从事件发射器创建生成器

Question

I have a function that does something asynchronously, eg,

const doSomething = () => {
  request(url)
  .pipe(hasher)
  .on('finish', () => {
    // "return" only here
    return hasher.read();
  });
});

I would now like to "wait" in the function until hasher.read() can be returned instead of returning early with undefined (which is what the above variant does).

Ideally, I'd use doSomething as

const out = yield doSomething();

Any hints?

Answer 1

What about using deferred:

const q = require('q');

const doSomething = () => {
  const d = q.defer();

  request(url)
  .pipe(hasher)
  .on('finish', () => {
    // "return" only here
    d.resolve(hasher.read());
  });

  return d.promise;
});

Then you can handle it as a promise and use yield .