JS: Iterable Interface

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 has Iterator Interface.

Example

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

const aa = [3, 4, 5];

// array has an inherited property key Symbol.iterator
console.log(Reflect.has(aa, Symbol.iterator));

// not its own property
console.log(
  aa.hasOwnProperty(Symbol.iterator) === false,
);

// the property Symbol.iterator of array is inherited from Array.prototype
console.log(
  Reflect.apply(
    Object.prototype.hasOwnProperty,
    Array.prototype,
    [Symbol.iterator],
  ),
);