<article>
<?php
/**
 * Template name: AJAX Post Filter by Taxonomy
 *
 */

$args = array(
    'post_type' => 'post',
    'posts_per_page' => 10,
);

$query = new WP_Query( $args );

function tags_filter() {
    $tax = 'post_tag';
    $terms = get_terms( $tax );
    $count = count( $terms );

    if ( $count > 0 ): ?>
        <div class="post-tags">
        <?php
        foreach ( $terms as $term ) {
            $term_link = get_term_link( $term, $tax );
            echo '<a href="' . $term_link . '" class="tax-filter" title="' . $term->slug . '">' . $term->name . '</a> ';
        } ?>
        </div>
    <?php endif;
}

tags_filter();

if ( $query->have_posts() ): ?>
<div class="tagged-posts">
    <?php while ( $query->have_posts() ) : $query->the_post(); ?>

    <h2><a href="<?php the_permalink(); ?>"><?php the_title(); ?></a></h2>
    <?php the_excerpt(); ?>

    <?php endwhile; ?>
</div>

<?php else: ?>
    <div class="tagged-posts">
        <h2>No posts found</h2>
    </div>
<?php endif; ?>
</article>