es.array.unshift.js
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es.array.unshift.js
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	'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');

	// IE8-
	var INCORRECT_RESULT = [].unshift(0) !== 1;

	// V8 ~ Chrome < 71 and Safari <= 15.4, FF < 23 throws InternalError
	var SILENT_ON_NON_WRITABLE_LENGTH = !function () {
	try {
	// eslint-disable-next-line es/no-object-defineproperty -- safe
	Object.defineProperty([], 'length', { writable: false }).unshift();
	} catch (error) {
	return error instanceof TypeError;
	}
	}();

	// `Array.prototype.unshift` method
	// https://tc39.es/ecma262/#sec-array.prototype.unshift
	$({ target: 'Array', proto: true, arity: 1, forced: INCORRECT_RESULT \|\| SILENT_ON_NON_WRITABLE_LENGTH }, {
	// eslint-disable-next-line no-unused-vars -- required for `.length`
	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);
	}
	});