How to use WebSockets in JavaScript
WebSocket protocol is used for persistent communication of data between the server and client. We can transfer data in both directions in the form of a "packet" using HTTP and HTTPS protocols.
Installing ws using npm
To use WebSockets in JavaScript, we have to install the ws package by using npm.
$ npm i ws
Import/require WebSocket
Before using WebSockets in JavaScript, we must import it into our file or project. To do this, we can use both import and require depending upon our application.
Using 'import'
import Websocket from 'ws'
Using 'require'
const WebSocket = require(ws);
Simple server-client example
In this example, we are simply making a messaging app. When we run the code below, we will see a simple messaging app.
const WebSocket = require(`ws`);
const wss = new WebSocket(`ws://localhost:3000`);
wss.onmessage = function (e) {
console.log("I'm client")
let message = JSON.parse(e.data);
console.log(message);
};
Simple messaging app
Explanation of server.js
- Line 1: We import the
wspackage. - Line 2: We assign the communication port on 3000.
- Line 4: We make a function using
ws.on. - Line 5: We specify the message ("I'm server"), which will be displayed.
- Line 6: We create a message "Connection Established!. M2C!"
- Line 7: We send the message to the client.
Explanation of client.js
- Line 1: We import the
wspackage. - Line 2: We assign the communication port on 3000.
- Line 4: We make a function using
ws.onmessagethat will receive the message. - Line 5: We display "I'm client" on the console.
- Line 6: We receive the message in the
messagevariable. - Line 7: We display the received message on the console.
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