iteratePromises.js

// per https://twitter.com/yoshuawuyts/status/1494119486429007879
// "In JavaScript, is there a function which takes N Promises, and returns an asyncIterator which yields N resolved values?"

let promises = Array.from({length: 10}, (n, i) => {
  return new Promise(cb => setTimeout(cb, Math.random() * 1e3, i))
})

let iterator = iteratePromises(promises)
for await (let value of iterator) console.log(value)

function iteratePromises(promises) {
  let done = false
  let queue = []
  let resolve
  let promise

  defer()

  for (let p of promises) p.then(write)
  Promise.all(promises).then(end)

  return read()

  function defer() {
    promise = new Promise(r => resolve = r)
  }

  async function* read() {
    await promise
    yield* queue.splice(0)
    if (!done) yield* read()
  }

  function write(value) {
    queue.push(value)
    resolve()
    defer()
  }

  function end() {
    done = true
    resolve()
  }
}