How to check if user is subscribed to browser push notifications?

Question

Notifications

There is a site that offers to allow the user to send notifications to the browser (push).
Is it possible to somehow check in js whether subscriptions are allowed for a user or not?
To, for example, if the user is not subscribed, display one message on the site, and if subscribed, then another.

Answer 1

if ('Notification' in window) {
  // API supported
} else {
  // API not supported
}