Socket.io overview in Node.js - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the Socket.io library in a Node.js server.

Node.js

const io = require('[1]');

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

Asocket.io

Bexpress

Chttp

Dfs

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'express' instead of 'socket.io'

Using 'http' which is a different Node.js module

The Socket.io library is imported using require('socket.io') in Node.js.

2fill in blank

medium

Complete the code to create a new Socket.io server attached to an HTTP server.

Node.js

const io = require('socket.io')( [1] );

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Aapp

Bhttp

Csocket

Dserver

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the Express app instead of the HTTP server

Passing the Socket.io instance itself

The Socket.io server is attached to the HTTP server instance, usually named server.

3fill in blank

hard

Fix the error in the code to listen for new client connections.

Node.js

io.on('[1]', (socket) => {
  console.log('A user connected');
});

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Aconnected

Bconnect

Cconnection

Dconnects

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'connect' which is incorrect for Socket.io

Using 'connected' which is not an event name

The correct event name to listen for new connections is 'connection'.

4fill in blank

hard

Fill both blanks to emit a message to all connected clients except the sender.

Node.js

socket.[1].emit('[2]', 'Hello everyone except me');

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Abroadcast

Bsend

Cmessage

Demit

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'socket.emit' which sends only to the sender

Using 'socket.send' which is not a method on broadcast

To send a message to all clients except the sender, use socket.broadcast.emit('message', ...).

5fill in blank

hard

Fill all three blanks to listen for a custom event and respond to the sender.

Node.js

socket.on('[1]', (data) => {
  console.log('Received:', data);
  socket.[2]('[3]', 'Got your message');
});

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

Achat message

Bemit

Creply

Dmessage

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'message' instead of 'chat message' as event name

Using 'broadcast.emit' instead of 'emit' to reply to sender

The code listens for the 'chat message' event, then uses socket.emit to send a 'reply' event back to the sender.