trap-is-null-target-is-proxy.js

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// Copyright (C) 2020 Alexey Shvayka. All rights reserved.

// This code is governed by the BSD license found in the LICENSE file.

/*---

esid: sec-proxy-object-internal-methods-and-internal-slots-set-p-v-receiver

description: >

  If "set" trap is null or undefined, [[Set]] call is properly

  forwarded to [[ProxyTarget]] (which is also a Proxy object).

info: |

  [[Set]] ( P, V, Receiver )

  [...]

  5. Let target be O.[[ProxyTarget]].

  6. Let trap be ? GetMethod(handler, "set").

  7. If trap is undefined, then

    a. Return ? target.[[Set]](P, V, Receiver).

features: [Proxy, Reflect]

includes: [compareArray.js]

---*/

var array = [1, 2, 3];

var arrayTarget = new Proxy(array, {});

var arrayProxy = new Proxy(arrayTarget, {

  set: null,

});

arrayProxy.length = 0;

assert.compareArray(array, []);

Object.preventExtensions(array);

assert(!Reflect.set(arrayProxy, "foo", 2));

assert.throws(TypeError, function() {

  "use strict";

  arrayProxy[0] = 3;

});

var string = new String("str");

var stringTarget = new Proxy(string, {});

var stringProxy = new Proxy(stringTarget, {

  set: null,

});

stringProxy[4] = 1;

assert.sameValue(string[4], 1);

assert(!Reflect.set(stringProxy, "0", "s"));

assert(!Reflect.set(stringProxy, "length", 3));

reportCompare(0, 0);