tor-browser

The Tor Browser
git clone https://git.dasho.dev/tor-browser.git
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constructor-this-tdz-during-initializers.js (1135B)

      1 // Copyright (C) 2018 Kevin Gibbons. All rights reserved.
      2 // This code is governed by the BSD license found in the LICENSE file.
      3 /*---
      4 esid: sec-super-keyword-runtime-semantics-evaluation
      5 description: >
      6    `this` is bound in the constructor of derived classes immediately before running initializers
      7 info: |
      8    [...]
      9    6. Let result be ? Construct(func, argList, newTarget).
     10    [...]
     11    10. Perform ? thisER.BindThisValue(result).
     12    11. Perform ? InitializeInstanceFields(result, F).
     13    [...]
     14 features: [class-fields-public]
     15 ---*/
     16 
     17 
     18 var probeCtorThis;
     19 var thisDuringField;
     20 var thisFromProbe;
     21 var thisDuringCtor;
     22 
     23 class Base {
     24  constructor() {
     25    assert.throws(ReferenceError, probeCtorThis);
     26  }
     27 }
     28 
     29 var C = class extends Base {
     30  field = (thisDuringField = this, thisFromProbe = probeCtorThis());
     31  constructor() {
     32    probeCtorThis = () => this;
     33    assert.throws(ReferenceError, probeCtorThis);
     34    super();
     35    thisDuringCtor = this;
     36  }
     37 };
     38 
     39 var instance = new C();
     40 
     41 assert.sameValue(thisDuringField, instance);
     42 assert.sameValue(thisFromProbe, instance);
     43 assert.sameValue(thisDuringCtor, instance);
     44 
     45 reportCompare(0, 0);