// Copyright (c) 2012 Ecma International. All rights reserved. // This code is governed by the BSD license found in the LICENSE file. /*--- esid: sec-array.prototype.map es5id: 15.4.4.19-9-11 description: > Array.prototype.map - returns an empty array if 'length' is 0 (subclassed Array, length overridden with obj w/o valueOf (toString)) ---*/ function Foo() { } Foo.prototype = [1, 2, 3]; var f = new Foo(); var o = { toString: function () { return '0'; } }; f.length = o; // objects inherit the default valueOf method of the Object object; // that simply returns the itself. Since the default valueOf() method // does not return a primitive value, ES next tries to convert the object // to a number by calling its toString() method and converting the // resulting string to a number. function cb() { } var a = Array.prototype.map.call(f, cb); assert(Array.isArray(a), 'Array.isArray(a) !== true'); assert.sameValue(a.length, 0, 'a.length');