$(document).ready(function(){ 

   idleTime = 0; 
   setInterval(timerIncrement, 1000); 
 
   function timerIncrement(){ 
     idleTime++
     if (idleTime >= 900){ 
       doPreload(); 
       idleTime = 0; 
     } 
   } 
 
   $(this).mousemove(function(e){ 
      idleTime = 0; 
   }); 
 
   function doPreload(){ 
     alert("Your browser has been idle for 15 minutes. Your browser will be refreshed?"); 
	 document.location.href = document.location.href;
   } 
  
});