Worker Thread

Introduction

The worker thread listens for messages from the main thread, processes data, and sends results back.

Receiving and Sending

// 📁 worker.js
// Receive data from main thread
onmessage = (event) => {
  const { numbers } = event.data;

  // Perform heavy computation
  const result = numbers.map(n => expensiveComputation(n));

  // Send result back to main thread
  postMessage(result);
};

function expensiveComputation(n) {
  let result = 0;
  for (let i = 0; i < 1000000; i++) {
    result += Math.sqrt(n * i);
  }
  return result;
}

Worker Self Reference

// In a worker, `self` refers to the worker's global scope
self.onmessage = (event) => {
  self.postMessage(processData(event.data));
};

// self.close() terminates the worker from within
self.close();

Summary

Workers receive data via onmessage event
Workers send results via postMessage(data)
Use self to refer to the worker’s global scope
self.close() terminates the worker from inside

Worker Thread

Worker Thread

Introduction

Receiving and Sending

Worker Self Reference

Summary

Further Reading