PushSubscriptiontilauksen

PushSubscription is a representation of a user's subscription to push notifications in the Web Push API. It is created by calling subscribe on a PushManager exposed by a service worker, typically after the user has granted permission for notifications. A PushSubscription describes how the push service should deliver messages to the user's device or browser.

A subscription includes an endpoint URL that the application server uses to send push messages, an optional expirationTime, and a set of cryptographic keys used to secure the message payload. The keys object usually contains two properties: p256dh (the user's public key for encryption) and auth (an authentication secret).

To deliver a notification, the server sends a message to the subscription's endpoint using the Web Push protocol. The payload is encrypted with the keys and delivered by the push service. The server typically authenticates itself to the push service using Voluntary Application Server Identification (VAPID).

Clients can manage subscriptions by calling unsubscribe() on the PushSubscription object, and the server should remove the corresponding record when unsubscribed or when the endpoint becomes invalid. If expirationTime is provided, the client may re-subscribed as needed.

Usage considerations: Push subscriptions are browser- and device-specific; users can revoke permission; endpoints may change; regard privacy and data minimization; support is broad but varies across browsers and platforms; developers should handle failures and fallback notification methods.