Risolto

codice:
 var DataScadenza = document.Qform.DataT1.value.split("/"); 
 var newDate  = new Date(DataScadenza[2],DataScadenza[1]-1,DataScadenza[0]);
 var currDate = new Date();   
 
 difference = (newDate - currDate);
 days = Math.round(difference/86400000);

 if ( (difference) > (1000 * 60 * 60 * 360) || (difference) < (1000 * 60 * 60) )     
      {          
      alert(newDate + '\n' + currDate + '\n' + days);      
      return;          
      }