Page Monitor NodeJS - usage: node pageMonitor.js http://url.com/ 300

pageMonitor.js

var http = require('http');
var url = require("url");
var crypto = require('crypto');

if(process.argv.length != 4)
{
  console.log('Syntax ::');
  console.log('node pagemonitor.js http://my-url-to-monitor.com 300');
  console.log('with 300 the interval check (in seconds (300s = 5min)).');
  process.exit(1);
}


var urlInput = process.argv[2], interval = parseInt(process.argv[3]);
var urlRegex = new RegExp(/[-a-zA-Z0-9@:%_\+.~#?&//=]{2,256}\.[a-z]{2,4}\b(\/[-a-zA-Z0-9@:%_\+.~#?&//=]*)?/gi);

if (!urlInput.match(urlRegex))
{
  console.log("this:" + url + " is not a url");
  process.exit(1);
}

var urlParts = url.parse(urlInput, true);


if(isNaN(interval))
{
  console.log(process.argv[3] + " is not a number.");
  process.exit(1);
}

var firstDate, firstMd5;

var changementAlert = function(){
      console.log("CHANGEMENT");
      console.log('\u0007');
      process.exit(0);

};

var intervalCheck = function(){
  var optionsSec = { method: 'GET', host: urlParts.host, port: urlParts.port, path: urlParts.path };
  var requestSec = http.request(optionsSec, function(res) {
      var data = '';
      if(Date.parse(res.headers["last-modified"]) != firstDate)
        changementAlert();

      res.on('data', function(chunk) {
          data += chunk.toString();
      });
      res.on('end', function(){
        if(crypto.createHash('md5').update(data).digest('hex') != firstMd5)
          changementAlert();
      });

    }
  ).end();

};

var options = { method: 'GET', host: urlParts.host, port: urlParts.port, path: urlParts.path };
var req = http.request(options, function(res) {
    firstDate = Date.parse(res.headers["last-modified"]);
    var data = '';

    res.on('data', function(chunk) {
        data += chunk.toString();
    });
    res.on('end', function(){
      firstMd5 = crypto.createHash('md5').update(data).digest('hex');
    });

  }
);



req.on('finish', function(){
        setInterval(intervalCheck, interval);
});

req.end();