function set_cookie( cookie_name, cookie_value, cookie_expire_in_days ) {
  var expire_date = new Date();
  expire_date.setDate( expire_date.getDate() + cookie_expire_in_days );
  document.cookie= cookie_name + "=" + escape( cookie_value ) + ( ( cookie_expire_in_days == null ) ? "" : "; expires=" + expire_date.toGMTString() );
}

function get_cookie( cookie_name ) {
  if (document.cookie.length>0) {
    cookie_start = document.cookie.indexOf( cookie_name + "=" );
    if ( cookie_start != -1 ) { 
      cookie_start = cookie_start + cookie_name.length + 1; 
      cookie_end = document.cookie.indexOf( ";", cookie_start );
      if (cookie_end == -1 ) {
        cookie_end = document.cookie.length;
      }
      return unescape( document.cookie.substring( cookie_start, cookie_end ) );
    } 
  }
  return "";
}