function setCookie(name,value)
{
     var Days = 30;
     var exp   = new Date();     //new Date("December 31, 9998");
         exp.setTime(exp.getTime() + Days*24*60*60*1000);
         document.cookie = name + "="+ escape (value) + ";expires=" + exp.toGMTString();
}
function getCookie(name)
{
     var arr,reg=new RegExp("(^| )"+name+"=([^;]*)(;|$)");
         if(arr=document.cookie.match(reg)) return unescape(arr[2]);
         else return null;
}
function delCookie(name)
{
     var exp = new Date();
         exp.setTime(exp.getTime() - 1);
     var cval=getCookie(name);
         if(cval!=null) document.cookie= name + "="+cval+";expires="+exp.toGMTString();
}