@arv/threads

Threads for JavaScript, in plain TypeScript, on Web Workers and a SharedArrayBuffer.

@arv/threads brings real threads to JavaScript, in plain TypeScript. Your code runs in parallel on Web Workers that share memory through a SharedArrayBuffer.

You also get a programming model you can reason about. Every value is owned by one thread, shared read-only, or a cell built for sharing. A checker proves that your code follows those rules.

Here's a quick taste:

import {f64, scope, SharedArray, struct, type Struct} from '@arv/threads';

const Body = struct({x: f64, y: f64, vx: f64, vy: f64, m: f64}); // Lives in shared memory.
type Body = Struct<typeof Body>;

function step(bodies: SharedArray<Body>, lo: number, hi: number) {
  for (let i = lo; i < hi; i++) bodies[i].x += bodies[i].vx; // Every thread sees the same memory.
}

export function main(threads: number) {
  const bodies = new SharedArray(Body, 800);
  scope(s => {
    for (let t = 0; t < threads; t++)
      s.spawn(
        step,
        bodies,
        Math.floor((t * 800) / threads),
        Math.floor(((t + 1) * 800) / threads),
      );
  }); // Joins every thread it started.
}

You can try it in the browser, with the compiled JavaScript side by side, in the playground. Its source is in playground/.

Where to Go Next

• Install the packages, and set up the Vite plugin, the page and the checker.
• Write, check and run a small program in the tutorial.
• Read about the model, the three kinds of values it rests on.