JS: Iterable Interface

By Xah Lee. Date: . Last updated: .

Object having Iterable Interface is called Iterable Object.

It must have the property Symbol.iterator, owned or inherited.

Iterable Interface Properties

Symbol.iterator

Symbol.iterator is a Symbol.

  • Value must be a function.
  • This function's return value must be an object that conforms to the Iterator Interface.

Example

array is iterable object. Because it has inherited property key Symbol.iterator.

// array has an inherited property key Symbol.iterator
console.log(Reflect.has([3, 4], Symbol.iterator));

// not its own property
console.log(Object.hasOwn([3, 4], Symbol.iterator) === false);

// the property Symbol.iterator of array is inherited from Array.prototype
console.log(Object.hasOwn(Array.prototype, Symbol.iterator));
// true