es.array.iterator.js

'use strict';
var toIndexedObject = require('../internals/to-indexed-object');
var addToUnscopables = require('../internals/add-to-unscopables');
var Iterators = require('../internals/iterators');
var InternalStateModule = require('../internals/internal-state');
var defineIterator = require('../internals/define-iterator');

var ARRAY_ITERATOR = 'Array Iterator';
var setInternalState = InternalStateModule.set;
var getInternalState = InternalStateModule.getterFor(ARRAY_ITERATOR);

// `Array.prototype.entries` method
// https://tc39.github.io/ecma262/#sec-array.prototype.entries
// `Array.prototype.keys` method
// https://tc39.github.io/ecma262/#sec-array.prototype.keys
// `Array.prototype.values` method
// https://tc39.github.io/ecma262/#sec-array.prototype.values
// `Array.prototype[@@iterator]` method
// https://tc39.github.io/ecma262/#sec-array.prototype-@@iterator
// `CreateArrayIterator` internal method
// https://tc39.github.io/ecma262/#sec-createarrayiterator
module.exports = defineIterator(Array, 'Array', function (iterated, kind) {
  setInternalState(this, {
    type: ARRAY_ITERATOR,
    target: toIndexedObject(iterated), // target
    index: 0,                          // next index
    kind: kind                         // kind
  });
// `%ArrayIteratorPrototype%.next` method
// https://tc39.github.io/ecma262/#sec-%arrayiteratorprototype%.next
}, function () {
  var state = getInternalState(this);
  var target = state.target;
  var kind = state.kind;
  var index = state.index++;
  if (!target || index >= target.length) {
    state.target = undefined;
    return { value: undefined, done: true };
  }
  if (kind == 'keys') return { value: index, done: false };
  if (kind == 'values') return { value: target[index], done: false };
  return { value: [index, target[index]], done: false };
}, 'values');

// argumentsList[@@iterator] is %ArrayProto_values%
// https://tc39.github.io/ecma262/#sec-createunmappedargumentsobject
// https://tc39.github.io/ecma262/#sec-createmappedargumentsobject
Iterators.Arguments = Iterators.Array;

// https://tc39.github.io/ecma262/#sec-array.prototype-@@unscopables
addToUnscopables('keys');
addToUnscopables('values');
addToUnscopables('entries');