function getCookie(NameOfCookie) { 
  if (document.cookie.length > 0) { 
    begin = document.cookie.indexOf(NameOfCookie+"=");
    if (begin != -1) { 
      begin += NameOfCookie.length+1;
      end = document.cookie.indexOf(";", begin);
      if (end == -1) {
        end = document.cookie.length;
      };
      return unescape(document.cookie.substring(begin, end)); 
    };
  };
  return null;
}

function setCookie(NameOfCookie, value, expiredays) { 
  var ExpireDate = new Date ();
  ExpireDate.setTime(ExpireDate.getTime() + (expiredays * 24 * 3600 * 1000));
  document.cookie = NameOfCookie + "=" + escape(value) + 
    ((expiredays == null) ? "" : "; expires=" + ExpireDate.toGMTString());
}

function delCookie(NameOfCookie) {
  if (getCookie(NameOfCookie)) {
    document.cookie = NameOfCookie + "=" + "; expires=Thu, 01-Jan-70 00:00:01 GMT";
  }
}