tor-browser

The Tor Browser
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set-mutable-binding-binding-deleted-in-get-unscopables-strict-mode.js (1024B)

      1 // Copyright (C) 2024 André Bargull. All rights reserved.
      2 // This code is governed by the BSD license found in the LICENSE file.
      3 
      4 /*---
      5 esid: sec-object-environment-records-setmutablebinding-n-v-s
      6 description: >
      7  Binding deleted when retrieving unscopables.
      8 info: |
      9  9.1.1.2.5 SetMutableBinding ( N, V, S )
     10 
     11  1. Let bindingObject be envRec.[[BindingObject]].
     12  2. Let stillExists be ? HasProperty(bindingObject, N).
     13  3. If stillExists is false and S is true, throw a ReferenceError exception.
     14  ...
     15 
     16 flags: [noStrict]
     17 features: [Symbol.unscopables]
     18 ---*/
     19 
     20 var unscopablesCalled = 0;
     21 
     22 var env = {
     23  binding: 0,
     24  get [Symbol.unscopables]() {
     25    unscopablesCalled++;
     26    delete env.binding;
     27    return null;
     28  }
     29 };
     30 
     31 with (env) {
     32  assert.throws(ReferenceError, function() {
     33    "use strict";
     34    binding = 123;
     35  });
     36 }
     37 
     38 assert.sameValue(unscopablesCalled, 1, "get [Symbol.unscopables] called once");
     39 
     40 assert.sameValue(Object.getOwnPropertyDescriptor(env, "binding"), undefined, "binding deleted");
     41 
     42 reportCompare(0, 0);