如果(像我一样)你不喜欢增强本地实例，也不笨重”。承诺“属性……但是如果你喜欢代理和破坏类，那么这个是给你的:

class GroovyPromise {
  constructor() {
    return new Proxy(new Promise((resolve, reject) => {
      this.resolve = resolve;
      this.reject = reject;
    }), {
      get: (target, prop) =>
        this[prop] || target[prop].bind(target),
    });
  }
}

这样用:

const groovypromise = new GroovyPromise();
setTimeout(() => groovypromise.resolve('groovy'), 1000);
console.log(await groovypromise);

当然，你也可以将类重命名为“Deferred”

如何创建一个函数劫持拒绝并返回它?

function createRejectablePromise(handler) {
  let _reject;

  const promise = new Promise((resolve, reject) => {
    _reject = reject;

    handler(resolve, reject);
  })

  promise.reject = _reject;
  return promise;
}

// Usage
const { reject } = createRejectablePromise((resolve) => {
  setTimeout(() => {
    console.log('resolved')
    resolve();
  }, 2000)

});

reject();

helper方法可以减轻这种额外的开销，并给您同样的jQuery感觉。

function Deferred() {
    let resolve;
    let reject;
    const promise = new Promise((res, rej) => {
        resolve = res;
        reject = rej;
    });
    return { promise, resolve, reject };
}

用法是

const { promise, resolve, reject } = Deferred();
displayConfirmationDialog({
    confirm: resolve,
    cancel: reject
});
return promise;

它类似于jQuery

const dfd = $.Deferred();
displayConfirmationDialog({
    confirm: dfd.resolve,
    cancel: dfd.reject
});
return dfd.promise();

不过，在用例中，这种简单的本机语法就可以了

return new Promise((resolve, reject) => {
    displayConfirmationDialog({
        confirm: resolve,
        cancel: reject
    });
});

因为我没有找到我想要的东西，所以当我以这个问题结束时，我将分享我真正想要实现的东西。

场景:我有3个不同的API，具有相同的可能响应，因此我想在一个函数中处理承诺的完成和错误处理。这就是我所做的:

创建一个处理器函数:

  private handleHttpPromise = (promise: Promise<any>) => {
    promise
      .then((response: any) => {
        // do something with the response
        console.log(response);
      })
      .catch((error) => {
        // do something with the error
        console.log(error);
      });
  };

将承诺发送给创建的处理程序

  switch (method) {
    case 'get': {
      this.handleHttpPromise(apiService.get(url));
      break;
    }
    case 'post': {
      if (jsonData) {
        this.handleHttpPromise(apiService.post(url, jsonData));
      }
      break;
    }
    // (...)
  }

我已经整理了一个完成这项工作的要点:https://gist.github.com/thiagoh/c24310b562d50a14f3e7602a82b4ef13

以下是你应该如何使用它:

import ExternalizedPromiseCreator from '../externalized-promise';

describe('ExternalizedPromise', () => {
  let fn: jest.Mock;
  let deferredFn: jest.Mock;
  let neverCalledFn: jest.Mock;
  beforeEach(() => {
    fn = jest.fn();
    deferredFn = jest.fn();
    neverCalledFn = jest.fn();
  });

  it('resolve should resolve the promise', done => {
    const externalizedPromise = ExternalizedPromiseCreator.create(() => fn());

    externalizedPromise
      .promise
      .then(() => deferredFn())
      .catch(() => neverCalledFn())
      .then(() => {
        expect(deferredFn).toHaveBeenCalled();
        expect(neverCalledFn).not.toHaveBeenCalled();
        done();
      });

    expect(fn).toHaveBeenCalled();
    expect(neverCalledFn).not.toHaveBeenCalled();
    expect(deferredFn).not.toHaveBeenCalled();

    externalizedPromise.resolve();
  });
  ...
});

简单:

var promiseResolve, promiseReject;

var promise = new Promise(function(resolve, reject){
  promiseResolve = resolve;
  promiseReject = reject;
});

promiseResolve();