Chapter 7 says:
"
If you're checking to see if an variable has been defined, you'll still need to use typeof otherwise you'll get a ReferenceError.
if typeof aVar isnt "undefined"
objectType = type(aVar)
Or more succinctly with the existential operator:
"
However, the two statements are NOT equivalent, because type(aVar?) will unconditionally return "boolean", because applying the existential operator to a variable always returns a Boolean.
Chapter 7 says:
"
If you're checking to see if an variable has been defined, you'll still need to use typeof otherwise you'll get a ReferenceError.
Or more succinctly with the existential operator:
"
However, the two statements are NOT equivalent, because
type(aVar?)will unconditionally return"boolean", because applying the existential operator to a variable always returns a Boolean.