What is a Web Worker

Web worker is a JS working in the background, without affecting the performance of the page.

Problem

When executing JS in an HTML page, the page becomes unresponsive until the script is finished.

A web worker is a JavaScript that runs in the background, independently of other scripts, without affecting the performance of the page.

• You can continue to do whatever you want: clicking, selecting things, etc., while the web worker runs in the background.

Use

w = new Worker("demo_workers.js");

w.onmessage = function(event) {
  document.getElementById("result").innerHTML = event.data;
};

w.terminate();

Bundlers like Webpack and Vite recommends passing urls resolved to relative to import.meta.url.

const myWorker = new Worker(new URL("worker.js", import.meta.url));