Add featured image column to WP admin panel - posts AND pages

functions.php

<?php

/**
 * Add featured image column to WP admin panel - posts AND pages
 * See: https://bloggerpilot.com/featured-image-admin/
 */

// Set thumbnail size
add_image_size( 'j0e_admin-featured-image', 60, 60, false );

// Add the posts and pages columns filter. Same function for both.
add_filter('manage_posts_columns', 'j0e_add_thumbnail_column', 2);
add_filter('manage_pages_columns', 'j0e_add_thumbnail_column', 2);
function j0e_add_thumbnail_column($j0e_columns){
  $j0e_columns['j0e_thumb'] = __('Image');
  return $j0e_columns;
}
 
// Add featured image thumbnail to the WP Admin table.
add_action('manage_posts_custom_column', 'j0e_show_thumbnail_column', 5, 2);
add_action('manage_pages_custom_column', 'j0e_show_thumbnail_column', 5, 2);
function j0e_show_thumbnail_column($j0e_columns, $j0e_id){
  switch($j0e_columns){
    case 'j0e_thumb':
    if( function_exists('the_post_thumbnail') )
      echo the_post_thumbnail( 'j0e_admin-featured-image' );
    break;
  }
}

// Move the new column at the first place.
add_filter('manage_posts_columns', 'j0e_column_order');
function j0e_column_order($columns) {
  $n_columns = array();
  $move = 'j0e_thumb'; // which column to move
  $before = 'title'; // move before this column

  foreach($columns as $key => $value) {
    if ($key==$before){
      $n_columns[$move] = $move;
    }
    $n_columns[$key] = $value;
  }
  return $n_columns;
}

// Format the column width with CSS
add_action('admin_head', 'j0e_add_admin_styles');
function j0e_add_admin_styles() {
  echo '<style>.column-j0e_thumb {width: 60px;}</style>';
}

?>