core-js/modules/es.iterator.from.js

Standard library

'use strict';
var $ = require('../internals/export');
var call = require('../internals/function-call');
var toObject = require('../internals/to-object');
var isPrototypeOf = require('../internals/object-is-prototype-of');
var IteratorPrototype = require('../internals/iterators-core').IteratorPrototype;
var createIteratorProxy = require('../internals/iterator-create-proxy');
var getIteratorFlattenable = require('../internals/get-iterator-flattenable');
var IS_PURE = require('../internals/is-pure');

var FORCED = IS_PURE || function () {
  // Should not throw when an underlying iterator's `return` method is null
  // https://bugs.webkit.org/show_bug.cgi?id=288714
  try {
    // eslint-disable-next-line es/no-iterator -- required for testing
    Iterator.from({ 'return': null })['return']();
  } catch (error) {
    return true;
  }
}();

var IteratorProxy = createIteratorProxy(function () {
  return call(this.next, this.iterator);
}, true);

// `Iterator.from` method
// https://tc39.es/ecma262/#sec-iterator.from
$({ target: 'Iterator', stat: true, forced: FORCED }, {
  from: function from(O) {
    var iteratorRecord = getIteratorFlattenable(typeof O == 'string' ? toObject(O) : O, true);
    return isPrototypeOf(IteratorPrototype, iteratorRecord.iterator)
      ? iteratorRecord.iterator
      : new IteratorProxy(iteratorRecord);
  }
});