in-memmory js funcion scheduler. Execute a promise function at a time. Very usable when receiving multiple events and want to process them one by one in order

scheduler.js

const queue = [];

async function schedule(func) {
  if (queue.length !== 0) return queue.push(func); // if another task is scheduled, push this task to the queue

  queue.push(func);
  do {
    await queue[0]();
    queue.shift();
  } while (queue.length > 0);
  return queue.length;
}