Send Push Desktop notification to Browser even site's tab is closed

i want to send desktop notification to browser when tab of site is closed i successfully send desktop notification when site is open with laravel and pusher but could not send when site tab is closed i try [https://developers.google.com/web/updates/2015/03/push-notifications-on-the-open-web] but i could not find the solution to send desktop push notification of closed site.

via Chebli Mohamed