Introduction

Socket.io is a powerful library that enables real-time bidirectional communication between a web client and a server. This means you can build applications where data is exchanged instantly, without the need for constant polling. In this blog series, we'll explore how to use Socket.io to create a basic but functional chat application.

Setting up the Project

1. Project Setup

Start by creating a new directory for your project and navigating to it in your terminal. Then, initialize a Node.js project using npm:

2. Install Dependencies

Install the necessary dependencies using npm:

The Server-Side Implementation

1. Setting up the Server

Create a new file named index.js in your project directory. Paste the following code into the file:

        
        const express = require('express');
        const app = express();
        const http = require('http').createServer(app);
        const io = require('socket.io')(http);

        const port = process.env.PORT || 3000;

        app.get('/', (req, res) => {
          res.sendFile(__dirname + '/index.html');
        });

        io.on('connection', (socket) => {
          console.log('A user connected');

          socket.on('chat message', (msg) => {
            io.emit('chat message', msg);
          });

          socket.on('disconnect', () => {
            console.log('A user disconnected');
          });
        });

        http.listen(port, () => {
          console.log(`Server listening on port ${port}`);
        });
        
        

2. Explanation

This code sets up a simple Express server and initializes Socket.io. The server serves a basic HTML file and handles incoming socket connections:

• 'connection' event: This event is triggered when a new client connects to the server.
• 'chat message' event: This event is emitted by the client when a user sends a message. The server broadcasts this message to all connected clients.
• 'disconnect' event: This event is triggered when a client disconnects from the server.

The Client-Side Implementation

1. Creating the HTML

Create a new file named index.html in your project directory. Add the following HTML code: