function setCookie(cookieName,cookieValue,nDays){
// sets a cookie of cookieName with value cookieValue which will expire in nDays
 var today = new Date();
 var expire = new Date();
 if (nDays==null || nDays==0) nDays=90;
 
 var numSeconds = 1000 * 86400 * nDays;
 
 expire.setTime(today.getTime() + numSeconds);
 document.cookie = cookieName+"="+escape(cookieValue)
                 + ";expires="+expire.toGMTString();
}

function clearCookie(cookieName){
// clears a cookie
  var today = new Date();
  var expire = new Date();
  expire.setTime(today.getTime() - 3600);
  document.cookie = cookieName+"="+escape('')+";expires="+expire.toGMTString();
}