Question

我试图延伸这两个承诺：

   it('using `class X extends Promise{}` is possible', function() {
  class MyPromise extends Promise {
    constructor()
    {
      super();
    }
  };
  const mypromise = new MyPromise((resolve) => resolve());

  promise
    .then(() => done())
    .catch(e => done(new Error('Expected to resolve, but failed with: ' + e)));
});

it('must call `super()` in the constructor if it wants to inherit/specialize the behavior', function() {
  class ResolvingPromise extends Promise {
    constructor() {
    super();
    }}

  return new ResolvingPromise((resolve) => resolve());
});

});

并且收到此错误：

＆＃34;构造函数承诺需要＆＃39; new＆＃39;＆＃34;

我正在使用＆＃39; new＆＃39;，那么它对我有什么要求？

Answer 1

这似乎就是答案

it('must call `super()` in the constructor if it wants to inherit/specialize the behavior', function() {
      class ResolvingPromise extends Promise {
        constructor(resolve) {
          super(resolve);
        }
      }

      return new ResolvingPromise((resolve) => resolve());
    });

Answer 2

it('using `class X extends Promise{}` is possible', function() {
      class MyPromise extends Promise {}
      const promise = new MyPromise((resolve, reject) => {})

      promise
        .then(() => done())
        .catch(e => done(new Error('Expected to resolve, but failed with: ' + e)));
    });

通过ES6 Katas，扩展承诺

2 个答案: