Inline Web Worker

Utility function to create a web worker with arguments and async iterators

Installation

npm i inline-run-on-worker

For browser, download runOnWorker.min.js.

Usage

CommonJs

const {runOnWorker} = require('inline-run-on-worker');

ES6 module (adding type: "module" to package.json)

import {runOnWorker} from 'inline-run-on-worker';

Browser

<script src="./runOnWorker.min.js"></script>

Syntax

runOnWorker(fn, args, messages);

Parameters

fn : function

A function to run on worker. All variables should be within function scope.

args : any[] = []

An array of arguments. Must be a valid input invoking structuredClone().

messages : any[iterator] = []

Either an iterable or async iterable.

Return value

The returned value is a promise resolving the return value of the function

Examples

With args

No need to handle postMessage and onmessage. Useful when args is ready.

runOnWorker((a, b) => {
    return a + b;
}, [12, 43]).then(console.log);

55

With messages

Useful when data is not ready yet (e.g.: ReadableStream read(), chunked fetch()).

let asyncGenerator = async function*() {
    for (let i = 0; i < 10; i++) {
        await new Promise(resolve => setTimeout(resolve, 100));
        yield i;
    }
};
runOnWorker(async (start, messages) => {
    let sum = start;
    for await (const message of messages) {
        sum += message;
    }
    return sum;
}, [-1], asyncGenerator()).then(console.log);

44

Why?

No

runOnWorker(() => {
    return 'why not?';
}).then(console.log);

why not?

Buggy

Load url as worker. Very limited use on webpack.

let url = new URL('./sum.js', import.meta.url).href;
runOnWorker(url, [65, 3]).then(console.log);

68