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 35 function F() {}; 36 F.prototype = Number; 37 38 var 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. 42 var f = new F(); 43 assertEquals(original_number_max, f.MAX_VALUE); 44 f.MAX_VALUE = 42; 45 assertEquals(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. 49 f = new F(); 50 with (f) { 51 MAX_VALUE = 42; 52 } 53 assertEquals(original_number_max, f.MAX_VALUE); 54 55 // Assignment to read-only property on the object itself is ignored. 56 Number.MAX_VALUE = 42; 57 assertEquals(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
