Intermediate LevelHTML & Semantic Web
How do Service Workers intercept network requests in Progressive Web Apps (PWAs)?
❓ Interview Prompt: Explain Service Worker lifecycle (register, install, activate), fetch event interception, and offline caching.
A Service Worker is an event-driven background Web Worker that acts as a client-side programmable network proxy between the browser and network.
Capabilities:
•
Fetch Interception: Listens to 'fetch' events, serving cached offline assets instantly from the Cache Storage API.
•
Background Sync: Syncs offline form submissions when network connectivity recovers.
Code Implementation Example
javascript
// sw.js - Service Worker fetch event network interception
self.addEventListener('fetch', (event) => {
event.respondWith(
caches.match(event.request).then((cachedResponse) => {
return cachedResponse || fetch(event.request);
})
);
});💡Intercepting network fetch requests inside Service Worker script.
🎯 Interview Key Takeaway
Service Workers act as programmable network proxies, intercepting fetch requests to serve offline cached assets.
#Service Worker#PWA#Fetch Interception#Offline#Intermediate
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