the list-concatenation of _boundArgs_ and _argumentsList_.
- 1. If SameValue(_F_, _newTarget_) is *true*, set _newTarget_ to _target_.
+ 1. Let _boundArgs_ be _func_.[[BoundArguments]].
+ 1. Let _args_ be the list-concatenation of _boundArgs_ and _argList_.
+ 1. If SameValue(_func_, _newTarget_) is *true*, set _newTarget_ to _target_.
1. Return ? Construct(_target_, _args_, _newTarget_).
@@ -13960,7 +14541,7 @@
BoundFunctionCreate (
- _targetFunction_: a function object,
+ _targetFunc_: a function object,
_boundThis_: an ECMAScript language value,
_boundArgs_: a List of ECMAScript language values,
): either a normal completion containing a function object or a throw completion
@@ -13970,14 +14551,14 @@
- It is used to specify the creation of new bound function exotic objects.
- 1. Let _proto_ be ? _targetFunction_.[[GetPrototypeOf]] ().
+ 1. Let _proto_ be ? _targetFunc_.[[GetPrototypeOf]]() .
1. Let _internalSlotsList_ be the list-concatenation of « [[Prototype]], [[Extensible]] » and the internal slots listed in Array Exotic Objects
[[DefineOwnProperty]] (
- _P_: a property key,
- _Desc_: a Property Descriptor,
+ _propertyKey_: a property key,
+ _propertyDesc_: a Property Descriptor,
): either a normal completion containing a Boolean or a throw completion
- for
- - an Array exotic object _A_
+ - an Array exotic object _array_
- 1. If _P_ is *"length"*, then
- 1. Return ? ArraySetLength(_A_, _Desc_).
- 1. Else if _P_ is an array index, then
- 1. Let _lengthDesc_ be OrdinaryGetOwnProperty(_A_, *"length"*).
+ 1. If _propertyKey_ is *"length"*, return ? ArraySetLength(_array_, _propertyDesc_).
+ 1. If _propertyKey_ is an array index, then
+ 1. Let _lengthDesc_ be OrdinaryGetOwnProperty(_array_, *"length"*).
+ 1. Assert: _lengthDesc_ is not *undefined*.
1. Assert: IsDataDescriptor(_lengthDesc_) is *true*.
1. Assert: _lengthDesc_.[[Configurable]] is *false*.
1. Let _length_ be _lengthDesc_.[[Value]].
1. Assert: _length_ is a non-negative integral Number.
- 1. Let _index_ be ! ToUint32(_P_).
+ 1. Let _index_ be ! ToUint32(_propertyKey_).
1. If _index_ ≥ _length_ and _lengthDesc_.[[Writable]] is *false*, return *false*.
- 1. Let _succeeded_ be ! OrdinaryDefineOwnProperty(_A_, _P_, _Desc_).
+ 1. Let _succeeded_ be ! OrdinaryDefineOwnProperty(_array_, _propertyKey_, _propertyDesc_).
1. If _succeeded_ is *false*, return *false*.
1. If _index_ ≥ _length_, then
1. Set _lengthDesc_.[[Value]] to _index_ + *1*𝔽.
- 1. Set _succeeded_ to ! OrdinaryDefineOwnProperty(_A_, *"length"*, _lengthDesc_).
+ 1. Set _succeeded_ to ! OrdinaryDefineOwnProperty(_array_, *"length"*, _lengthDesc_).
1. Assert: _succeeded_ is *true*.
1. Return *true*.
- 1. Return ? OrdinaryDefineOwnProperty(_A_, _P_, _Desc_).
+ 1. Return ? OrdinaryDefineOwnProperty(_array_, _propertyKey_, _propertyDesc_).
@@ -14038,11 +14619,11 @@
1. If _length_ > 232 - 1, throw a *RangeError* exception.
1. If _proto_ is not present, set _proto_ to %Array.prototype%.
- 1. Let _A_ be MakeBasicObject(« [[Prototype]], [[Extensible]] »).
- 1. Set _A_.[[Prototype]] to _proto_.
- 1. Set _A_.[[DefineOwnProperty]] as specified in
@@ -14060,18 +14641,18 @@
1. Let _isArray_ be ? IsArray(_originalArray_).
1. If _isArray_ is *false*, return ? ArrayCreate(_length_).
- 1. Let _C_ be ? Get(_originalArray_, *"constructor"*).
- 1. If IsConstructor(_C_) is *true*, then
+ 1. Let _ctor_ be ? Get(_originalArray_, *"constructor"*).
+ 1. If IsConstructor(_ctor_) is *true*, then
1. Let _thisRealm_ be the current Realm Record.
- 1. Let _realmC_ be ? GetFunctionRealm(_C_).
- 1. If _thisRealm_ and _realmC_ are not the same Realm Record, then
- 1. If SameValue(_C_, _realmC_.[[Intrinsics]].[[%Array%]]) is *true*, set _C_ to *undefined*.
- 1. If _C_ is an Object, then
- 1. Set _C_ to ? Get(_C_, @@species).
- 1. If _C_ is *null*, set _C_ to *undefined*.
- 1. If _C_ is *undefined*, return ? ArrayCreate(_length_).
- 1. If IsConstructor(_C_) is *false*, throw a *TypeError* exception.
- 1. Return ? Construct(_C_, « 𝔽(_length_) »).
+ 1. Let _ctorRealm_ be ? GetFunctionRealm(_ctor_).
+ 1. If _thisRealm_ and _ctorRealm_ are not the same Realm Record, then
+ 1. If SameValue(_ctor_, _ctorRealm_.[[Intrinsics]].[[%Array%]]) is *true*, set _ctor_ to *undefined*.
+ 1. If _ctor_ is an Object, then
+ 1. Set _ctor_ to ? Get(_ctor_, %Symbol.species%).
+ 1. If _ctor_ is *null*, set _ctor_ to *undefined*.
+ 1. If _ctor_ is *undefined*, return ? ArrayCreate(_length_).
+ 1. If IsConstructor(_ctor_) is *false*, throw a *TypeError* exception.
+ 1. Return ? Construct(_ctor_, « 𝔽(_length_) »).
If _originalArray_ was created using the standard built-in Array constructor for a realm that is not the realm of the running execution context, then a new Array is created using the realm of the running execution context. This maintains compatibility with Web browsers that have historically had that behaviour for the `Array.prototype` methods that now are defined using ArraySpeciesCreate.
