Service Worker Vocabulary
Master Service Worker vocabulary: registration, install/activate lifecycle, fetch interception, cache strategies (cache-first, network-first), and background sync.
Vocabulary Reference
- registration
- The initial step: navigator.serviceWorker.register('/sw.js') tells the browser to download, parse, and begin installing the service worker script.
- install event
- Fired once when a new service worker version is first installed. Typically used with event.waitUntil() to pre-cache static assets before the worker takes control.
- activate event
- Fired after a new service worker takes control (old clients are gone). Used to clean up outdated caches from previous versions.
- fetch interception
- Service workers listen for the fetch event on every network request made by controlled pages. The handler can respond with a cached response, a modified request, or let the request pass through.
- cache-first
- Serve from the cache immediately; fall back to the network only on a cache miss. Best for versioned static assets that rarely change.
- network-first
- Always try the network first; serve from cache only if the network request fails. Suitable for frequently updated API responses where freshness matters.
- background sync
- An API that defers actions queued while offline (e.g. form submissions) and re-runs them via the service worker's sync event once connectivity is restored.