87 lines
1.7 KiB
JavaScript
87 lines
1.7 KiB
JavaScript
/**
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* Copyright (c) 2013-present, Facebook, Inc.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*
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* @providesModule Array.es6
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* @polyfill
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* @nolint
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*/
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/* eslint-disable consistent-this */
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/**
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* Creates an array from array like objects.
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*
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* https://people.mozilla.org/~jorendorff/es6-draft.html#sec-array.from
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*/
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if (!Array.from) {
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Array.from = function(arrayLike /*, mapFn, thisArg */) {
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if (arrayLike == null) {
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throw new TypeError('Object is null or undefined');
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}
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// Optional args.
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var mapFn = arguments[1];
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var thisArg = arguments[2];
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var C = this;
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var items = Object(arrayLike);
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var symbolIterator = typeof Symbol === 'function'
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? Symbol.iterator
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: '@@iterator';
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var mapping = typeof mapFn === 'function';
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var usingIterator = typeof items[symbolIterator] === 'function';
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var key = 0;
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var ret;
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var value;
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if (usingIterator) {
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ret = typeof C === 'function'
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? new C()
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: [];
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var it = items[symbolIterator]();
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var next;
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while (!(next = it.next()).done) {
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value = next.value;
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if (mapping) {
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value = mapFn.call(thisArg, value, key);
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}
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ret[key] = value;
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key += 1;
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}
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ret.length = key;
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return ret;
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}
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var len = items.length;
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if (isNaN(len) || len < 0) {
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len = 0;
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}
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ret = typeof C === 'function'
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? new C(len)
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: new Array(len);
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while (key < len) {
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value = items[key];
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if (mapping) {
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value = mapFn.call(thisArg, value, key);
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}
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ret[key] = value;
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key += 1;
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}
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ret.length = key;
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return ret;
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};
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}
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