php GZIP javascript

ob_start('ob_gzhandler');
header("Cache-Control: public");
header("Pragma: cache");
$offset = 60*60*24*60;
$ExpStr = "Expires: ".gmdate("D, d M Y H:i:s",time() + $offset)." GMT";
$LmStr = "Last-Modified: ".gmdate("D, d M Y H:i:s",filemtime(__FILE__))." GMT";
header($ExpStr);
header($LmStr);
header('Content-Type: text/javascript; charset: UTF-8');
?>