// 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.lastindexof description: > Array.prototype.lastIndexOf returns -1 if 'length' is 0 ( length is object overridden with obj w/o valueOf (toString)) ---*/ foo.prototype = new Array(1, 2, 3); function foo() {} 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. var i = Array.prototype.lastIndexOf.call({ length: { toString: function() { return '0'; } } }, 1); assert.sameValue(i, -1, 'i'); reportCompare(0, 0);