HTML

socket io script

<script src="/socket.io/socket.io.js"></script>
<script>
  const socket = io();
</script>

socket.io node

/*The following example attaches socket.io to a plain Node.JS HTTP server listening on port 3000.*/

const server = require('http').createServer();
const io = require('socket.io')(server);
io.on('connection', client => {
  client.on('event', data => { /* … */ });
  client.on('disconnect', () => { /* … */ });
});
server.listen(3000);



//Standalone

const io = require('socket.io')();
io.on('connection', client => { ... });
io.listen(3000);
//Module syntax
import { Server } from "socket.io";
const io = new Server(server);
io.listen(3000);
                               
                               
                               
//In conjunction with Express
//Starting with 3.0, express applications have become request handler functions that you pass to http or http Server instances. You need to pass the Server to socket.io, and not the express application function. Also make sure to call .listen on the server, not the app.

const app = require('express')();
const server = require('http').createServer(app);
const io = require('socket.io')(server);
io.on('connection', () => { /* … */ });
server.listen(3000);
                               
                               
//In conjunction with Koa
//Like Express.JS, Koa works by exposing an application as a request handler function, but only by calling the callback method.

const app = require('koa')();
const server = require('http').createServer(app.callback());
const io = require('socket.io')(server);
io.on('connection', () => { /* … */ });
server.listen(3000);
                               
                               
                               
//In conjunction with Fastify
//To integrate Socket.io in your Fastify application you just need to register fastify-socket.io plugin. It will create a decorator called io.

const app = require('fastify')();
app.register(require('fastify-socket.io'));
app.io.on('connection', () => { /* … */ });
app.listen(3000);
     

socket io nodejs

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) => {
    // ...
  });
});

socket io nodejs

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');});