1 | 'use strict';
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2 | var $ = require('../internals/export');
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3 | var toObject = require('../internals/to-object');
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4 | var lengthOfArrayLike = require('../internals/length-of-array-like');
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5 | var setArrayLength = require('../internals/array-set-length');
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6 | var deletePropertyOrThrow = require('../internals/delete-property-or-throw');
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7 | var doesNotExceedSafeInteger = require('../internals/does-not-exceed-safe-integer');
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8 |
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9 |
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10 | var INCORRECT_RESULT = [].unshift(0) !== 1;
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11 |
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12 |
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13 | var properErrorOnNonWritableLength = function () {
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14 | try {
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15 |
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16 | Object.defineProperty([], 'length', { writable: false }).unshift();
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17 | } catch (error) {
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18 | return error instanceof TypeError;
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19 | }
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20 | };
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21 |
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22 | var FORCED = INCORRECT_RESULT || !properErrorOnNonWritableLength();
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23 |
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24 |
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25 |
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26 | $({ target: 'Array', proto: true, arity: 1, forced: FORCED }, {
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27 |
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28 | unshift: function unshift(item) {
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29 | var O = toObject(this);
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30 | var len = lengthOfArrayLike(O);
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31 | var argCount = arguments.length;
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32 | if (argCount) {
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33 | doesNotExceedSafeInteger(len + argCount);
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34 | var k = len;
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35 | while (k--) {
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36 | var to = k + argCount;
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37 | if (k in O) O[to] = O[k];
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38 | else deletePropertyOrThrow(O, to);
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39 | }
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40 | for (var j = 0; j < argCount; j++) {
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41 | O[j] = arguments[j];
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42 | }
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43 | } return setArrayLength(O, len + argCount);
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44 | }
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45 | });
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