public function sendJSON($data) {
        if(!headers_sent()) header('Content-Type: application/json; charset=utf-8', true, 200);
        echo json_encode($data, JSON_HEX_TAG | JSON_HEX_APOS | JSON_HEX_QUOT | JSON_HEX_AMP | JSON_UNESCAPED_UNICODE);
        exit;
    }