15.2.3.6-4-9.js (1342B)
1 // Copyright (c) 2012 Ecma International. All rights reserved. 2 // This code is governed by the BSD license found in the LICENSE file. 3 4 /*--- 5 info: | 6 Step 4 of defineProperty calls the [[DefineOwnProperty]] internal method 7 of O to define the property. Step 7b of [[DefineOwnProperty]] rejects if 8 current.[[Enumerable]] and desc.[[Enumerable]] are the boolean negations 9 of each other. 10 es5id: 15.2.3.6-4-9 11 description: > 12 Object.defineProperty throws TypeError when changing 13 [[Enumerable]] from true to false on non-configurable data 14 properties 15 ---*/ 16 17 var o = {}; 18 19 // create a data valued property with [[Enumerable]] explicitly set to true; 20 // all other attributes default to false. 21 var d1 = { 22 value: 101, 23 enumerable: true, 24 configurable: false 25 }; 26 Object.defineProperty(o, "foo", d1); 27 28 // now, setting enumerable to false should fail, since [[Configurable]] 29 // on the original property will be false. 30 var desc = { 31 value: 101, 32 enumerable: false 33 }; 34 assert.throws(TypeError, function() { 35 Object.defineProperty(o, "foo", desc); 36 }); 37 // the property should remain unchanged. 38 var d2 = Object.getOwnPropertyDescriptor(o, "foo"); 39 assert.sameValue(d2.value, 101, 'd2.value'); 40 assert.sameValue(d2.enumerable, true, 'd2.enumerable'); 41 assert.sameValue(d2.configurable, false, 'd2.configurable'); 42 43 reportCompare(0, 0);