The toLocaleString() method of Temporal.PlainDate instances returns a string with a language-sensitive representation of this date. In implementations with Intl.DateTimeFormat API support, this method delegates to Intl.DateTimeFormat.

The getMonth() method of Date instances returns the month for this date according to local time, as a zero-based value (where zero indicates the first month of the year).

An iterator that yields the current count and the element during iteration.

An iterator that yields `None` forever after the underlying iterator yields `None` once.

The getTimeZones() method of Intl.Locale instances returns a list of supported time zones for this locale.

The spread (...) syntax allows an iterable, such as an array or string, to be expanded in places where zero or more arguments (for function calls) or elements (for array literals) are expected. In an object literal, the spread syntax enumerates the properties of an object and adds the key-value pairs to the object being created.

The async function* declaration creates a binding of a new async generator function to a given name.

The JavaScript exception "duplicate capture group name in regular expression" occurs when a regular expression pattern contains two or more named capturing groups with the same name, and these capture groups could be matched at the same time.

The JavaScript exception "parameter after rest parameter" occurs when a rest parameter is followed by anything else in a parameter list, including another rest parameter, a formal parameter, or a trailing comma.

This page introduces the basic infrastructure of the JavaScript runtime environment. The model is largely theoretical and abstract, without any platform-specific or implementation-specific details. Modern JavaScript engines heavily optimize the described semantics.