/// Copyright (c) 2012 Ecma International. All rights reserved. /// Ecma International makes this code available under the terms and conditions set /// forth on http://hg.ecmascript.org/tests/test262/raw-file/tip/LICENSE (the /// "Use Terms"). Any redistribution of this code must retain the above /// copyright and this notice and otherwise comply with the Use Terms. /** * @path ch15/15.4/15.4.4/15.4.4.19/15.4.4.19-9-12.js * @description Array.prototype.map - returns an empty array if 'length' is 0 (subclassed Array, length overridden with []) */ function testcase() { function Foo() { } Foo.prototype = [1, 2, 3]; var f = new Foo(); f.length = []; // 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. // // The toString( ) method on Array converts the array elements to strings, // then returns the result of concatenating these strings, with commas in // between. An array with no elements converts to the empty string, which // converts to the number 0. If an array has a single element that is a // number n, the array converts to a string representation of n, which is // then converted back to n itself. If an array contains more than one element, // or if its one element is not a number, the array converts to NaN. function cb() { } var a = Array.prototype.map.call(f, cb); if (Array.isArray(a) && a.length === 0) { return true; } } runTestCase(testcase);