Introduction

There are a number of different scenarios where it's necessary to bundle some code separately for a different JavaScript context. Web Workers are perhaps the most popular case, however the same underlying functionality is necessary in order to bundle code for use in Service Workers, Module Workers and Worklets. Since many tools apply special handling to Web Workers, it can take time to catch up with new worker variants.

The Test

This test checks that it's possible to reuse the underlying functionality of code splitting between workers for new or custom context types, without having to wait for a new release of the build tool. Effectively, it tests that it's possible to create an entry point and obtain its bundled URL at runtime.

index.js

import workerURL from 'get-worker-url-somehow';
import { logCaps } from './utils.js';

new InterestingNewWorkerType(workerURL);
logCaps('This is index');

worker.js

import { logCaps } from './utils.js';
logCaps('This is worker');

utils.js

export function logCaps(msg) {
  console.log(msg.toUpperCase());
}

The result of bundling these modules should be two or three files: one bundle for the main thread and one for the worker thread, and ideally a shared bundle for the logCaps utility method that can be used by both bundles.