`dns.lookup()` and `dnsPromises.lookup()` options type coercion

[AugustinMauroy]

Description

Since using non-proper types for options in dns.lookup() and dnsPromises.lookup() is deprecated (DEP0153) and has reached End-of-Life status in Node.js v18.0.0, we should provide a codemod to replace them.

• The codemod should ensure family option is a nullish value or an integer.
• The codemod should ensure hints option is a nullish value or a number.
• The codemod should ensure all option is a nullish value or a boolean.
• The codemod should ensure verbatim option is a nullish value or a boolean.
• The codemod should add explicit type conversions where needed.

Additional Information

Note that in Node.js v18.0.0, passing non-proper types for dns.lookup options now throws an ERR_INVALID_ARG_TYPE error. This change enforces proper type usage:

• family: must be undefined, null, or an integer (0, 4, or 6)
• hints: must be undefined, null, or a number
• all: must be undefined, null, or a boolean
• verbatim: must be undefined, null, or a boolean

The automatic type coercion was removed to prevent unexpected behavior and make the API more predictable.

Examples

Example 1: String family option

Before:

const dns = require("node:dns");

dns.lookup("example.com", { family: "4" }, (err, address) => {
  console.log(address);
});

After:

const dns = require("node:dns");

dns.lookup("example.com", { family: 4 }, (err, address) => {
  console.log(address);
});

Example 2: String all option

Before:

const dns = require("node:dns");

dns.lookup("example.com", { all: "true" }, (err, addresses) => {
  console.log(addresses);
});

After:

const dns = require("node:dns");

dns.lookup("example.com", { all: true }, (err, addresses) => {
  console.log(addresses);
});

Example 3: Number verbatim option

Before:

const dns = require("node:dns");

dns.lookup("example.com", { verbatim: 1 }, (err, address) => {
  console.log(address);
});

After:

const dns = require("node:dns");

dns.lookup("example.com", { verbatim: true }, (err, address) => {
  console.log(address);
});

Example 4: Promises API with string family

Before:

const { lookup } = require("node:dns").promises;

const address = await lookup("example.com", { family: "6" });

After:

const { lookup } = require("node:dns").promises;

const address = await lookup("example.com", { family: 6 });

Example 5: ESM with multiple invalid options

Before:

import { lookup } from "node:dns/promises";

const result = await lookup("example.com", {
  family: "4",
  all: 1,
  verbatim: 0
});

After:

import { lookup } from "node:dns/promises";

const result = await lookup("example.com", {
  family: 4,
  all: true,
  verbatim: false
});

Example 6: Dynamic family value

Before:

const dns = require("node:dns");

const familyStr = "4";
dns.lookup("example.com", { family: familyStr }, callback);

After:

const dns = require("node:dns");

const familyStr = "4";
dns.lookup("example.com", { family: parseInt(familyStr, 10) }, callback);

Example 7: Hints option with string

Before:

const dns = require("node:dns");

dns.lookup("example.com", { hints: "0" }, (err, address) => {
  console.log(address);
});

After:

const dns = require("node:dns");

dns.lookup("example.com", { hints: 0 }, (err, address) => {
  console.log(address);
});

Example 8: Valid options (no change needed)

Before:

const dns = require("node:dns");

dns.lookup("example.com", {
  family: 4,
  hints: dns.ADDRCONFIG,
  all: false,
  verbatim: true
}, (err, address) => {
  console.log(address);
});

After:

const dns = require("node:dns");

dns.lookup("example.com", {
  family: 4,
  hints: dns.ADDRCONFIG,
  all: false,
  verbatim: true
}, (err, address) => {
  console.log(address);
});

Example 9: Null and undefined values (no change needed)

Before:

const dns = require("node:dns");

dns.lookup("example.com", {
  family: undefined,
  all: null,
  verbatim: undefined
}, callback);

After:

const dns = require("node:dns");

dns.lookup("example.com", {
  family: undefined,
  all: null,
  verbatim: undefined
}, callback);

Refs

• DEP0153: dns.lookup and dnsPromises.lookup options type coercion
• dns.lookup options type coercion removal node#41431