// npm i socket.io

const http = require('http')

const express = require('express')

const socketio = require('socket.io')

​

const app = express()

const server = http.createServer(app)

const io = socketio(server)

​

const port = process.env.PORT || 3000

​

server.listen(port, () => {

  console.log(`Server is up on port ${port}!`)

})

// with npm

npm install socket.io

​

// with yarn

yarn add socket.io

// client 

npm i socket.io-client

​

// server

npm i socket.io

import { Server } from "socket.io";

​

const io = new Server(3000);

​

io.on("connection", (socket) => {

  // send a message to the client

  socket.emit("hello from server", 1, "2", { 3: Buffer.from([4]) });

​

  // receive a message from the client

  socket.on("hello from client", (...args) => {

    // ...

  });

});

const express = require('express');const app = express();const http = require('http');const server = http.createServer(app);const { Server } = require("socket.io");const io = new Server(server);app.get('/', (req, res) => {  res.sendFile(__dirname + '/index.html');});io.on('connection', (socket) => {  console.log('a user connected');});server.listen(3000, () => {  console.log('listening on *:3000');});

npm i socket.io-client /// for client side

​