@@ -14081,49 +14662,50 @@
ArraySetLength (
- _A_: an Array,
- _Desc_: a Property Descriptor,
+ _array_: an Array,
+ _propertyDesc_: a Property Descriptor,
): either a normal completion containing a Boolean or a throw completion
- 1. If _Desc_ does not have a [[Value]] field, then
- 1. Return ! OrdinaryDefineOwnProperty(_A_, *"length"*, _Desc_).
- 1. Let _newLenDesc_ be a copy of _Desc_.
- 1. [id="step-arraysetlength-newlen"] Let _newLen_ be ? ToUint32(_Desc_.[[Value]]).
- 1. [id="step-arraysetlength-numberlen"] Let _numberLen_ be ? ToNumber(_Desc_.[[Value]]).
- 1. If SameValueZero(_newLen_, _numberLen_) is *false*, throw a *RangeError* exception.
- 1. Set _newLenDesc_.[[Value]] to _newLen_.
- 1. Let _oldLenDesc_ be OrdinaryGetOwnProperty(_A_, *"length"*).
- 1. Assert: IsDataDescriptor(_oldLenDesc_) is *true*.
- 1. Assert: _oldLenDesc_.[[Configurable]] is *false*.
- 1. Let _oldLen_ be _oldLenDesc_.[[Value]].
- 1. If _newLen_ ≥ _oldLen_, then
- 1. Return ! OrdinaryDefineOwnProperty(_A_, *"length"*, _newLenDesc_).
- 1. If _oldLenDesc_.[[Writable]] is *false*, return *false*.
- 1. If _newLenDesc_ does not have a [[Writable]] field or _newLenDesc_.[[Writable]] is *true*, then
+ 1. If _propertyDesc_ does not have a [[Value]] field, then
+ 1. Return ! OrdinaryDefineOwnProperty(_array_, *"length"*, _propertyDesc_).
+ 1. Let _newLengthDesc_ be a copy of _propertyDesc_.
+ 1. [id="step-arraysetlength-newlen"] Let _newLength_ be ? ToUint32(_propertyDesc_.[[Value]]).
+ 1. [id="step-arraysetlength-numberlen"] Let _numberLength_ be ? ToNumber(_propertyDesc_.[[Value]]).
+ 1. If SameValueZero(_newLength_, _numberLength_) is *false*, throw a *RangeError* exception.
+ 1. Set _newLengthDesc_.[[Value]] to _newLength_.
+ 1. Let _oldLengthDesc_ be OrdinaryGetOwnProperty(_array_, *"length"*).
+ 1. Assert: _oldLengthDesc_ is not *undefined*.
+ 1. Assert: IsDataDescriptor(_oldLengthDesc_) is *true*.
+ 1. Assert: _oldLengthDesc_.[[Configurable]] is *false*.
+ 1. Let _oldLength_ be _oldLengthDesc_.[[Value]].
+ 1. If _newLength_ ≥ _oldLength_, then
+ 1. Return ! OrdinaryDefineOwnProperty(_array_, *"length"*, _newLengthDesc_).
+ 1. If _oldLengthDesc_.[[Writable]] is *false*, return *false*.
+ 1. If _newLengthDesc_ does not have a [[Writable]] field or _newLengthDesc_.[[Writable]] is *true*, then
1. Let _newWritable_ be *true*.
1. Else,
1. NOTE: Setting the [[Writable]] attribute to *false* is deferred in case any elements cannot be deleted.
1. Let _newWritable_ be *false*.
- 1. Set _newLenDesc_.[[Writable]] to *true*.
- 1. Let _succeeded_ be ! OrdinaryDefineOwnProperty(_A_, *"length"*, _newLenDesc_).
+ 1. Set _newLengthDesc_.[[Writable]] to *true*.
+ 1. Let _succeeded_ be ! OrdinaryDefineOwnProperty(_array_, *"length"*, _newLengthDesc_).
1. If _succeeded_ is *false*, return *false*.
- 1. For each own property key _P_ of _A_ such that _P_ is an array index and ! ToUint32(_P_) ≥ _newLen_, in descending numeric index order, do
- 1. Let _deleteSucceeded_ be ! _A_.[[Delete]](_P_).
+ 1. For each own property key _propertyKey_ of _array_ such that _propertyKey_ is an array index and ! ToUint32(_propertyKey_) ≥ _newLength_, in descending numeric index order, do
+ 1. Let _deleteSucceeded_ be ! _array_.[[Delete]](_propertyKey_).
1. If _deleteSucceeded_ is *false*, then
- 1. Set _newLenDesc_.[[Value]] to ! ToUint32(_P_) + *1*𝔽.
- 1. If _newWritable_ is *false*, set _newLenDesc_.[[Writable]] to *false*.
- 1. Perform ! OrdinaryDefineOwnProperty(_A_, *"length"*, _newLenDesc_).
+ 1. Set _newLengthDesc_.[[Value]] to ! ToUint32(_propertyKey_) + *1*𝔽.
+ 1. If _newWritable_ is *false*, set _newLengthDesc_.[[Writable]] to *false*.
+ 1. Perform ! OrdinaryDefineOwnProperty(_array_, *"length"*, _newLengthDesc_).
1. Return *false*.
1. If _newWritable_ is *false*, then
- 1. Set _succeeded_ to ! OrdinaryDefineOwnProperty(_A_, *"length"*, PropertyDescriptor { [[Writable]]: *false* }).
+ 1. Set _succeeded_ to ! OrdinaryDefineOwnProperty(_array_, *"length"*, PropertyDescriptor { [[Writable]]: *false* }).
1. Assert: _succeeded_ is *true*.
1. Return *true*.
- In steps
+ In steps
@@ -14139,37 +14721,37 @@ String Exotic Objects
[[GetOwnProperty]] (
- _P_: a property key,
+ _propertyKey_: a property key,
): a normal completion containing either a Property Descriptor or *undefined*
- for
- - a String exotic object _S_
+ - a String exotic object _string_
- 1. Let _desc_ be OrdinaryGetOwnProperty(_S_, _P_).
- 1. If _desc_ is not *undefined*, return _desc_.
- 1. Return StringGetOwnProperty(_S_, _P_).
+ 1. Let _propertyDesc_ be OrdinaryGetOwnProperty(_string_, _propertyKey_).
+ 1. If _propertyDesc_ is not *undefined*, return _propertyDesc_.
+ 1. Return StringGetOwnProperty(_string_, _propertyKey_).
