expressjsHow can I use Express.js to implement websockets in my application?
Express.js is a web application framework for Node.js that can be used to implement websockets in your application. Websockets are a protocol for bi-directional communication between a server and a client.
To use Express.js to implement websockets, you will need to install the ws
package.
npm install ws
Once the ws
package is installed, you can create a websocket server using the WebSocket.Server
class. This class takes an http.Server
instance as an argument.
const http = require('http');
const express = require('express');
const WebSocket = require('ws');
const app = express();
const server = http.createServer(app);
const wss = new WebSocket.Server({ server });
The wss
object will be an instance of WebSocket.Server
that you can use to listen for events and send messages.
To listen for events, you can use the on
method. This method takes two arguments: the name of the event and a callback function.
wss.on('connection', (ws) => {
ws.on('message', (message) => {
console.log(`Received message => ${message}`);
});
});
To send a message, you can use the send
method. This method takes a string as an argument.
wss.on('connection', (ws) => {
ws.send('Hello World!');
});
Once you've set up the websocket server, you can start the server using the listen
method.
server.listen(8080, () => {
console.log('Listening on http://localhost:8080');
});
Output example
Listening on http://localhost:8080
Helpful links
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