The onactivate property of the ServiceWorkerGlobalScope interface is an event handler fired whenever an activate event occurs (when the service worker activates). This happens after installation, when the page to be controlled by the service worker refreshes.
The ServiceWorkerGlobalScope.onpushsubscriptionchange event of the ServiceWorkerGlobalScope interface is fired whenever a push subscription has been invalidated (or is about to become so). This offers an opportunity to resubscribe in order to continue receiving push messages, if desired. This might happen if, for example, the push service sets an expiration time a subscription.