Web Workers

As of webpack 5, you can use Web Workers without worker-loader.

Syntax

new Worker(new URL('./worker.js', import.meta.url));

The syntax was chosen to allow running code without bundler, it is also available in native ECMAScript modules in the browser.

Example

src/index.js

const worker = new Worker(new URL('./deep-thought.js', import.meta.url));
worker.postMessage({
  question:
    'The Answer to the Ultimate Question of Life, The Universe, and Everything.',
});
worker.onmessage = ({ data: { answer } }) => {
  console.log(answer);
};

src/deep-thought.js

self.onmessage = ({ data: { question } }) => {
  self.postMessage({
    answer: 42,
  });
};

Node.js

Similar syntax is supported in Node.js (>= 12.17.0):

import { Worker } from 'worker_threads';

new Worker(new URL('./worker.js', import.meta.url));

Note that this is only available in ESM. Worker in CommonJS syntax is not supported by either webpack or Node.js.