Senior LevelHTML & Semantic Web
How do you architect an offline-first PWA caching strategy using the Cache Storage API?
❓ Interview Prompt: Explain Cache Storage API, Stale-While-Revalidate caching pattern, Cache First, and Network First offline fallbacks.
An Offline-First PWA architecture assumes network connectivity is unreliable, treating local cache as the primary data source.
Stale-While-Revalidate Pattern:
1
Service Worker responds immediately with cached asset from Cache Storage.
2
Concurrently fetches fresh copy from network in background.
3
Updates Cache Storage with fresh response for future requests.
Code Implementation Example
javascript
self.addEventListener('fetch', (event) => {
event.respondWith(
caches.open('dynamic-cache-v1').then((cache) => {
return cache.match(event.request).then((cachedResponse) => {
const fetchPromise = fetch(event.request).then((networkResponse) => {
cache.put(event.request, networkResponse.clone());
return networkResponse;
});
return cachedResponse || fetchPromise;
});
})
);
});💡Implementing Stale-While-Revalidate caching strategy in Service Worker.
🎯 Interview Key Takeaway
Use the Stale-While-Revalidate caching pattern in Service Workers to serve instant cached responses while updating cache in background.
#Offline-First#Cache Storage#Stale-While-Revalidate#Senior
Back to all HTML & Semantic Web Questions→