What's the difference between Promise.resolve().then() vs. setTimeout for Scheduling Asynchronous Tasks?

Question

In Javascript, I've ran into an example that creates a batching process via an asynchronous call with Promise.resolve().then(runDownTheQueue) in pseudocode it looks something like:

function queueEverythingUp (addMeToQueue) {
  if (queueIsEmpty) {
    Promise.resolve().then(runDownTheQueue);
  }
  addToQueue(addMeToQueue);
}

This is just a method for setting up batches to be run in a queue.

My question is, how does the use of a Promise differ from this approach to asynchronous scheduling:

function queueEverythingUp (addMeToQueue) {
  if (queueIsEmpty) {
    setTimeout(() => {runDownTheQueue()}, 0);
  }
  addToQueue(addMeToQueue);
}

In both cases it seems that the execution of running down the queue is asynchronously deferred until the queue is built up via synchronous calls to queueEverythingUp.

Is the only difference the internal workings of how Promises and setTimeouts interact with the Javascript engine?

Ref: https://stackoverflow.com/questions/38752620/promise-vs-settimeout — palaѕн, Mar 26 '18 at 15:39
Microtask vs. macrotask is what I was looking for. This is a duplicate question. Can't delete it tho... — MFave, Mar 27 '18 at 01:02
analogous question here https://stackoverflow.com/questions/38752620/promise-vs-settimeout/ , short answer https://stackoverflow.com/a/46455210/2836443 — Strider, Dec 22 '19 at 17:51

What's the difference between Promise.resolve().then() vs. setTimeout for Scheduling Asynchronous Tasks?

0 Answers0