tor-browser

The Tor Browser
git clone https://git.dasho.dev/tor-browser.git
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construct-newtarget.js (2891B)

      1 /* This Source Code Form is subject to the terms of the Mozilla Public
      2 * License, v. 2.0. If a copy of the MPL was not distributed with this
      3 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
      4 
      5 const GeneratorFunction = function*(){}.constructor;
      6 
      7 
      8 // Test subclassing %GeneratorFunction% works correctly.
      9 class MyGenerator extends GeneratorFunction {}
     10 
     11 var fn = new MyGenerator();
     12 assertEq(fn instanceof MyGenerator, true);
     13 assertEq(fn instanceof GeneratorFunction, true);
     14 assertEq(Object.getPrototypeOf(fn), MyGenerator.prototype);
     15 
     16 fn = Reflect.construct(MyGenerator, []);
     17 assertEq(fn instanceof MyGenerator, true);
     18 assertEq(fn instanceof GeneratorFunction, true);
     19 assertEq(Object.getPrototypeOf(fn), MyGenerator.prototype);
     20 
     21 fn = Reflect.construct(MyGenerator, [], MyGenerator);
     22 assertEq(fn instanceof MyGenerator, true);
     23 assertEq(fn instanceof GeneratorFunction, true);
     24 assertEq(Object.getPrototypeOf(fn), MyGenerator.prototype);
     25 
     26 fn = Reflect.construct(MyGenerator, [], GeneratorFunction);
     27 assertEq(fn instanceof MyGenerator, false);
     28 assertEq(fn instanceof GeneratorFunction, true);
     29 assertEq(Object.getPrototypeOf(fn), GeneratorFunction.prototype);
     30 
     31 
     32 // Set a different constructor as NewTarget.
     33 fn = Reflect.construct(MyGenerator, [], Array);
     34 assertEq(fn instanceof MyGenerator, false);
     35 assertEq(fn instanceof GeneratorFunction, false);
     36 assertEq(Object.getPrototypeOf(fn), Array.prototype);
     37 
     38 fn = Reflect.construct(GeneratorFunction, [], Array);
     39 assertEq(fn instanceof GeneratorFunction, false);
     40 assertEq(Object.getPrototypeOf(fn), Array.prototype);
     41 
     42 
     43 // The prototype defaults to %GeneratorFunctionPrototype% if null.
     44 function NewTargetNullPrototype() {}
     45 NewTargetNullPrototype.prototype = null;
     46 
     47 fn = Reflect.construct(GeneratorFunction, [], NewTargetNullPrototype);
     48 assertEq(fn instanceof GeneratorFunction, true);
     49 assertEq(Object.getPrototypeOf(fn), GeneratorFunction.prototype);
     50 
     51 fn = Reflect.construct(MyGenerator, [], NewTargetNullPrototype);
     52 assertEq(fn instanceof MyGenerator, false);
     53 assertEq(fn instanceof GeneratorFunction, true);
     54 assertEq(Object.getPrototypeOf(fn), GeneratorFunction.prototype);
     55 
     56 
     57 // "prototype" property is retrieved exactly once.
     58 var trapLog = [], getLog = [];
     59 var ProxiedConstructor = new Proxy(GeneratorFunction, new Proxy({
     60    get(target, propertyKey, receiver) {
     61        getLog.push(propertyKey);
     62        return Reflect.get(target, propertyKey, receiver);
     63    }
     64 }, {
     65    get(target, propertyKey, receiver) {
     66        trapLog.push(propertyKey);
     67        return Reflect.get(target, propertyKey, receiver);
     68    }
     69 }));
     70 
     71 fn = Reflect.construct(GeneratorFunction, [], ProxiedConstructor);
     72 assertEqArray(trapLog, ["get"]);
     73 assertEqArray(getLog, ["prototype"]);
     74 assertEq(fn instanceof GeneratorFunction, true);
     75 assertEq(Object.getPrototypeOf(fn), GeneratorFunction.prototype);
     76 
     77 
     78 if (typeof reportCompare === "function")
     79    reportCompare(0, 0);