I should write this down

I did write this down, but I buried it in another blog post.

Sometimes you don’t want to display the featured image but you don’t want to remove the option from your theme.

This snippet in a plugin or child theme’s functions.php file will accomplish that.

add_filter( 'post_thumbnail_html', 'mh_post_image_html', 10, 3 );

function mh_post_image_html( $html, $post_id, $post_image_id ) {
if( is_single() ) {
     $html = '<!-- The featured image would be here if I chose to display it. ;) -->';
     }
return $html;
}

It doesn’t disable support for post thumbnails but replaces the code with an HTML comment if the post is_single() using the post_thumbnail_html filter. You can use other conditionals as well and even edit the HTML before returning it.