function getCookie(name)
    {
    // Returns string containing value of specified cookie or null if cookie does not exist
    var dc = document.cookie;
    var prefix = name + "=";
    var begin = dc.indexOf("; " + prefix);
    if (begin == -1)
      {
      begin = dc.indexOf(prefix);
      if (begin != 0) return null;
      }
    else begin += 2;
    var end = document.cookie.indexOf(";", begin);
    if (end == -1) end = dc.length;
    return unescape(dc.substring(begin + prefix.length, end));
    }