Node 12 worker threads

index.js

// To run: node --no-warnings --experimental-modules index.js
import {
  Worker,
  isMainThread,
  parentPort,
  workerData,
} from 'worker_threads';
import { basename } from 'path';
import { fileURLToPath } from 'url';

const scriptFilename = basename(fileURLToPath(import.meta.url));

if (isMainThread) {
  const worker = new Worker(`./${scriptFilename}`, {
    workerData: 'Hello!',
  });
  worker.on('message', (data) => {
    console.log('parent:', data);
  });
  worker.on('online', () => {
    console.log('parent: Child spotted.');
  });
  worker.on('exit', () => {
    console.log('parent: Farewell.');
  });
} else {
  console.log('child:', workerData);
  parentPort.postMessage('And hello to you!');
  console.log('child: Good bye.');
}