queue.js

const queueIfRunning = originalFn => {
  let queuedCall;
  let isRunning;

  const runner = async (...originalArgs) => {
    // If currently running, queue the next run
    if (isRunning) {
      queuedCall = originalArgs;
    } else {
      isRunning = true;
      await originalFn(...originalArgs);
      isRunning = false;

      // After the async method finishes, check if someone else is in the
      // queue, and if so, kick off another call
      if (queuedCall) {
        console.log('draining queue!');
        const queuedArgs = queuedCall;
        queuedCall = null;
        await runner(...queuedArgs);
      }
    }
  };

  return runner;
};