function checkEmail(email) {
  var filter = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
  return !(filter.test(email));
}

function checkDate(dataarrivo) {
   var pattern = /^(\d{1,2})(\/|-)(\d{1,2})(\/|-)(\d{4})$/;
   if(pattern.test(dataarrivo))
   {
      var date_array = dataarrivo.split('/');
      var day = date_array[0];
      var month = date_array[1] - 1;
      var year = date_array[2];

      source_date = new Date(year,month,day);

      if(year != source_date.getFullYear())
      {
         return false;
      }

      if(month != source_date.getMonth())
      {
         return false;
      }

      if(day != source_date.getDate())
      {
         return false;
      }
   }
   else
   {
      return false;
   }

   return true;
}

function checkInterval(datestart, dateend) {

	var data1 = convertStringToDate(datestart);
	var data2 = convertStringToDate(dateend);
	var interval = Math.round((data2-data1) / 86400000)+1;
	return (interval > 1);
}

function convertStringToDate(dtStr) {

	var strDay=dtStr.substring(0,2)
	var strMonth=dtStr.substring(3,5)
	var strYear=dtStr.substring(6)
	var data=new Date();
	
	with (data) {
		setYear(parseInt(strYear,10));
		setDate(1);
		setMonth(0);	
		setDate(parseInt(strDay,10));
		setMonth((parseInt(strMonth,10)-1));
    setHours(0);
    setMinutes(0);
    setSeconds(0);
    setMilliseconds(0);
  }

	return data;
}