Function scheduleSyncCallback

docs/external/js/react-dom.development.js:11180–11194

(callback)

    return Scheduler_scheduleCallback(priorityLevel, callback, options);
  }
  function scheduleSyncCallback(callback) {
    // Push this callback into an internal queue. We'll flush these either in
    // the next tick, or earlier if something calls `flushSyncCallbackQueue`.
    if (syncQueue === null) {
      syncQueue = [callback]; // Flush the queue in the next tick, at the earliest.

      immediateQueueCallbackNode = Scheduler_scheduleCallback(Scheduler_ImmediatePriority, flushSyncCallbackQueueImpl);
    } else {
      // Push onto existing queue. Don't need to schedule a callback because
      // we already scheduled one when we created the queue.
      syncQueue.push(callback);
    }

    return fakeCallbackNode;
  }
  function cancelCallback(callbackNode) {
    if (callbackNode !== fakeCallbackNode) {
      Scheduler_cancelCallback(callbackNode);