asyncList.js

function defered() {
  const def = {};
  def.promise = new Promise((resolve, reject) => {def.resolve = resolve; def.reject = reject;});
  return def;
}

function request(url) {
  let def = defered();
  const req = new XMLHttpRequest();
  req.open("GET", "http://localhost:8000/DSC00887.JPG");
  function update(event) {
    const oldDef = def;
    def = defered();
    oldDef.resolve({ next: event.type === 'load' ? null : def.promise, event });
  }
  req.addEventListener('progress', update);
  req.addEventListener('load', update);
  req.upload.addEventListener('progress', update);
  req.upload.addEventListener('load', update);
  req.send();
  return { next: def.promise, event: null };
}

async function main() {
  let { next, event } = request();
  do {
    const value = await next;
    next = value.next;
    event = value.event;
    console.log(event);
  } while (next);
  console.log('COMPLETE')
}

main();