trap-is-undefined-target-is-proxy.js (1316B)
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-set-p-v-receiver 6 description: > 7 If "set" trap is null or undefined, [[Set]] call is properly 8 forwarded to [[ProxyTarget]] (which is also a Proxy object). 9 info: | 10 [[Set]] ( P, V, Receiver ) 11 12 [...] 13 5. Let target be O.[[ProxyTarget]]. 14 6. Let trap be ? GetMethod(handler, "set"). 15 7. If trap is undefined, then 16 a. Return ? target.[[Set]](P, V, Receiver). 17 features: [Proxy, Reflect] 18 ---*/ 19 20 var func = function() {}; 21 var funcTarget = new Proxy(func, {}); 22 var funcProxy = new Proxy(funcTarget, { 23 set: undefined, 24 }); 25 26 assert(Reflect.set(funcProxy, "prototype", null)); 27 assert.sameValue(func.prototype, null); 28 29 assert(!Reflect.set(funcProxy, "length", 2)); 30 assert.throws(TypeError, function() { 31 "use strict"; 32 funcProxy.name = "foo"; 33 }); 34 35 36 var trapCalls = 0; 37 var target = new Proxy({}, { 38 set: function(_target, key) { 39 trapCalls++; 40 return key === "foo"; 41 }, 42 }); 43 44 var proxy = new Proxy(target, { 45 set: undefined, 46 }); 47 48 assert(Reflect.set(Object.create(proxy), "foo", 1)); 49 assert.sameValue(trapCalls, 1); 50 51 assert(!Reflect.set(proxy, "bar", 2)); 52 assert.sameValue(trapCalls, 2); 53 54 reportCompare(0, 0);