$callback = $params['callback'];
if ( $callback !== null ) {
$callback = preg_replace( "/[^][.\\'\\\"_A-Za-z0-9]/", '', $callback );
$callback = $params['callback'];
if ( $callback !== null ) {
$callback = preg_replace( "/[^][.\\'\\\"_A-Za-z0-9]/", '', $callback );