tor-browser

The Tor Browser
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trap-is-undefined-target-is-proxy.js (1227B)

      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-isextensible
      6 description: >
      7  If "isExtensible" trap is null or undefined, [[IsExtensible]] call is
      8  properly forwarded to [[ProxyTarget]] (which is also a Proxy object).
      9 info: |
     10  [[IsExtensible]] ( )
     11 
     12  [...]
     13  4. Let target be O.[[ProxyTarget]].
     14  5. Let trap be ? GetMethod(handler, "isExtensible").
     15  6. If trap is undefined, then
     16    a. Return ? IsExtensible(target).
     17 
     18  IsExtensible ( O )
     19 
     20  1. Assert: Type(O) is Object.
     21  2. Return ? O.[[IsExtensible]]().
     22 
     23  [[IsExtensible]] ( )
     24 
     25  [...]
     26  7. Let booleanTrapResult be ! ToBoolean(? Call(trap, handler, « target »)).
     27  [...]
     28  10. Return booleanTrapResult.
     29 features: [Proxy]
     30 ---*/
     31 
     32 var array = [];
     33 var arrayExtensible = true;
     34 var arrayTarget = new Proxy(array, {
     35  isExtensible: function() {
     36    return arrayExtensible;
     37  },
     38 });
     39 
     40 var arrayProxy = new Proxy(arrayTarget, {
     41  isExtensible: undefined,
     42 });
     43 
     44 assert(Object.isExtensible(arrayProxy));
     45 
     46 Object.preventExtensions(array);
     47 arrayExtensible = false;
     48 
     49 assert(!Object.isExtensible(arrayProxy));
     50 
     51 reportCompare(0, 0);