trap-is-undefined-target-is-proxy.js (1454B)
1 // Copyright (C) 2020 Alexey Shvayka. All rights reserved. 2 // This code is governed by the BSD license found in the LICENSE file. 3 4 /*--- 5 esid: sec-proxy-object-internal-methods-and-internal-slots-defineownproperty-p-desc 6 description: > 7 If "defineProperty" trap is null or undefined, [[DefineOwnProperty]] call 8 is properly forwarded to [[ProxyTarget]] (which is also a Proxy object). 9 info: | 10 [[DefineOwnProperty]] (P, Desc) 11 12 [...] 13 5. Let target be O.[[ProxyTarget]]. 14 6. Let trap be ? GetMethod(handler, "defineProperty"). 15 7. If trap is undefined, then 16 a. Return ? target.[[DefineOwnProperty]](P, Desc). 17 features: [Proxy, Reflect] 18 includes: [compareArray.js] 19 ---*/ 20 21 var array = []; 22 var arrayTarget = new Proxy(array, {}); 23 var arrayProxy = new Proxy(arrayTarget, { 24 defineProperty: undefined, 25 }); 26 27 Object.defineProperty(arrayProxy, "0", {value: 1}); 28 assert.compareArray(array, [1]); 29 30 assert.throws(TypeError, function() { 31 Object.defineProperty(arrayProxy, "length", { 32 get: function() {}, 33 }); 34 }); 35 36 37 var trapCalls = 0; 38 var target = new Proxy({}, { 39 defineProperty: function(_target, key) { 40 trapCalls++; 41 return key === "foo"; 42 }, 43 }); 44 45 var proxy = new Proxy(target, { 46 defineProperty: undefined, 47 }); 48 49 assert(Reflect.defineProperty(proxy, "foo", {})); 50 assert.sameValue(trapCalls, 1); 51 52 assert.throws(TypeError, function() { 53 Object.defineProperty(proxy, "bar", {}); 54 }); 55 assert.sameValue(trapCalls, 2); 56 57 reportCompare(0, 0);