1// Copyright 2009 the V8 project authors. All rights reserved. 2// Redistribution and use in source and binary forms, with or without 3// modification, are permitted provided that the following conditions are 4// met: 5// 6// * Redistributions of source code must retain the above copyright 7// notice, this list of conditions and the following disclaimer. 8// * Redistributions in binary form must reproduce the above 9// copyright notice, this list of conditions and the following 10// disclaimer in the documentation and/or other materials provided 11// with the distribution. 12// * Neither the name of Google Inc. nor the names of its 13// contributors may be used to endorse or promote products derived 14// from this software without specific prior written permission. 15// 16// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 17// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 18// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 19// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 20// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 21// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 22// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 26// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 28// According to ECMA-262, sections 8.6.2.2 and 8.6.2.3 you're not 29// allowed to override read-only properties, not even if the read-only 30// property is in the prototype chain. 31// 32// However, for compatibility with WebKit/JSC, we allow the overriding 33// of read-only properties in prototype chains. 34 35function F() {}; 36F.prototype = Number; 37 38var original_number_max = Number.MAX_VALUE; 39 40// Assignment to a property which does not exist on the object itself, 41// but is read-only in a prototype does not take effect. 42var f = new F(); 43assertEquals(original_number_max, f.MAX_VALUE); 44f.MAX_VALUE = 42; 45assertEquals(original_number_max, f.MAX_VALUE); 46 47// Assignment to a property which does not exist on the object itself, 48// but is read-only in a prototype does not take effect. 49f = new F(); 50with (f) { 51 MAX_VALUE = 42; 52} 53assertEquals(original_number_max, f.MAX_VALUE); 54 55// Assignment to read-only property on the object itself is ignored. 56Number.MAX_VALUE = 42; 57assertEquals(original_number_max, Number.MAX_VALUE); 58 59// G should be read-only on the global object and the assignment is 60// ignored. 61(function G() { 62 eval("G = 42;"); 63 assertTrue(typeof G === 'function'); 64})(); 65