Socket io implementation in express generator

SocketIO-Express-helper.js

/****** bin/www ******/
// After -> server.listen(port);
// Addd the following for Socket.IO
var io = require('socket.io').listen(server);
require('../custom_modules/socket-helper')(io);


/****** socket-helper.js module ******/
module.exports = function (io) { 
    io.on('connection', function(socket){
        console.log(socket.id);
        socket.on('disconnect', function(){
            console.log('user disconnected');
        });
        socket.on('chat_message', function(msg){
            console.log( msg);
            io.emit('chat_message',"-->" + msg);
        });
    });
 }