[[DefineOwnProperty]] (
- _P_: a property key,
- _Desc_: a Property Descriptor,
+ _propertyKey_: a property key,
+ _propertyDesc_: a Property Descriptor,
): a normal completion containing a Boolean
- for
- - a String exotic object _S_
+ - a String exotic object _string_
- 1. Let _stringDesc_ be StringGetOwnProperty(_S_, _P_).
+ 1. Let _stringDesc_ be StringGetOwnProperty(_string_, _propertyKey_).
1. If _stringDesc_ is not *undefined*, then
- 1. Let _extensible_ be _S_.[[Extensible]].
- 1. Return IsCompatiblePropertyDescriptor(_extensible_, _Desc_, _stringDesc_).
- 1. Return ! OrdinaryDefineOwnProperty(_S_, _P_, _Desc_).
+ 1. Let _extensible_ be _string_.[[Extensible]].
+ 1. Return IsCompatiblePropertyDescriptor(_extensible_, _propertyDesc_, _stringDesc_).
+ 1. Return ! OrdinaryDefineOwnProperty(_string_, _propertyKey_, _propertyDesc_).
@@ -14177,21 +14759,21 @@
[[OwnPropertyKeys]] ( ): a normal completion containing a List of property keys
- for
- - a String exotic object _O_
+ - a String exotic object _obj_
1. Let _keys_ be a new empty List.
- 1. Let _str_ be _O_.[[StringData]].
- 1. Assert: _str_ is a String.
- 1. Let _len_ be the length of _str_.
- 1. For each integer _i_ such that 0 ≤ _i_ < _len_, in ascending order, do
+ 1. Let _string_ be _obj_.[[StringData]].
+ 1. Assert: _string_ is a String.
+ 1. Let _length_ be the length of _string_.
+ 1. For each integer _i_ such that 0 ≤ _i_ < _length_, in ascending order, do
1. Append ! ToString(𝔽(_i_)) to _keys_.
- 1. For each own property key _P_ of _O_ such that _P_ is an array index and ! ToIntegerOrInfinity(_P_) ≥ _len_, in ascending numeric index order, do
- 1. Append _P_ to _keys_.
- 1. For each own property key _P_ of _O_ such that _P_ is a String and _P_ is not an array index, in ascending chronological order of property creation, do
- 1. Append _P_ to _keys_.
- 1. For each own property key _P_ of _O_ such that _P_ is a Symbol, in ascending chronological order of property creation, do
- 1. Append _P_ to _keys_.
+ 1. For each own property key _propertyKey_ of _obj_ such that _propertyKey_ is an array index and ! ToIntegerOrInfinity(_propertyKey_) ≥ _length_, in ascending numeric index order, do
+ 1. Append _propertyKey_ to _keys_.
+ 1. For each own property key _propertyKey_ of _obj_ such that _propertyKey_ is a String and _propertyKey_ is not an array index, in ascending chronological order of property creation, do
+ 1. Append _propertyKey_ to _keys_.
+ 1. For each own property key _propertyKey_ of _obj_ such that _propertyKey_ is a Symbol, in ascending chronological order of property creation, do
+ 1. Append _propertyKey_ to _keys_.
1. Return _keys_.
@@ -14200,7 +14782,7 @@ [[OwnPropertyKeys]] ( ): a normal completion containing a List of property k
StringCreate (
_value_: a String,
- _prototype_: an Object,
+ _proto_: an Object,
): a String exotic object
@@ -14208,39 +14790,38 @@
- It is used to specify the creation of new String exotic objects.
- 1. Let _S_ be MakeBasicObject(« [[Prototype]], [[Extensible]], [[StringData]] »).
- 1. Set _S_.[[Prototype]] to _prototype_.
- 1. Set _S_.[[StringData]] to _value_.
- 1. Set _S_.[[GetOwnProperty]] as specified in
StringGetOwnProperty (
- _S_: an Object that has a [[StringData]] internal slot,
- _P_: a property key,
+ _string_: an Object that has a [[StringData]] internal slot,
+ _propertyKey_: a property key,
): a Property Descriptor or *undefined*
- 1. If _P_ is not a String, return *undefined*.
- 1. Let _index_ be CanonicalNumericIndexString(_P_).
- 1. If _index_ is *undefined*, return *undefined*.
- 1. If IsIntegralNumber(_index_) is *false*, return *undefined*.
- 1. If _index_ is *-0*𝔽, return *undefined*.
- 1. Let _str_ be _S_.[[StringData]].
- 1. Assert: _str_ is a String.
- 1. Let _len_ be the length of _str_.
- 1. If ℝ(_index_) < 0 or _len_ ≤ ℝ(_index_), return *undefined*.
- 1. Let _resultStr_ be the substring of _str_ from ℝ(_index_) to ℝ(_index_) + 1.
- 1. Return the PropertyDescriptor { [[Value]]: _resultStr_, [[Writable]]: *false*, [[Enumerable]]: *true*, [[Configurable]]: *false* }.
+ 1. If _propertyKey_ is not a String, return *undefined*.
+ 1. Let _numericIndex_ be CanonicalNumericIndexString(_propertyKey_).
+ 1. If _numericIndex_ is not an integral Number, return *undefined*.
+ 1. If _numericIndex_ is *-0*𝔽 or _numericIndex_ < *-0*𝔽, return *undefined*.
+ 1. Let _stringData_ be _string_.[[StringData]].
+ 1. Assert: _stringData_ is a String.
+ 1. Let _length_ be the length of _stringData_.
+ 1. If ℝ(_numericIndex_) ≥ _length_, return *undefined*.
+ 1. Let _resultString_ be the substring of _stringData_ from ℝ(_numericIndex_) to ℝ(_numericIndex_) + 1.
+ 1. Return the PropertyDescriptor { [[Value]]: _resultString_, [[Writable]]: *false*, [[Enumerable]]: *true*, [[Configurable]]: *false* }.
@@ -14256,7 +14837,7 @@ Arguments Exotic Objects
While CreateUnmappedArgumentsObject is grouped into this clause, it creates an ordinary object, not an arguments exotic object.
