if ($bp->current_component == $bp->groups->slug && $bp->is_single_item){}
Is how I detect if the user is in a group page in the member theme. Such as: /groups/cats
if ( $bp->current_component == $bp->groups->slug && empty( $bp->current_action ) ) {}
Is how I detect is the user is in a group directory. The group directory doesn’t have anything after /groups. There’s no ‘action’ to detect.
If you take a look at bp-groups.php groups_setup_nav() you’ll see all the stuff bp sets when a user vists one of their groups.
