$j = jQuery.noConflict();

$j(document).ready(
    function() {

        // Commentform Validation Plugin based on Code from Trevor Davis
        // http://trevordavis.net/blog/tutorial/use-jquery-to-enhance-your-wordpress-comment-form/
        $j( 'form#commentform' ).submit( function() {
            var hasError = false;
            $j( '.required' ).next().each( function() {
                if( $j.trim( $j(this).val() ) == '' ) {
                    $j(this).parent().fadeOut( 400 ).fadeIn( 400 );
                    hasError = true;
                }
            });
            if( hasError ) {
                return false;
            }
        });
    }
);