-
Arguments exotic objects have the same internal slots as ordinary objects. They also have a [[ParameterMap]] internal slot. Ordinary arguments objects also have a [[ParameterMap]] internal slot whose value is always undefined. For ordinary argument objects the [[ParameterMap]] internal slot is only used by `Object.prototype.toString` (
+ Arguments exotic objects have the same internal slots as ordinary objects. They also have a [[ParameterMap]] internal slot. Ordinary arguments objects also have a [[ParameterMap]] internal slot whose value is always *undefined*. For ordinary argument objects the [[ParameterMap]] internal slot is only used by `Object.prototype.toString` (
The integer-indexed data properties of an arguments exotic object whose numeric name values are less than the number of formal parameters of the corresponding function object initially share their values with the corresponding argument bindings in the function's execution context. This means that changing the property changes the corresponding value of the argument binding and vice-versa. This correspondence is broken if such a property is deleted and then redefined or if the property is changed into an accessor property. If the arguments object is an ordinary object, the values of its properties are simply a copy of the arguments passed to the function and there is no dynamic linkage between the property values and the formal parameter values.
@@ -14274,7 +14855,7 @@ Arguments Exotic Objects
[[GetOwnProperty]] (
- _P_: a property key,
+ _propertyKey_: a property key,
): a normal completion containing either a Property Descriptor or *undefined*
@@ -14282,21 +14863,21 @@
- an arguments exotic object _args_
- 1. Let _desc_ be OrdinaryGetOwnProperty(_args_, _P_).
- 1. If _desc_ is *undefined*, return *undefined*.
+ 1. Let _propertyDesc_ be OrdinaryGetOwnProperty(_args_, _propertyKey_).
+ 1. If _propertyDesc_ is *undefined*, return *undefined*.
1. Let _map_ be _args_.[[ParameterMap]].
- 1. Let _isMapped_ be ! HasOwnProperty(_map_, _P_).
+ 1. Let _isMapped_ be ! HasOwnProperty(_map_, _propertyKey_).
1. If _isMapped_ is *true*, then
- 1. Set _desc_.[[Value]] to ! Get(_map_, _P_).
- 1. Return _desc_.
+ 1. Set _propertyDesc_.[[Value]] to ! Get(_map_, _propertyKey_).
+ 1. Return _propertyDesc_.
[[DefineOwnProperty]] (
- _P_: a property key,
- _Desc_: a Property Descriptor,
+ _propertyKey_: a property key,
+ _propertyDesc_: a Property Descriptor,
): a normal completion containing a Boolean
@@ -14305,23 +14886,23 @@
1. Let _map_ be _args_.[[ParameterMap]].
- 1. Let _isMapped_ be ! HasOwnProperty(_map_, _P_).
- 1. Let _newArgDesc_ be _Desc_.
- 1. If _isMapped_ is *true* and IsDataDescriptor(_Desc_) is *true*, then
- 1. If _Desc_ does not have a [[Value]] field, _Desc_ has a [[Writable]] field, and _Desc_.[[Writable]] is *false*, then
- 1. Set _newArgDesc_ to a copy of _Desc_.
- 1. Set _newArgDesc_.[[Value]] to ! Get(_map_, _P_).
- 1. Let _allowed_ be ! OrdinaryDefineOwnProperty(_args_, _P_, _newArgDesc_).
+ 1. Let _isMapped_ be ! HasOwnProperty(_map_, _propertyKey_).
+ 1. Let _newArgDesc_ be _propertyDesc_.
+ 1. If _isMapped_ is *true* and IsDataDescriptor(_propertyDesc_) is *true*, then
+ 1. If _propertyDesc_ does not have a [[Value]] field, _propertyDesc_ has a [[Writable]] field, and _propertyDesc_.[[Writable]] is *false*, then
+ 1. Set _newArgDesc_ to a copy of _propertyDesc_.
+ 1. Set _newArgDesc_.[[Value]] to ! Get(_map_, _propertyKey_).
+ 1. Let _allowed_ be ! OrdinaryDefineOwnProperty(_args_, _propertyKey_, _newArgDesc_).
1. If _allowed_ is *false*, return *false*.
1. If _isMapped_ is *true*, then
- 1. If IsAccessorDescriptor(_Desc_) is *true*, then
- 1. Perform ! _map_.[[Delete]](_P_).
+ 1. If IsAccessorDescriptor(_propertyDesc_) is *true*, then
+ 1. Perform ! _map_.[[Delete]](_propertyKey_).
1. Else,
- 1. If _Desc_ has a [[Value]] field, then
+ 1. If _propertyDesc_ has a [[Value]] field, then
1. Assert: The following Set will succeed, since formal parameters mapped by arguments objects are always writable.
- 1. Perform ! Set(_map_, _P_, _Desc_.[[Value]], *false*).
- 1. If _Desc_ has a [[Writable]] field and _Desc_.[[Writable]] is *false*, then
- 1. Perform ! _map_.[[Delete]](_P_).
+ 1. Perform ! Set(_map_, _propertyKey_, _propertyDesc_.[[Value]], *false*).
+ 1. If _propertyDesc_ has a [[Writable]] field and _propertyDesc_.[[Writable]] is *false*, then
+ 1. Perform ! _map_.[[Delete]](_propertyKey_).
1. Return *true*.
@@ -14329,8 +14910,8 @@
[[Get]] (
- _P_: a property key,
- _Receiver_: an ECMAScript language value,
+ _propertyKey_: a property key,
+ _receiver_: an ECMAScript language value,
): either a normal completion containing an ECMAScript language value or a throw completion
@@ -14339,21 +14920,19 @@
1. Let _map_ be _args_.[[ParameterMap]].
- 1. Let _isMapped_ be ! HasOwnProperty(_map_, _P_).
- 1. If _isMapped_ is *false*, then
- 1. Return ? OrdinaryGet(_args_, _P_, _Receiver_).
- 1. Else,
- 1. Assert: _map_ contains a formal parameter mapping for _P_.
- 1. Return ! Get(_map_, _P_).
+ 1. Let _isMapped_ be ! HasOwnProperty(_map_, _propertyKey_).
+ 1. If _isMapped_ is *false*, return ? OrdinaryGet(_args_, _propertyKey_, _receiver_).
+ 1. Assert: _map_ contains a formal parameter mapping for _propertyKey_.
+ 1. Return ! Get(_map_, _propertyKey_).
[[Set]] (
- _P_: a property key,
- _V_: an ECMAScript language value,
- _Receiver_: an ECMAScript language value,
+ _propertyKey_: a property key,
+ _value_: an ECMAScript language value,
+ _receiver_: an ECMAScript language value,
): either a normal completion containing a Boolean or a throw completion
@@ -14361,22 +14940,22 @@
- an arguments exotic object _args_
- 1. If SameValue(_args_, _Receiver_) is *false*, then
+ 1. If SameValue(_args_, _receiver_) is *false*, then
1. Let _isMapped_ be *false*.
1. Else,
1. Let _map_ be _args_.[[ParameterMap]].
- 1. Let _isMapped_ be ! HasOwnProperty(_map_, _P_).
