Thanks @export-mike

Event queue sketch

function sync(queue) {
 // do some async operation
}

function syncFail(failedEvents, queue) {
 failedEvents.forEach(e => queue.enqueue(e));

 queue.set([...failedEvents, queue]);
}

function syncSuccess() {
 // we don't need to do anything all good!
}

// queue.js
let _queue = [];
export const enqueue = (event) => {
 _queue.push(event);
};

export const dequeue = () => {
 return _queue.pop();
}

export const dequeueAll = () => {
 const oldQueue = _queue;
 _queue = [];
 return oldQueue;
}

// main.js
import * as queue from './queue'

main() {
 setTimeout(() => {
   const batchOfEvents = queue.dequeueAll();
   sync(batchOfEvents)
   .then(() => syncSuccess())
   .catch(() => syncFail(batchOfEvents, queue));
 }, TIMEOUT);
}

onEvent(event) {
 queue.enqueue(event);
}