// Copyright 2014 the V8 project authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. "use strict"; var num = new Number(true) // Number wrapper objects are not concat-spreadable by default assertEquals([num], [].concat(num)); // Number wrapper objects may be individually concat-spreadable num[Symbol.isConcatSpreadable] = true; num.length = 3; num[0] = 1, num[1] = 2, num[2] = 3; assertEquals([1, 2, 3], [].concat(num)); Number.prototype[Symbol.isConcatSpreadable] = true; // Number wrapper objects may be concat-spreadable assertEquals([], [].concat(new Number(123))); Number.prototype[0] = 1; Number.prototype[1] = 2; Number.prototype[2] = 3; Number.prototype.length = 3; assertEquals([1,2,3], [].concat(new Number(123))); // Number values are never concat-spreadable assertEquals([true], [].concat(true));