+ 1. Let _isMapped_ be ! HasOwnProperty(_map_, _propertyKey_).
1. If _isMapped_ is *true*, then
1. Assert: The following Set will succeed, since formal parameters mapped by arguments objects are always writable.
- 1. Perform ! Set(_map_, _P_, _V_, *false*).
- 1. Return ? OrdinarySet(_args_, _P_, _V_, _Receiver_).
+ 1. Perform ! Set(_map_, _propertyKey_, _value_, *false*).
+ 1. Return ? OrdinarySet(_args_, _propertyKey_, _value_, _receiver_).
[[Delete]] (
- _P_: a property key,
+ _propertyKey_: a property key,
): either a normal completion containing a Boolean or a throw completion
@@ -14385,10 +14964,10 @@
1. Let _map_ be _args_.[[ParameterMap]].
- 1. Let _isMapped_ be ! HasOwnProperty(_map_, _P_).
- 1. Let _result_ be ? OrdinaryDelete(_args_, _P_).
+ 1. Let _isMapped_ be ! HasOwnProperty(_map_, _propertyKey_).
+ 1. Let _result_ be ? OrdinaryDelete(_args_, _propertyKey_).
1. If _result_ is *true* and _isMapped_ is *true*, then
- 1. Perform ! _map_.[[Delete]](_P_).
+ 1. Perform ! _map_.[[Delete]](_propertyKey_).
1. Return _result_.
@@ -14396,23 +14975,23 @@
CreateUnmappedArgumentsObject (
- _argumentsList_: a List of ECMAScript language values,
+ _argList_: a List of ECMAScript language values,
): an ordinary object
- 1. Let _len_ be the number of elements in _argumentsList_.
+ 1. Let _length_ be the number of elements in _argList_.
1. Let _obj_ be OrdinaryObjectCreate(%Object.prototype%, « [[ParameterMap]] »).
1. Set _obj_.[[ParameterMap]] to *undefined*.
- 1. Perform ! DefinePropertyOrThrow(_obj_, *"length"*, PropertyDescriptor { [[Value]]: 𝔽(_len_), [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
+ 1. Perform ! DefinePropertyOrThrow(_obj_, *"length"*, PropertyDescriptor { [[Value]]: 𝔽(_length_), [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
1. Let _index_ be 0.
- 1. Repeat, while _index_ < _len_,
- 1. Let _val_ be _argumentsList_[_index_].
- 1. Perform ! CreateDataPropertyOrThrow(_obj_, ! ToString(𝔽(_index_)), _val_).
+ 1. Repeat, while _index_ < _length_,
+ 1. Let _value_ be _argList_[_index_].
+ 1. Perform ! CreateDataPropertyOrThrow(_obj_, ! ToString(𝔽(_index_)), _value_).
1. Set _index_ to _index_ + 1.
- 1. Perform ! DefinePropertyOrThrow(_obj_, @@iterator, PropertyDescriptor { [[Value]]: %Array.prototype.values%, [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
- 1. Perform ! DefinePropertyOrThrow(_obj_, *"callee"*, PropertyDescriptor { [[Get]]: %ThrowTypeError%, [[Set]]: %ThrowTypeError%, [[Enumerable]]: *false*, [[Configurable]]: *false* }).
+ 1. Perform ! DefinePropertyOrThrow(_obj_, %Symbol.iterator%, PropertyDescriptor { [[Value]]: %Array.prototype.values%, [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
+ 1. Perform ! DefinePropertyOrThrow(_obj_, *"callee"*, PropertyDescriptor { [[Getter]]: %ThrowTypeError%, [[Setter]]: %ThrowTypeError%, [[Enumerable]]: *false*, [[Configurable]]: *false* }).
1. Return _obj_.
@@ -14420,17 +14999,17 @@
CreateMappedArgumentsObject (
- _func_: an Object,
+ _func_: an ECMAScript function object,
_formals_: a Parse Node,
- _argumentsList_: a List of ECMAScript language values,
- _env_: an Environment Record,
+ _argList_: a List of ECMAScript language values,
+ _envRecord_: an Environment Record,
): an arguments exotic object
1. Assert: _formals_ does not contain a rest parameter, any binding patterns, or any initializers. It may contain duplicate identifiers.
- 1. Let _len_ be the number of elements in _argumentsList_.
+ 1. Let _length_ be the number of elements in _argList_.
1. Let _obj_ be MakeBasicObject(« [[Prototype]], [[Extensible]], [[ParameterMap]] »).
1. Set _obj_.[[GetOwnProperty]] as specified in
1. Set _obj_.[[Prototype]] to %Object.prototype%.
1. Let _map_ be OrdinaryObjectCreate(*null*).
1. Set _obj_.[[ParameterMap]] to _map_.
- 1. Let _parameterNames_ be the BoundNames of _formals_.
- 1. Let _numberOfParameters_ be the number of elements in _parameterNames_.
+ 1. Let _paramNames_ be the BoundNames of _formals_.
+ 1. Let _paramCount_ be the number of elements in _paramNames_.
1. Let _index_ be 0.
- 1. Repeat, while _index_ < _len_,
- 1. Let _val_ be _argumentsList_[_index_].
- 1. Perform ! CreateDataPropertyOrThrow(_obj_, ! ToString(𝔽(_index_)), _val_).
+ 1. Repeat, while _index_ < _length_,
+ 1. Let _value_ be _argList_[_index_].
+ 1. Perform ! CreateDataPropertyOrThrow(_obj_, ! ToString(𝔽(_index_)), _value_).
1. Set _index_ to _index_ + 1.
- 1. Perform ! DefinePropertyOrThrow(_obj_, *"length"*, PropertyDescriptor { [[Value]]: 𝔽(_len_), [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
+ 1. Perform ! DefinePropertyOrThrow(_obj_, *"length"*, PropertyDescriptor { [[Value]]: 𝔽(_length_), [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
1. Let _mappedNames_ be a new empty List.
- 1. Set _index_ to _numberOfParameters_ - 1.
+ 1. Set _index_ to _paramCount_ - 1.
1. Repeat, while _index_ ≥ 0,
- 1. Let _name_ be _parameterNames_[_index_].
+ 1. Let _name_ be _paramNames_[_index_].
1. If _mappedNames_ does not contain _name_, then
1. Append _name_ to _mappedNames_.
- 1. If _index_ < _len_, then
- 1. Let _g_ be MakeArgGetter(_name_, _env_).
