Comlink example for Node.js with TypeScript

main.ts

/**
 * https://github.com/GoogleChromeLabs/comlink/blob/master/docs/examples/06-node-example/main.mjs
 * https://github.com/GoogleChromeLabs/comlink/issues/476#issuecomment-642765445
 * esModuleInterop to true in tsconfig.json compilerOptions.
 */
import { Worker } from 'worker_threads';
import * as comlink from 'comlink';
import nodeEndpoint from 'comlink/dist/umd/node-adapter';
import { cpus } from 'os';

import type { Api } from './worker';

const workers = new Set<comlink.Remote<Api>>();

function startWorkers() {
  const count = cpus().length;

  for (let i = 0; i < count; i += 1) {
    const worker = new Worker(`${__dirname}/worker.js`, { workerData: { idx: i } });
    workers.add(comlink.wrap<Api>(nodeEndpoint(worker)));
  }
}

function stopWorkers() {
  workers.forEach((worker) => worker.exit());
}

(async () => {
  startWorkers();

  const promises = [];
  for (const worker of workers) {
    promises.push(worker.calc(Date.now()));
  }

  console.time('comlink');
  console.log(await Promise.all(promises));
  console.timeEnd('comlink');

  stopWorkers();
})();

worker.ts

/**
 * https://github.com/GoogleChromeLabs/comlink/blob/master/docs/examples/06-node-example/worker.mjs
 */
import { parentPort, workerData } from 'worker_threads';
import * as comlink from 'comlink';
import nodeEndpoint from 'comlink/dist/umd/node-adapter';

if (!parentPort) {
  throw new Error('InvalidWorker');
}

export class Api {
  private initData = workerData;

  public calc(time: number): number {
    const label = `${this.initData.idx}. calc-${time}`;

    console.time(label);
    let n = 0;
    for (let i = 0; i <= 1000000000; i += 1) {
      n += Number(i);
    }
    console.timeEnd(label);

    return this.initData.idx * n + time;
  }

  public exit(): void {
    return process.exit();
  }
}

comlink.expose(new Api(), nodeEndpoint(parentPort));

👍 Thank you, setting the type wasn't clear to me from the docs