URGENT. i want to display a sweet alert when a logout the user on other devices

If you want a 'sweet alert' like a pop-up, you'll need to implement something like websockets to receive a signal when the user is logged out.

The less 'sweet' but more easy approach is to create a page the user is redirected to when logged out because of another session. This redirect can be implemented in the code you're logging the user out.