title: Send A Notification when PWA is Closed
body: <p>I have made a PWA Todo List App (<a href="https://adrish-m.github.io" rel="nofollow noreferrer">Link To App</a>) using Angular.
  I am now planning on adding Notifications which can reach the user when the app is closed.
  Since it is a PWA which works offline, I cannot depend on Push Notifications.
  Thanks in advance</p>