| 'use strict'; |
| var $ = require('../internals/export'); |
| var toObject = require('../internals/to-object'); |
| var lengthOfArrayLike = require('../internals/length-of-array-like'); |
| var setArrayLength = require('../internals/array-set-length'); |
| var deletePropertyOrThrow = require('../internals/delete-property-or-throw'); |
| var doesNotExceedSafeInteger = require('../internals/does-not-exceed-safe-integer'); |
|
|
| |
| var INCORRECT_RESULT = [].unshift(0) !== 1; |
|
|
| |
| var properErrorOnNonWritableLength = function () { |
| try { |
| |
| Object.defineProperty([], 'length', { writable: false }).unshift(); |
| } catch (error) { |
| return error instanceof TypeError; |
| } |
| }; |
|
|
| var FORCED = INCORRECT_RESULT || !properErrorOnNonWritableLength(); |
|
|
| |
| |
| $({ target: 'Array', proto: true, arity: 1, forced: FORCED }, { |
| |
| unshift: function unshift(item) { |
| var O = toObject(this); |
| var len = lengthOfArrayLike(O); |
| var argCount = arguments.length; |
| if (argCount) { |
| doesNotExceedSafeInteger(len + argCount); |
| var k = len; |
| while (k--) { |
| var to = k + argCount; |
| if (k in O) O[to] = O[k]; |
| else deletePropertyOrThrow(O, to); |
| } |
| for (var j = 0; j < argCount; j++) { |
| O[j] = arguments[j]; |
| } |
| } return setArrayLength(O, len + argCount); |
| } |
| }); |
|
|