poll.js

export function poll(delay, cb, first = true) {
  let lastCb = Promise.resolve()
  let timeoutId = null
  let off = false

  if (first) {
    handleCallback()
  } else {
    done()
  }

  function done() {
    if (off) return
    timeoutId = setTimeout(handleCallback, delay)
  }

  function handleCallback() {
    lastCb = cb(done)
  }

  return () => {
    clearTimeout(timeoutId)
    off = true
    return lastCb || Promise.resolve()
  }
}