WebSocket protocol concept in Node.js - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a WebSocket server that listens on port 8080.

Node.js

import { WebSocketServer } from 'ws';
const wss = new WebSocketServer({ port: [1] });

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

A3000

B443

C8080

D80

Attempts:

3 left

💡 Hint

Common Mistakes

Using port 80 or 443 without proper permissions or HTTPS setup.

Choosing a random port number not commonly used for WebSocket.

The WebSocket server listens on port 8080, which is a common port for WebSocket connections during development.

2fill in blank

medium

Complete the code to send a message to a connected client when the connection opens.

Node.js

wss.on('connection', function connection(ws) {
  ws.[1]('Hello Client!');
});

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

Asend

Breceive

Copen

Dconnect

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'receive' which is not a method on the WebSocket object.

Confusing event names with methods.

The send method is used to send data to the connected client over the WebSocket.

3fill in blank

hard

Fix the error in the code to properly handle incoming messages from clients.

Node.js

wss.on('connection', function connection(ws) {
  ws.on('[1]', function message(data) {
    console.log('Received:', data);
  });
});

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

Amessage

Bconnect

Csend

Dopen

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'open' or 'connect' which are not message events.

Confusing method names with event names.

The message event is emitted when the server receives data from a client.

4fill in blank

hard

Fill both blanks to broadcast a message to all connected clients.

Node.js

wss.clients.forEach(function each(client) {
  if (client.readyState === [1]) {
    client.[2]('Broadcast message');
  }
});

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

A1

B0

Csend

Dclose

Attempts:

3 left

💡 Hint

Common Mistakes

Using readyState 0 which means connecting, not open.

Using 'close' instead of 'send' to send messages.

Clients with readyState === 1 are open and ready to receive messages. Use send to send the message.

5fill in blank

hard

Fill all three blanks to close a client connection with a status code and reason.

Node.js

ws.[1]([2], '[3]');

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

Aclose

B1000

CNormal closure

Dsend

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'send' instead of 'close' to close the connection.

Using an incorrect status code or missing the reason string.

The close method closes the connection. Code 1000 means normal closure, and the string explains the reason.