function getCookieValue (offset) {
  
  var endstr = document.cookie.indexOf (";", offset);
  if (endstr == -1)
    endstr = document.cookie.length;
    
  return unescape(document.cookie.substring(offset, endstr));
}


/**
 * Function to return the value of the cookie specified by "name".
 * @param name String object containing the cookie name.
 * @return String object containing the cookie value, or null if the cookie does not exist.
 */
function getCookie (name) {
  var arg = name + "=";
  var alen = arg.length;
  var clen = document.cookie.length;
  var i = 0;

  while (i < clen) {
    var j = i + alen;
    
    if (document.cookie.substring(i, j) == arg) {
      return getCookieValue (j);
    }
    
    i = document.cookie.indexOf(" ", i) + 1;
    
    if (i == 0) 
      break; 
  }
  
  return null;
}

  
/**
 * Function to create or update a cookie.
 * @param name String object object containing the cookie name.
 * @param value String object containing the cookie value.  May contain any valid string characters.
 * @param [expires] Date object containing the expiration data of the cookie.  If
 *                    omitted or null, expires the cookie at the end of the current session.
 * @param [path] String object indicating the path for which the cookie is valid.
 *               If omitted or null, uses the path of the calling document.
 * @param [domain] String object indicating the domain for which the cookie is
 *                 valid.  If omitted or null, uses the domain of the calling document.
 * @param [secure] Boolean (true/false) value indicating whether cookie transmission
 *                 requires a secure channel (HTTPS).  
 *
 * The first two parameters are required.  The others, if supplied, must
 * be passed in the order listed above.  To omit an unused optional field,
 * use null as a place holder.  For example, to call SetCookie using name,
 * value and path, you would code:
 *
 * setCookie ("myCookieName", "myCookieValue", null, "/");
 *
 * Note that trailing omitted parameters do not require a placeholder.
 *
 * To set a secure cookie for path "/myPath", that expires after the
 *  current session, you might code:
 *
 * setCookie (myCookieVar, cookieValueVar, null, "/myPath", null, true);
 *
 */
function setCookie (name, value) {
  var argv = setCookie.arguments;
  var argc = setCookie.arguments.length;
  var expires = (argc > 2) ? argv[2] : null;
  var path = (argc > 3) ? argv[3] : null;
  var domain = (argc > 4) ? argv[4] : null;
  var secure = (argc > 5) ? argv[5] : false;
  
  document.cookie = name + "=" + escape (value) +
    ((expires == null) ? "" : ("; expires=" + expires.toGMTString())) +
    ((path == null) ? "" : ("; path=" + path)) +
    ((domain == null) ? "" : ("; domain=" + domain)) +
    ((secure == true) ? "; secure" : "");
}


/**
 * Function to delete a cookie. (Sets expiration date to current date/time)
 * @param name String object containing the cookie name
 */
function deleteCookie (name) {
  var exp = new Date();
  exp.setTime (exp.getTime() - 1);  // This cookie is history
  
  var cval = GetCookie (name);
  document.cookie = name + "=" + cval + "; expires=" + exp.toGMTString();
}