Shortcode

// Add Shortcode
function adele_slider_shortcode() {

	$result             = '';
	$include_javascript = plugin_dir_url( __FILE__ ) . 'assets/slick.min.js';
	$include_css        = plugin_dir_url( __FILE__ ) . 'assets/slick.min.css';
	$include_css_theme  = plugin_dir_url( __FILE__ ) . 'assets/slick-theme.css';
	
	$result             .= '<link rel="stylesheet" href="' . $include_css . '" />';
	$result             .= '<link rel="stylesheet" href="' . $include_css_theme . '" />';
	$result             .= '<script src="' . $include_javascript . '"></script>';
	$result             .= '<section class="regular slider">';
	
	// WP_Query arguments
	$args = array(
		'post_type'              => array( 'adele_front_slider' ),
		'post_status'            => array( 'publish' ),
		'nopaging'               => false,
		'posts_per_page'         => '50',
	);
	
	// The Query
	$adele_custom_query = new WP_Query( $args );
	
	// The Loop
	if ( $adele_custom_query->have_posts() ) {
		while ( $adele_custom_query->have_posts() ) {
			$adele_custom_query->the_post();
			$result        .= '<div>';
			$result        .= get_the_post_thumbnail( null, 'full' );
			$result        .= '</div>';
		}
	} else {
		// no posts found
	}
	
	// Restore original Post Data
	wp_reset_postdata();
	
	$result             .= '</section>';
	$result             .= "<script type='text/javascript'>jQuery(document).on('ready', function() {";
	$result             .= 'jQuery(".regular").slick({ dots: true, infinite: true, slidesToShow: 3, slidesToScroll: 3 });';
	$result             .= "});</script>";
	
	return $result;

}
add_shortcode( 'adele_slider_shortcode', 'adele_slider_shortcode' );