Demo Websocket with NodeJS & Socket.io (Server-side)

server.js

var io = require('socket.io');
var socket = io.listen(6666);
socket.sockets.on('connection',function(socket){
	socket.on('message', function(expr){
		console.log('Received expression from client ',expr);
		try{
			socket.send(eval(expr));
		} catch(err){
			socket.emit("error",err.message);
		}
	});
	socket.on('disconnect', function(){
		console.log('Disconnected');
	});
});