Why real-time matters in Node.js - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a simple Node.js server that listens on port 3000.

Node.js

const http = require('http');
const server = http.createServer((req, res) => {
  res.end('Hello World');
});
server.listen([1]);

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

A3000

B8080

C5000

D80

Attempts:

3 left

💡 Hint

Common Mistakes

Using port 80 without proper permissions.

Choosing a port number that is already in use.

The server listens on port 3000, which is a common port for development servers.

2fill in blank

medium

Complete the code to import the 'ws' library for WebSocket support.

Node.js

const WebSocket = [1]('ws');

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

Aimport

Bfetch

Crequire

Dconnect

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'import' without enabling ES modules.

Using 'fetch' which is for HTTP requests.

In Node.js, 'require' is used to import modules like 'ws'.

3fill in blank

hard

Fix the error in the WebSocket server code by completing the missing method.

Node.js

const wss = new WebSocket.Server({ port: 8080 });
wss.on('connection', function connection(ws) {
  ws.[1]('Welcome to the server!');
});

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

Awrite

Bsend

Cemit

Dpush

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'write' which is for streams.

Using 'emit' which triggers events.

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

4fill in blank

hard

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

Node.js

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

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

Aclient

Bws

Csocket

Dconnection

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names inconsistently.

Using undefined variable names.

The variable 'ws' is commonly used to represent each WebSocket client in the loop.

5fill in blank

hard

Fill all three blanks to set up a real-time message event handler.

Node.js

wss.on('connection', function connection(ws) {
  ws.on('[1]', function incoming([2]) {
    console.log('Received: %s', [3]);
  });
});

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

Amessage

Bmsg

Dconnect

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'connect' instead of 'message' event.

Using different names for the parameter and logged variable.

The 'message' event listens for incoming messages, 'msg' is the parameter holding the message data.