run-loop.js

_queue = [];
_isRunning = false;

async _runLoop(task) {
  let job, queue = this._queue;

  if (this._isRunning) {
    // Preempt the current tasks
    while (job = queue[0]) {
      queue.shift();
      if (job.preemptive) {
        job.run();
      }
    }
  }

  queue.push(task);

  this._isRunning = true;
  while (job = queue[0]) {
    await job.time();
    if (job === queue[0]) {
      queue.shift();
      job.run();
    }
  }
  this._isRunning = false;
}