Highlight comments of all the site authors

Question

On our WordPress page, we're several people who write articles. All these people are in different user roles. Some are editors, others are only authors and I'm the admin.

I know that you can highlight a comment or a reply of the posts author by writing

.commentlist .bypostauthor {
    # some styles
}

in your CSS file, but how could I alter this, so that every comment or reply written by a registered user of any of the following user roles author, editor and admin is highlighted?

Thanks for helping me out :)

Answer 1

There's a filter called comment_class for that :

apply_filters( 'comment_class', $classes, $class, $comment->comment_ID, $comment, $post_id );

Source

Just use the argument comment which is an object and you'll get $comment->user_id which could be useful to get user role and add your classes.

EDIT:

add_filter( 'comment_class', 'wpse_253517_comment_class', 10, 5 );
function wpse_253517_comment_class( $classes, $class, $comment_ID, $comment, $post_id  ) {

    if ( 0 === (int) $comment->user_id  ) {
        return $classes;
    }

     $user_data = get_userdata( $comment->user_id );
     $role      = reset( $user_data->roles );

    switch( $role ) {
        case 'subscriber':
            $classes[] = 'is-subscriber';
        break;

        // here would be other cases, other roles     

        default:
        return $classes;
    }

    return $classes;

}