[WordPress] Display Popular Posts by Page Views

popular-posts-functions.php

<?php

/** 
 * Sets the post view count
 * @params ($postID) Current post ID
 */
function namespace_set_post_views($postID) {
    
    $count_key = 'namespace_post_views_count';
    $count     = get_post_meta($postID, $count_key, true);

    if ( $count === ''){
        $count = 0;
        delete_post_meta($postID, $count_key);
        add_post_meta($postID, $count_key, '0');
    } else {
        $count++;
        update_post_meta($postID, $count_key, $count);
    }

}

/** 
 * Track post views on page load
 * @params ($postID) Current post ID
 */
function namespace_track_post_views ($post_id) {

    if ( !is_single() ) return;
    
    if ( empty ( $post_id) ) {
        global $post;
        $post_id = $post->ID;    
    }
    
    namespace_set_post_views($post_id);

}

/**
 * To keep the count accurate, remove prefetching of posts
 */
remove_action( 'wp_head', 'adjacent_posts_rel_link_wp_head', 10, 0);

/**
 * Add post view tracker to page head
 */
add_action( 'wp_head', 'namespace_track_post_views');

?>

popular-posts-loop.php

<?php

/** 
 * Popular Posts WP Query
 */
  $args = array( 
    'posts_per_page' => 4,
    'meta_key'       => 'namespace_post_views_count',
    'orderby'        => 'meta_value_num',
    'order'          => 'DESC'
  );

  $popularpost = new WP_Query( $args );
?>

<?php if ( $popularpost->have_posts() ) : ?>
<ul>

  <?php while ( $popularpost->have_posts() ) : $popularpost->the_post(); ?>

  <li>
    <a href="<?php the_permalink(); ?>" title="<?php the_title(); ?>"><?php the_title(); ?></a>
  </li>

  <?php endwhile; wp_reset_postdata(); ?>

</ul>
<?php endif; ?>