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43 lines
1.5 KiB
43 lines
1.5 KiB
2 years ago
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'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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