Filter WordPress posts by multiple custom taxonomy terms with AJAX Raw

filter-posts-mt.php

<?php
/**
 * AJAC filter posts by taxonomy term
 */
function vb_filter_posts_mt() {

	if( !isset( $_POST['nonce'] ) || !wp_verify_nonce( $_POST['nonce'], 'bobz' ) )
		die('Permission denied');

	/**
	 * Default response
	 */
	$response = [
		'status'  => 500,
		'message' => 'Something is wrong, please try again later ...',
		'content' => false,
		'found'   => 0
	];


	$all     = false;
	$terms   = $_POST['params']['terms'];
	$page    = intval($_POST['params']['page']);
	$qty     = intval($_POST['params']['qty']);
	$pager   = isset($_POST['pager']) ? $_POST['pager'] : 'pager';
	$tax_qry = [];
	$msg     = '';

	/**
	 * Check if term exists
	 */
	if (!is_array($terms)) :
		$response = [
			'status'  => 501,
			'message' => 'Term doesn\'t exist',
			'content' => 0
		];

		die(json_encode($response));
	else :

		foreach ($terms as $tax => $slugs) :

			if (in_array('all-terms', $slugs)) {
				$all = true;
			}

			$tax_qry[] = [
				'taxonomy' => $tax,
				'field'    => 'slug',
				'terms'    => $slugs,
			];
		endforeach;
	endif;

	/**
	 * Setup query
	 */
	$args = [
		'paged'          => $page,
		'post_type'      => 'post',
		'post_status'    => 'publish',
		'posts_per_page' => $qty,
	];

	if ($tax_qry && !$all) :
		$args['tax_query'] = $tax_qry;
	endif;

	$qry = new WP_Query($args);

	ob_start();
		if ($qry->have_posts()) :
			while ($qry->have_posts()) : $qry->the_post(); ?>

				<article class="loop-item">
					<header>
						<h2 class="entry-title"><a href="<?php the_permalink(); ?>"><?php the_title(); ?></a></h2>
					</header>
					<div class="entry-summary">
						<?php the_excerpt(); ?>
					</div>
				</article>

			<?php endwhile;

			/**
			 * Pagination
			 */
			if ( $pager == 'pager' )
				vb_mt_ajax_pager($qry,$page);


			foreach ($tax_qry as $tax) :
				$msg .= 'Displaying terms: ';

				foreach ($tax['terms'] as $trm) :
					$msg .= $trm . ', ';
				endforeach;

				$msg .= ' from taxonomy: ' . $tax['taxonomy'];
				$msg .= '. Found: ' . $qry->found_posts . ' posts';
			endforeach;

			$response = [
				'status'  => 200,
				'found'   => $qry->found_posts,
				'message' => $msg,
				'method'  => $pager,
				'next'    => $page + 1
			];

			
		else :

			$response = [
				'status'  => 201,
				'message' => 'No posts found',
				'next'    => 0
			];

		endif;

	$response['content'] = ob_get_clean();

	die(json_encode($response));

}
add_action('wp_ajax_do_filter_posts_mt', 'vb_filter_posts_mt');
add_action('wp_ajax_nopriv_do_filter_posts_mt', 'vb_filter_posts_mt');


/**
 * Shortocde for displaying terms filter and results on page
 */
function vb_filter_posts_mt_sc($atts) {

	$a = shortcode_atts( array(
		'tax'      => 'post_tag', // Taxonomy
		'terms'    => false, // Get specific taxonomy terms only
		'active'   => false, // Set active term by ID
		'per_page' => 12, // How many posts per page,
		'pager'    => 'pager' // 'pager' to use numbered pagination || 'infscr' to use infinite scroll
	), $atts );

	$result = NULL;
	$terms  = get_terms($a['tax']);

	if (count($terms)) :
		ob_start(); ?>
			<div id="container-async" data-paged="<?= $a['per_page']; ?>" class="sc-ajax-filter sc-ajax-filter-multi">
				<ul class="nav-filter">
					<li>
						<a href="#" data-filter="<?= $terms[0]->taxonomy; ?>" data-term="all-terms" data-page="1">
							Show All
						</a>
					</li>
					<?php foreach ($terms as $term) : ?>
						<li<?php if ($term->term_id == $a['active']) :?> class="active"<?php endif; ?>>
							<a href="<?= get_term_link( $term, $term->taxonomy ); ?>" data-filter="<?= $term->taxonomy; ?>" data-term="<?= $term->slug; ?>" data-page="1">
								<?= $term->name; ?>
							</a>
						</li>
					<?php endforeach; ?>
				</ul>

				<div class="status"></div>
				<div class="content"></div>

				<?php if ( $a['pager'] == 'infscr' ) : ?>
					<nav class="pagination infscr-pager">
						<a href="#page-2" class="btn btn-primary">Load More</a>
					</nav>
				<?php endif; ?>
			</div>
		
		<?php $result = ob_get_clean();
	endif;

	return $result;
}
add_shortcode( 'ajax_filter_posts_mt', 'vb_filter_posts_mt_sc');


/**
 * Pagination
 */
function vb_mt_ajax_pager( $query = null, $paged = 1 ) {

	if (!$query)
		return;

	$paginate = paginate_links([
		'base'      => '%_%',
		'type'      => 'array',
		'total'     => $query->max_num_pages,
		'format'    => '#page=%#%',
		'current'   => max( 1, $paged ),
		'prev_text' => 'Prev',
		'next_text' => 'Next'
	]);

	if ($query->max_num_pages > 1) : ?>
		<ul class="pagination">
			<?php foreach ( $paginate as $page ) :?>
				<li><?php echo $page; ?></li>
			<?php endforeach; ?>
		</ul>
	<?php endif;
}

Thank you for your message. I will try to fix it using console log.

I have used this below code for that,

msg = textStatus;
if (textStatus === 'success') {
    msg = data.responseJSON.found;
}
$status.text('Posts found: ' + msg);

I have also fixed it the issue of "Posts found: undefined" (when I click on load more button again again and when I reach button like this "You reached the end"). Thank you so much for amazing coding.

@tanmaypatel86 glad to hear that, good work!

Thank you :)