- 1. Let _p_ be MakeArgSetter(_name_, _env_).
- 1. Perform ! _map_.[[DefineOwnProperty]](! ToString(𝔽(_index_)), PropertyDescriptor { [[Set]]: _p_, [[Get]]: _g_, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
+ 1. If _index_ < _length_, then
+ 1. Let _getter_ be MakeArgGetter(_name_, _envRecord_).
+ 1. Let _setter_ be MakeArgSetter(_name_, _envRecord_).
+ 1. Perform ! _map_.[[DefineOwnProperty]](! ToString(𝔽(_index_)), PropertyDescriptor { [[Setter]]: _setter_, [[Getter]]: _getter_, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
1. Set _index_ to _index_ - 1.
- 1. Perform ! DefinePropertyOrThrow(_obj_, @@iterator, PropertyDescriptor { [[Value]]: %Array.prototype.values%, [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
+ 1. Perform ! DefinePropertyOrThrow(_obj_, %Symbol.iterator%, PropertyDescriptor { [[Value]]: %Array.prototype.values%, [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
1. Perform ! DefinePropertyOrThrow(_obj_, *"callee"*, PropertyDescriptor { [[Value]]: _func_, [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
1. Return _obj_.
@@ -14468,16 +15047,16 @@
MakeArgGetter (
_name_: a String,
- _env_: an Environment Record,
+ _envRecord_: an Environment Record,
): a function object
- description
- - It creates a built-in function object that when executed returns the value bound for _name_ in _env_.
+ - It creates a built-in function object that when executed returns the value bound for _name_ in _envRecord_.
- 1. Let _getterClosure_ be a new Abstract Closure with no parameters that captures _name_ and _env_ and performs the following steps when called:
- 1. Return _env_.GetBindingValue(_name_, *false*).
+ 1. Let _getterClosure_ be a new Abstract Closure with no parameters that captures _name_ and _envRecord_ and performs the following steps when called:
+ 1. Return NormalCompletion(! _envRecord_.GetBindingValue(_name_, *false*)).
1. Let _getter_ be CreateBuiltinFunction(_getterClosure_, 0, *""*, « »).
1. NOTE: _getter_ is never directly accessible to ECMAScript code.
1. Return _getter_.
@@ -14488,16 +15067,16 @@
MakeArgSetter (
_name_: a String,
- _env_: an Environment Record,
+ _envRecord_: an Environment Record,
): a function object
- description
- - It creates a built-in function object that when executed sets the value bound for _name_ in _env_.
+ - It creates a built-in function object that when executed sets the value bound for _name_ in _envRecord_.
- 1. Let _setterClosure_ be a new Abstract Closure with parameters (_value_) that captures _name_ and _env_ and performs the following steps when called:
- 1. Return ! _env_.SetMutableBinding(_name_, _value_, *false*).
+ 1. Let _setterClosure_ be a new Abstract Closure with parameters (_value_) that captures _name_ and _envRecord_ and performs the following steps when called:
+ 1. Return NormalCompletion(! _envRecord_.SetMutableBinding(_name_, _value_, *false*)).
1. Let _setter_ be CreateBuiltinFunction(_setterClosure_, 1, *""*, « »).
1. NOTE: _setter_ is never directly accessible to ECMAScript code.
1. Return _setter_.
@@ -14508,135 +15087,152 @@
TypedArray Exotic Objects
- A TypedArray is an exotic object that performs special handling of integer index property keys.
- TypedArrays have the same internal slots as ordinary objects and additionally [[ViewedArrayBuffer]], [[ArrayLength]], [[ByteOffset]], [[ContentType]], and [[TypedArrayName]] internal slots.
- An object is a TypedArray if its [[GetOwnProperty]], [[HasProperty]], [[DefineOwnProperty]], [[Get]], [[Set]], [[Delete]], and [[OwnPropertyKeys]] internal methods use the definitions in this section, and its other essential internal methods use the definitions found in
+ A TypedArray is an exotic object that performs special handling of property keys that are canonical numeric strings, using the subset that are in-bounds integer indices to index elements of uniform type and enforcing the invariant that the remainder are absent without incurring prototype chain traversal.
+
+ Because ToString(_n_) for any Number _n_ is a canonical numeric string, an implementation may treat Numbers as property keys for TypedArrays without actually performing the string conversion.
+
+ TypedArrays have the same internal slots as ordinary objects and additionally [[ViewedArrayBuffer]], [[TypedArrayName]], [[ContentType]], [[ByteLength]], [[ByteOffset]], and [[ArrayLength]] internal slots.
+ An object is a TypedArray if its [[PreventExtensions]], [[GetOwnProperty]], [[HasProperty]], [[DefineOwnProperty]], [[Get]], [[Set]], [[Delete]], and [[OwnPropertyKeys]], internal methods use the definitions in this section, and its other essential internal methods use the definitions found in
+
+
+ [[PreventExtensions]] ( ): a normal completion containing a Boolean
+
+ - for
+ - a TypedArray _obj_
+
+
+ 1. NOTE: The extensibility-related invariants specified in
+
[[GetOwnProperty]] (
- _P_: a property key,
+ _propertyKey_: a property key,
): a normal completion containing either a Property Descriptor or *undefined*
- for
- - a TypedArray _O_
+ - a TypedArray _obj_
- 1. If _P_ is a String, then
- 1. Let _numericIndex_ be CanonicalNumericIndexString(_P_).
+ 1. If _propertyKey_ is a String, then
+ 1. Let _numericIndex_ be CanonicalNumericIndexString(_propertyKey_).
1. If _numericIndex_ is not *undefined*, then
- 1. Let _value_ be TypedArrayGetElement(_O_, _numericIndex_).
+ 1. Let _value_ be TypedArrayGetElement(_obj_, _numericIndex_).
1. If _value_ is *undefined*, return *undefined*.
1. Return the PropertyDescriptor { [[Value]]: _value_, [[Writable]]: *true*, [[Enumerable]]: *true*, [[Configurable]]: *true* }.
- 1. Return OrdinaryGetOwnProperty(_O_, _P_).
+ 1. Return OrdinaryGetOwnProperty(_obj_, _propertyKey_).
[[HasProperty]] (
- _P_: a property key,
+ _propertyKey_: a property key,
): either a normal completion containing a Boolean or a throw completion
- for
- - a TypedArray _O_
+ - a TypedArray _obj_
- 1. If _P_ is a String, then
- 1. Let _numericIndex_ be CanonicalNumericIndexString(_P_).
