Symbol.iterator

The Symbol.iterator static data property represents the well-known symbol Symbol.iterator. The iterable protocol looks up this symbol for the method that returns the iterator for an object. In order for an object to be iterable, it must have a [Symbol.iterator] key.

Whenever an object needs to be iterated (such as at the beginning of a for…of loop), its Symbol.iterator method is called with no arguments, and the returned iterator is used to obtain the values to be iterated.

Some built-in types have a default iteration behavior, while other types (such as Object) do not. Some built-in types with a Symbol.iterator method are: