expressjsHow can I use Express.js and websockets together to create real-time applications?

Express.js and websockets can be used together to create real-time applications. Websockets enable bi-directional communication between the client and the server, allowing for real-time updates in the application. Here is an example of how to use Express.js and websockets together to create a real-time application:

// Create a websocket server
const WebSocket = require('ws');
const wss = new WebSocket.Server({ port: 8080 });

// Create Express server
const express = require('express');
const app = express();

// Create websocket handler
wss.on('connection', (ws) => {
    ws.on('message', (message) => {
        console.log(`Received message => ${message}`);
    });
    ws.send('Hello from the server!');
});

// Start Express server
app.listen(3000, () => {
    console.log('Express server listening on port 3000');
});

Output example

Received message => Hello from the client!
Express server listening on port 3000

The code above creates a websocket server on port 8080 and an Express server on port 3000. It then creates a websocket handler which logs incoming messages from the client and sends a message to the client. Finally, it starts the Express server.

Code explanation

1. const WebSocket = require('ws'); - This line imports the ws module which allows us to create a websocket server.
2. const wss = new WebSocket.Server({ port: 8080 }); - This line creates a websocket server on port 8080.
3. const express = require('express'); - This line imports the express module which allows us to create an Express server.
4. const app = express(); - This line creates an Express server.
5. wss.on('connection', (ws) => {...}); - This line creates a websocket handler which handles incoming messages from the client and sends messages to the client.
6. app.listen(3000, () => {...}); - This line starts the Express server on port 3000.

Helpful links

• Express.js
• Websockets

Edit this code on GitHub