- 1. If _numericIndex_ is not *undefined*, return IsValidIntegerIndex(_O_, _numericIndex_).
- 1. Return ? OrdinaryHasProperty(_O_, _P_).
+ 1. If _propertyKey_ is a String, then
+ 1. Let _numericIndex_ be CanonicalNumericIndexString(_propertyKey_).
+ 1. If _numericIndex_ is not *undefined*, return IsValidIntegerIndex(_obj_, _numericIndex_).
+ 1. Return ? OrdinaryHasProperty(_obj_, _propertyKey_).
[[DefineOwnProperty]] (
- _P_: a property key,
- _Desc_: a Property Descriptor,
+ _propertyKey_: a property key,
+ _propertyDesc_: a Property Descriptor,
): either a normal completion containing a Boolean or a throw completion
- for
- - a TypedArray _O_
+ - a TypedArray _obj_
- 1. If _P_ is a String, then
- 1. Let _numericIndex_ be CanonicalNumericIndexString(_P_).
+ 1. If _propertyKey_ is a String, then
+ 1. Let _numericIndex_ be CanonicalNumericIndexString(_propertyKey_).
1. If _numericIndex_ is not *undefined*, then
- 1. If IsValidIntegerIndex(_O_, _numericIndex_) is *false*, return *false*.
- 1. If _Desc_ has a [[Configurable]] field and _Desc_.[[Configurable]] is *false*, return *false*.
- 1. If _Desc_ has an [[Enumerable]] field and _Desc_.[[Enumerable]] is *false*, return *false*.
- 1. If IsAccessorDescriptor(_Desc_) is *true*, return *false*.
- 1. If _Desc_ has a [[Writable]] field and _Desc_.[[Writable]] is *false*, return *false*.
- 1. If _Desc_ has a [[Value]] field, perform ? TypedArraySetElement(_O_, _numericIndex_, _Desc_.[[Value]]).
+ 1. If IsValidIntegerIndex(_obj_, _numericIndex_) is *false*, return *false*.
+ 1. If _propertyDesc_ has a [[Configurable]] field and _propertyDesc_.[[Configurable]] is *false*, return *false*.
+ 1. If _propertyDesc_ has an [[Enumerable]] field and _propertyDesc_.[[Enumerable]] is *false*, return *false*.
+ 1. If IsAccessorDescriptor(_propertyDesc_) is *true*, return *false*.
+ 1. If _propertyDesc_ has a [[Writable]] field and _propertyDesc_.[[Writable]] is *false*, return *false*.
+ 1. If _propertyDesc_ has a [[Value]] field, perform ? TypedArraySetElement(_obj_, _numericIndex_, _propertyDesc_.[[Value]]).
1. Return *true*.
- 1. Return ! OrdinaryDefineOwnProperty(_O_, _P_, _Desc_).
+ 1. Return ! OrdinaryDefineOwnProperty(_obj_, _propertyKey_, _propertyDesc_).
[[Get]] (
- _P_: a property key,
- _Receiver_: an ECMAScript language value,
+ _propertyKey_: a property key,
+ _receiver_: an ECMAScript language value,
): either a normal completion containing an ECMAScript language value or a throw completion
- for
- - a TypedArray _O_
+ - a TypedArray _obj_
- 1. If _P_ is a String, then
- 1. Let _numericIndex_ be CanonicalNumericIndexString(_P_).
+ 1. If _propertyKey_ is a String, then
+ 1. Let _numericIndex_ be CanonicalNumericIndexString(_propertyKey_).
1. If _numericIndex_ is not *undefined*, then
- 1. Return TypedArrayGetElement(_O_, _numericIndex_).
- 1. Return ? OrdinaryGet(_O_, _P_, _Receiver_).
+ 1. Return TypedArrayGetElement(_obj_, _numericIndex_).
+ 1. Return ? OrdinaryGet(_obj_, _propertyKey_, _receiver_).
[[Set]] (
- _P_: a property key,
- _V_: an ECMAScript language value,
- _Receiver_: an ECMAScript language value,
+ _propertyKey_: a property key,
+ _value_: an ECMAScript language value,
+ _receiver_: an ECMAScript language value,
): either a normal completion containing a Boolean or a throw completion
- for
- - a TypedArray _O_
+ - a TypedArray _obj_
- 1. If _P_ is a String, then
- 1. Let _numericIndex_ be CanonicalNumericIndexString(_P_).
+ 1. If _propertyKey_ is a String, then
+ 1. Let _numericIndex_ be CanonicalNumericIndexString(_propertyKey_).
1. If _numericIndex_ is not *undefined*, then
- 1. If SameValue(_O_, _Receiver_) is *true*, then
- 1. Perform ? TypedArraySetElement(_O_, _numericIndex_, _V_).
+ 1. If SameValue(_obj_, _receiver_) is *true*, then
+ 1. Perform ? TypedArraySetElement(_obj_, _numericIndex_, _value_).
1. Return *true*.
- 1. If IsValidIntegerIndex(_O_, _numericIndex_) is *false*, return *true*.
- 1. Return ? OrdinarySet(_O_, _P_, _V_, _Receiver_).
+ 1. If IsValidIntegerIndex(_obj_, _numericIndex_) is *false*, return *true*.
+ 1. Return ? OrdinarySet(_obj_, _propertyKey_, _value_, _receiver_).
[[Delete]] (
- _P_: a property key,
+ _propertyKey_: a property key,
): a normal completion containing a Boolean
- for
- - a TypedArray _O_
+ - a TypedArray _obj_
- 1. If _P_ is a String, then
- 1. Let _numericIndex_ be CanonicalNumericIndexString(_P_).
+ 1. If _propertyKey_ is a String, then
+ 1. Let _numericIndex_ be CanonicalNumericIndexString(_propertyKey_).
1. If _numericIndex_ is not *undefined*, then
- 1. If IsValidIntegerIndex(_O_, _numericIndex_) is *false*, return *true*; else return *false*.
- 1. Return ! OrdinaryDelete(_O_, _P_).
+ 1. If IsValidIntegerIndex(_obj_, _numericIndex_) is *false*, return *true*.
+ 1. Return *false*.
+ 1. Return ! OrdinaryDelete(_obj_, _propertyKey_).
@@ -14644,40 +15240,42 @@
[[OwnPropertyKeys]] ( ): a normal completion containing a List of property keys
- for
- - a TypedArray _O_
+ - a TypedArray _obj_
- 1. Let _taRecord_ be MakeTypedArrayWithBufferWitnessRecord(_O_, ~seq-cst~).
+ 1. Let _taRecord_ be MakeTypedArrayWithBufferWitnessRecord(_obj_, ~seq-cst~).
1. Let _keys_ be a new empty List.
1. If IsTypedArrayOutOfBounds(_taRecord_) is *false*, then
1. Let _length_ be TypedArrayLength(_taRecord_).
1. For each integer _i_ such that 0 ≤ _i_ < _length_, in ascending order, do
1. Append ! ToString(𝔽(_i_)) to _keys_.
- 1. For each own property key _P_ of _O_ such that _P_ is a String and _P_ is not an integer index, in ascending chronological order of property creation, do
- 1. Append _P_ to _keys_.
- 1. For each own property key _P_ of _O_ such that _P_ is a Symbol, in ascending chronological order of property creation, do
- 1. Append _P_ to _keys_.
+ 1. For each own property key _propertyKey_ of _obj_ such that _propertyKey_ is a String and _propertyKey_ is not an integer index, in ascending chronological order of property creation, do
+ 1. Append _propertyKey_ to _keys_.
+ 1. For each own property key _propertyKey_ of _obj_ such that _propertyKey_ is a Symbol, in ascending chronological order of property creation, do
+ 1. Append _propertyKey_ to _keys_.
1. Return _keys_.
TypedArray With Buffer Witness Records
- An TypedArray With Buffer Witness Record is a Record value used to encapsulate a TypedArray along with a cached byte length of the viewed buffer. It is used to help ensure there is a single shared memory read event of the byte length data block when the viewed buffer is a growable SharedArrayBuffer.
+ An TypedArray With Buffer Witness Record is a Record used to encapsulate a TypedArray along with a cached byte length of the viewed buffer. It is used to help ensure there is a single ReadSharedMemory event of the byte length data block when the viewed buffer is a growable SharedArrayBuffer.
TypedArray With Buffer Witness Records have the fields listed in
-
-
- Field Name
-
-
- Value
-
-
- Meaning
-
-
+
+
+
+ Field Name
+
+
+ Value
+
+
+ Meaning
+
+
+
[[Object]]
@@ -14726,7 +15324,7 @@
TypedArrayCreate (
- _prototype_: an Object,
+ _proto_: an Object,
): a TypedArray
@@ -14735,16 +15333,17 @@
The Symbol Type
The Symbol type is the set of all non-String values that may be used as the key of an Object property (
Each possible Symbol value is unique and immutable.
-Each Symbol value immutably holds an associated value called [[Description]] that is either *undefined* or a String value.
+Each Symbol is unique and immutable.
+Each Symbol has an immutable [[Description]] internal slot whose value is either a String or *undefined*.
Well-Known Symbols
Well-known symbols are built-in Symbol values that are explicitly referenced by algorithms of this specification. They are typically used as the keys of properties whose values serve as extension points of a specification algorithm. Unless otherwise specified, well-known symbols values are shared by all realms (
Within this specification a well-known symbol is referred to by using a notation of the form @@name, where “name” is one of the values listed in
Within this specification a well-known symbol is referred to using the standard
| + Specification Name + | ++ [[Description]] + | ++ Value and Purpose + | +||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| - Specification Name - | -- [[Description]] - | -- Value and Purpose - | ++ %Symbol.asyncDispose% + | ++ *"Symbol.asyncDispose"* + | ++ A method that asynchronously performs resource cleanup on an object. Called by AsyncDisposableStack objects and `await using` declarations when evaluation of their containing scope completes. + | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| - @@asyncIterator + %Symbol.asyncIterator% | *"Symbol.asyncIterator"* | - A method that returns the default AsyncIterator for an object. Called by the semantics of the `for`-`await`-`of` statement. + A method that returns the default async iterator for an object. Called by the semantics of the `for`-`await`-`of` statement. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| - @@hasInstance + %Symbol.dispose% + | ++ *"Symbol.dispose"* + | ++ A method that performs explicit resource cleanup on an object. Called by DisposableStack objects, AsyncDisposableStack objects, and `using` declarations when evaluation of their containing scope completes. + | +||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| + %Symbol.hasInstance% |
*"Symbol.hasInstance"*
@@ -1245,7 +1379,7 @@ Well-Known Symbols | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| - @@isConcatSpreadable + %Symbol.isConcatSpreadable% |
*"Symbol.isConcatSpreadable"*
@@ -1256,18 +1390,18 @@ Well-Known Symbols | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| - @@iterator + %Symbol.iterator% | *"Symbol.iterator"* | - A method that returns the default Iterator for an object. Called by the semantics of the for-of statement. + A method that returns the default iterator for an object. Called by the semantics of the for-of statement. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| - @@match + %Symbol.match% |
*"Symbol.match"*
@@ -1278,18 +1412,18 @@ Well-Known Symbols | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| - @@matchAll + %Symbol.matchAll% | *"Symbol.matchAll"* |
- A regular expression method that returns an iterator, that yields matches of the regular expression against a string. Called by the |
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| - @@replace + %Symbol.replace% |
*"Symbol.replace"*
@@ -1300,7 +1434,7 @@ Well-Known Symbols | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| - @@search + %Symbol.search% |
*"Symbol.search"*
@@ -1311,7 +1445,7 @@ Well-Known Symbols | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| - @@species + %Symbol.species% |
*"Symbol.species"*
@@ -1322,7 +1456,7 @@ Well-Known Symbols | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| - @@split + %Symbol.split% |
*"Symbol.split"*
@@ -1333,7 +1467,7 @@ Well-Known Symbols | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| - @@toPrimitive + %Symbol.toPrimitive% |
*"Symbol.toPrimitive"*
@@ -1344,7 +1478,7 @@ Well-Known Symbols | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| - @@toStringTag + %Symbol.toStringTag% |
*"Symbol.toStringTag"*
@@ -1355,7 +1489,7 @@ Well-Known Symbols | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| - @@unscopables + %Symbol.unscopables% |
*"Symbol.unscopables"*
@@ -1371,23 +1505,25 @@ Well-Known SymbolsNumeric Types-ECMAScript has two built-in numeric types: Number and BigInt. The following abstract operations are defined over these numeric types. The "Result" column shows the return type, along with an indication if it is possible for some invocations of the operation to return an abrupt completion. +ECMAScript has two built-in numeric types: Number and BigInt. The following abstract operations are defined over these numeric types. The “Result” column shows the return type, along with an indication if it is possible for some invocations of the operation to return an abrupt completion.
|