Badging API - Web APIs | MDN
The Badging API gives web developers a method of setting a badge on a document or application, to act as a notification that state has changed without displaying a more distracting notification. A common use case for this would be an application with a messaging feature displaying a badge on the app icon to show that new messages have arrived.
https://developer.mozilla.org/en-US/docs/Web/API/Badging_API
