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42 lines
1.5 KiB
42 lines
1.5 KiB
'use strict'; |
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var $ = require('../internals/export'); |
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var toObject = require('../internals/to-object'); |
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var lengthOfArrayLike = require('../internals/length-of-array-like'); |
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var deletePropertyOrThrow = require('../internals/delete-property-or-throw'); |
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var doesNotExceedSafeInteger = require('../internals/does-not-exceed-safe-integer'); |
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// IE8- |
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var INCORRECT_RESULT = [].unshift(0) !== 1; |
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// V8 ~ Chrome < 71 and Safari <= 15.4, FF < 23 throws InternalError |
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var SILENT_ON_NON_WRITABLE_LENGTH = !function () { |
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try { |
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// eslint-disable-next-line es-x/no-object-defineproperty -- safe |
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Object.defineProperty([], 'length', { writable: false }).unshift(); |
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} catch (error) { |
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return error instanceof TypeError; |
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} |
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}(); |
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// `Array.prototype.unshift` method |
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// https://tc39.es/ecma262/#sec-array.prototype.unshift |
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$({ target: 'Array', proto: true, arity: 1, forced: INCORRECT_RESULT || SILENT_ON_NON_WRITABLE_LENGTH }, { |
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// eslint-disable-next-line no-unused-vars -- required for `.length` |
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unshift: function unshift(item) { |
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var O = toObject(this); |
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var len = lengthOfArrayLike(O); |
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var argCount = arguments.length; |
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if (argCount) { |
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doesNotExceedSafeInteger(len + argCount); |
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var k = len; |
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while (k--) { |
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var to = k + argCount; |
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if (k in O) O[to] = O[k]; |
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else deletePropertyOrThrow(O, to); |
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} |
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for (var j = 0; j < argCount; j++) { |
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O[j] = arguments[j]; |
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} |
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} return O.length = len + argCount; |
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} |
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});
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