Priority based task execution in JS using WebWorker

priority-based-task-execution.ts

const FastPriorityQueue = require("fastpriorityqueue");

const setZeroTimeout = (callback: any) => {
  const channel = new MessageChannel();
  channel.port1.onmessage = callback;
  channel.port2.postMessage("");
};

const queue: any = new FastPriorityQueue( (a: any, b: any) =>
  a.data.priority > b.data.priority
);
self.addEventListener("message", (message: any) => {
  queue.add(message);
  if (isProcessing) {
    return;
  }
  exec();
}, false);

let isProcessing = false;
const exec = () => {
  if (queue.isEmpty()) {
    isProcessing = false;
    return;
  }
  isProcessing = true;
  processMessage(queue.poll());
  setZeroTimeout( () => {
    exec();
  });
};

const processMessage = (message: any) => {
  // do some more CPU intensive processing
  (self as any).postMessage(...);
};