Is user online or not

https://www.wp-plugins-db.org/plugin/ajaxed-whos-online/

https://www.babatatas.com/?p=24

This plugin is really perfect but I don’t want to show the list of all online users. I just want to show whether the post author is online or not on single post page.

yeap, how could we check wheather user is online in some loop using user_id or not? quite a simple query i think..

if(is_user_logged_in()) :
  global $current_user;
  get_currentuserinfo();
  echo $current_user->display_name;
  /* green button stuff here */
else :
  /* offline stuff */
endif;