var cookiename="update_YOURNAME";  
     function getCookie(c_name)  
       {
       c_string=c_name+"="; 
       if(document.cookie.indexOf(c_string)==-1)
        {return "";}
       strbegin = (document.cookie.indexOf(c_string)+c_string.length);
       strend = document.cookie.indexOf(";", strbegin);
       if (strend == -1) 
        {strend = document.cookie.length;}
       return (unescape(document.cookie.substring(strbegin, strend)));
       }
     function setCookie(c_name,value,exp)
      {
       c_string=c_name+"="; 
       document.cookie=c_string + escape(value)+"; expires=" + exp.toGMTString();  
      }
     function removeCookie(c_name)
      {
      setCookie(c_name,"",new Date(0));
      }
     function checkUpdate() 
      {
             var exp=new Date();               
             var plusoneyear=exp.getTime()+(365 * 24 * 60 * 60 * 1000); 
             exp.setTime(plusoneyear);          
             var last=getCookie(cookiename);  
             var str=document.lastModified;    
             var update=new Date(str.substring(6,8),str.substring(0,2),str.substring(3,5),str.substring(9,11),str.substring(12,14),str.substring(15,17));
             
             if(last!=0)  
              {
              if(update.getTime()>last)   
               {                   
               window.alert("This page had been updated since you last visit!");}
              }
             else               
                { 
                window.alert("Welcome to "+document.title);  
                }             
             setCookie(cookiename,update.getTime(),exp); 
       }