app.js

//This app requires the express and serialport libraries for node. You can get them on NPM with:
//npm install express
//npm install serialport

var app = require('express')();
var http = require('http').Server(app);
var SerialPort = require("serialport").SerialPort;

var serialPort = new SerialPort("COM3", { //change port to your Arduinos port
	baudrate: 9600,
	databits: 8, // this is the default for Arduino serial communication
	parity: 'none', // this is the default for Arduino serial communication
	stopbits: 1  // this is the default for Arduino serial communication
});

serialPort.on('data', function(data) {
	console.log('data received: ' + data);
});

app.get('/', function(req, res){
  res.sendFile(__dirname + '/index.html');
});
  
app.get('/sendmsg', function(req, res){
	var message = req.query.m.replace(/~/g, " ");
	console.log("Recieved song: " + message);
	res.send("Recieved song: " + message);
	serialPort.write(message, function(err, results) {
	});
});

http.listen(3000, function(){
	console.log('listening on *:3000');
});