tor-browser

The Tor Browser
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superclass-emulates-undefined.js (913B)

      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 esid: sec-runtime-semantics-classdefinitionevaluation
      5 description: >
      6  [[IsHTMLDDA]] object as superclass: `null` check uses strict equality.
      7  IsConstructor check is performed before "prototype" lookup.
      8 info: |
      9  ClassDefinitionEvaluation
     10 
     11  [...]
     12  5. Else,
     13    [...]
     14    d. Let superclass be ? GetValue(superclassRef).
     15    e. If superclass is null, then
     16      [...]
     17    f. Else if IsConstructor(superclass) is false, throw a TypeError exception.
     18 features: [class, IsHTMLDDA]
     19 ---*/
     20 
     21 var superclass = $262.IsHTMLDDA;
     22 var prototypeGets = 0;
     23 Object.defineProperty(superclass, "prototype", {
     24  get: function() {
     25    prototypeGets += 1;
     26  },
     27 });
     28 
     29 assert.throws(TypeError, function() {
     30  class C extends superclass {}
     31 });
     32 
     33 assert.sameValue(prototypeGets, 0);
     34 
     35 reportCompare(0, 0);