What is the lifecycle of a Service Worker (install → activate → fetch)? How do you handle cache versioning and old worker cleanup?

Q: What is the lifecycle of a Service Worker (install → activate → fetch)? How do you handle cache versioning and old worker cleanup?

self.addEventListener('install', e => { e.waitUntil(caches.open('v2').then(c => c.addAll(['/','/style.css']))); }); self.addEventListener('activate', e => { e.waitUntil(caches.keys().then(keys => Promise.all(keys.map(k => k !== 'v2' && caches.delete(k))))); });

Difficulty: 5/10

service worker lifecycle, cache versioning, worker cleanup

Service Worker lifecycle: `install` (caching), `activate` (cleanup old caches), `fetch` (intercept requests). Use cache version names (e.g., `'v2'`) and delete old caches in `activate` event.

Service Worker lifecycle

Scenario Questions

0-2 years experience

1We have a static marketing site and you need to add offline support with a service worker. Walk me through the code you’d write for the install, activate, and fetch events, and how you’d version the cache.
2If you change the cache name in your service worker, what steps must you take to make sure the previous cache is removed and users don’t get stale assets?

2-5 years experience

Follow-up Questions

What is the lifecycle of a Service Worker (install → activate → fetch)? How do you handle cache versioning and old worker cleanup?

Difficulty: 5/10

service worker lifecycle, cache versioning, worker cleanup

Service Worker lifecycle: `install` (caching), `activate` (cleanup old caches), `fetch` (intercept requests). Use cache version names (e.g., `'v2'`) and delete old caches in `activate` event.

Service Worker lifecycle

Scenario Questions

0-2 years experience

2-5 years experience

What is the lifecycle of a Service Worker (install → activate → fetch)? How do you handle cache versioning and old worker cleanup?

Service Worker lifecycle: install (caching), activate (cleanup old caches), fetch (intercept requests). Use cache version names (e.g., 'v2') and delete old caches in activate event.

Scenario Questions

Follow-up Questions

What is the lifecycle of a Service Worker (install → activate → fetch)? How do you handle cache versioning and old worker cleanup?

Service Worker lifecycle: install (caching), activate (cleanup old caches), fetch (intercept requests). Use cache version names (e.g., 'v2') and delete old caches in activate event.

Scenario Questions

Follow-up Questions

Service Worker lifecycle: `install` (caching), `activate` (cleanup old caches), `fetch` (intercept requests). Use cache version names (e.g., `'v2'`) and delete old caches in `activate` event.

Service Worker lifecycle: `install` (caching), `activate` (cleanup old caches), `fetch` (intercept requests). Use cache version names (e.g., `'v2'`) and delete old caches in `activate` event.