Why worker threads matter in Node.js - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a new worker thread.

Node.js

const { Worker } = require('worker_threads');
const worker = new [1]('./worker.js');

Drag options to blanks, or click blank then click option'

AWorker

BChild

CProcess

DThread

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'Thread' or 'Process' instead of 'Worker'.

Confusing worker threads with child processes.

The Worker class is used to create new worker threads in Node.js.

2fill in blank

medium

Complete the code to listen for messages from a worker thread.

Node.js

worker.on('[1]', (message) => {
  console.log('Received:', message);
});

Drag options to blanks, or click blank then click option'

Adata

Bmessage

Csend

Dreceive

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'send' or 'receive' which are not event names.

Using 'data' which is not the correct event for worker messages.

The 'message' event is emitted when a worker thread sends data back.

3fill in blank

hard

Fix the error in the code to properly terminate a worker thread.

Node.js

worker.[1]();

Drag options to blanks, or click blank then click option'

Astop

Bclose

Cterminate

Dend

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'stop' or 'end' which do not exist on worker objects.

Using 'close' which is not a method for worker termination.

The terminate() method stops the worker thread immediately.

4fill in blank

hard

Fill both blanks to send a message from the main thread to the worker.

Node.js

worker.[1]([2]);

Drag options to blanks, or click blank then click option'

ApostMessage

Bsend

C'Hello, worker!'

Dmessage

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'send' instead of 'postMessage'.

Not passing a message or passing an event name instead.

Use postMessage to send data to the worker thread. The message can be any value, here a string.

5fill in blank

hard

Fill all three blanks to create a worker that runs a function from a file and handle its exit event.

Node.js

const worker = new Worker('./task.js', { [1]: true });
worker.on('[2]', (code) => {
  console.log('Worker exited with code', [3]);
});

Drag options to blanks, or click blank then click option'

Aeval

Bexit

Ccode

DrunInNewContext

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'runInNewContext' instead of 'eval'.

Listening to 'close' instead of 'exit' event.

Logging a wrong variable instead of the exit code.

Setting eval: true allows the worker to run code passed as a string. The exit event fires when the worker stops, providing the exit code.