add thumb column for post list

add thumb column

function add_thumbnail_column( $columns ) {
  $columns['thumbnail'] = __( 'Featured Images' );
	return $columns;
}

function display_thumbnail_column( $column_name, $post_id ) {
	if ( $column_name == 'thumbnail' ) {
		if ( has_post_thumbnail( $post_id ) ) {
			echo get_the_post_thumbnail( $post_id, array( 50, 50 ) );
		} else {
			_e( 'none' );
		}
	}
}

function register_thumbnail_column_hooks() {
	$post_type = isset( $_REQUEST['post_type'] ) ? $_REQUEST['post_type'] : 'post';
	if ( post_type_supports( $post_type, 'thumbnail' ) ) {
		add_filter( 'manage_' . $post_type . '_posts_columns', 'add_thumbnail_column' );
		add_action( 'manage_' . $post_type . '_posts_custom_column', 'display_thumbnail_column', 10, 2 );
	}
}
add_action( 'load-edit.php', 'register_thumbnail_column_hooks' );
if ( defined( 'DOING_AJAX' ) && DOING_AJAX ) {
    add_action( 'admin_init', 'register_thumbnail_column_hooks' );
}