WebSocket protocol concept in Node.js - Mini Project: Build & Apply

Basic WebSocket Server with Node.js

📖 Scenario: You want to create a simple chat server that uses WebSocket protocol to allow real-time communication between clients and the server.

🎯 Goal: Build a basic WebSocket server using Node.js that accepts client connections, listens for messages, and sends back a confirmation message.

📋 What You'll Learn

Create a WebSocket server using the ws library

Set up a port number configuration variable

Listen for client connections and messages

Send a confirmation message back to the client

💡 Why This Matters

🌍 Real World

WebSocket servers are used in real-time applications like chat apps, live notifications, and online games where instant communication is needed.

💼 Career

Understanding WebSocket protocol and how to implement it with Node.js is valuable for backend developers working on interactive web applications.

1

Set up WebSocket server import and initial server

Write code to import the WebSocketServer class from the ws library and create a new WebSocket server instance called wss that listens on port 8080.

Node.js

const { WebSocketServer } = require('ws');
// Your code here

Need a hint?

Use require('ws') to import and create a new WebSocketServer with the port option set to 8080.

2

Add a port configuration variable

Create a constant variable called PORT and set it to 8080. Then update the WebSocket server instance wss to use this PORT variable instead of the hardcoded number.

Node.js

const { WebSocketServer } = require('ws');
const PORT = 8080;
const wss = new WebSocketServer({ port: PORT });
// Your code here

Need a hint?

Define const PORT = 8080; and use it in the WebSocketServer constructor.

3

Listen for client connections and messages

Add an event listener on wss for the 'connection' event with a callback function that takes a ws parameter. Inside this callback, add another event listener on ws for the 'message' event that receives a message parameter.

Node.js

const { WebSocketServer } = require('ws');
const PORT = 8080;
const wss = new WebSocketServer({ port: PORT });

wss.on('connection', (ws) => {
  // Your code here
});

Need a hint?

Use wss.on('connection', (ws) => { ... }) and inside it ws.on('message', (message) => { ... }).

4

Send confirmation message back to client

Inside the message event listener, send a message back to the client using ws.send() with the text 'Message received'.

Node.js

const { WebSocketServer } = require('ws');
const PORT = 8080;
const wss = new WebSocketServer({ port: PORT });

wss.on('connection', (ws) => {
  ws.on('message', (message) => {
    // Send confirmation message here
  });
});

Need a hint?

Use ws.send('Message received') inside the message event listener.