/******************************************************************
 * setCookie()                                                    *
 * --> set a javascript cookie                                    *
 * @param cookieName [string]: name of the cookie                 *
 * @param value [string]: content of cookie                       *
 * @param expiredays [int]: number of days before expiration      *
 ******************************************************************/
function setCookie(cookieName, value, expiredays)
{
   var ExpireDate = new Date();
   ExpireDate.setTime(ExpireDate.getTime() + (expiredays*24*3600*1000));

   document.cookie = cookieName + "=" + escape(value) + ((expiredays == -1) ? "" : "; expires=" +
         ExpireDate.toGMTString()) + ";path=/";
}

/******************************************************
 * deleteCookie()                                     *
 * --> delete a cookie                                *
 * @param name [string]: name of cookie to delete     *
 ******************************************************/
function deleteCookie(name)
{
   setCookie(name,"",-1);
}

/******************************************************************
 * getCookie()                                                    *
 * --> retrieve cookie information                                *
 * @param cookieName [string]: name of cookie to retrieve         *
 * @return [string]: if cookie exists, its value is returned      *
 *                   otherwise null is returned                   *
 ******************************************************************/
function getCookie(cookieName)
{
   if(document.cookie.length > 0)
   {
      begin = document.cookie.indexOf(cookieName+"=");

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