socket.io Getting started with socket.io Installation or Setup

Example

First, install socket.io module in node.js application.

npm install socket.io --save

Basic HTTP Setup

The following example attaches socket.io to a plain node.js HTTP server listening on port 3000.

var server = require('http').createServer();

var io = require('socket.io')(server);

io.on('connection', function(socket){

  console.log('user connected with socketId '+socket.id);

  socket.on('event', function(data){
      console.log('event fired');
  });

  socket.on('disconnect', function(){
      console.log('user disconnected');
  });

});

server.listen(3000);

Setup with Express

Express app can be passed to http server which will be attached to socket.io.

var app = require('express')();                   //express app
var server = require('http').createServer(app);   //passed to http server
var io = require('socket.io')(server);            //http server passed to socket.io

io.on('connection', function(){

  console.log('user connected with socketId '+socket.id);

  socket.on('event', function(data){
      console.log('event fired');
  });

  socket.on('disconnect', function(){
      console.log('user disconnected');
  });

});

server.listen(3000);

Client Side Setup

Check the Hello World example above for the client side implementation.