Automatically add facet label as a heading before any facets with available options to filter by.

functions.php

<?php

/**
 * Adds facet label as a heading before any facets with available options.
 * 
 * @author  Mike Hemberger @JiveDig.
 *
 * @param   string  $output  The facet HTML.
 * @param   array   $params  The shortcode/function parameters.
 *
 * @return  string  The modified output.
 */
add_filter( 'facetwp_facet_html', function( $output, $params ) {
	// Bail if no facet options.
	if ( empty( $params['values'] ) ) {
		return $output;
	}
	// Return label as heading.
	return sprintf( '<h3>%s</h3>%s', $params['facet']['label'], $output );
}, 10, 2 );