function getDateDifference() {
  var minutes = 1000 * 60;
  var hours = minutes * 60;
  var days = hours * 24;
  var years = days * 365;
  var arvDay = document.getElementById('firstDay').value;
  var arvDayinitial = arvDay
  var arvDay = Date.parse(arvDay);
  var arvDay = new Date(arvDay).clearTime(); 
  var firstDay = arvDay/years;
  var depDay = document.getElementById('secondDay').value;
  var depDayinitialval = depDay
  var depDay = Date.parse(depDay);
  var depDay = new Date(depDay).clearTime();    
  var secondDay = depDay/years;
  var dayDiff = ((secondDay - firstDay)*52*7);
  var dayDiff = (dayDiff + 1).toFixed(0);

if (arvDayinitial!="" && depDayinitialval!="") {
  if (dayDiff > 1) {
      document.getElementById('DisplayDateDifference').innerHTML=dayDiff + " days";
      } else if (dayDiff <= 0) {
      document.getElementById('DisplayDateDifference').innerHTML='Check: arrival date is later than departure date!';
      } else {
      //document.getElementById('DisplayDateDifference').innerHTML=arvDayinitial + ' = Same day?';
      arvDayinitial = Date.parse(arvDayinitial).toString('MMMM dS')
      document.getElementById('DisplayDateDifference').innerHTML=arvDayinitial + ' = Same day?';
      }

} else {
  document.getElementById('DisplayDateDifference').innerHTML='';
  }
}