Async iterator that yields each promises results in resolve order

promises-iter.js

async function* promisesIter(promises) {
  promises = [...promises];
  const buffer = [];
  for (promise of promises) {
    promise.then(result => {
      promises.splice(promises.indexOf(promise), 1);
      buffer.push(result);
    });
  }
  while (promises.length === 0 || await Promise.race(promises).then(() => true)) {
    while (buffer.length > 0) yield buffer.pop();
    if (promises.length === 0) break;
    await new Promise(res => setTimeout(res, 0));
  }
}

This is so freaking awesome, I made a copy with comments and some renaming, etc., but also added an inline test.

https://gist.github.com/dfkaye/1260506378b71dac62596acc54174a97

@reu I found a couple things that needed changing:

1. the yield should use shift() instead push() so the buffer acts like a queue not a stack, and
2. the await timeout should appear as the first not the last step in the loop (else not all results are buffered).

I’ve updated my gist with more detail, and I promise to stop bugging you.