Explain the difference between cache, network, and stale-while-revalidate caching strategies in SW.

Question

ICSM Computer · Answer

1. Cache-First Strategy
“Serve from the cache if you can, fall back to the network if you must.”
How it works:
Service Worker looks in the cache.If found → return cached version immediately.If not found → fetch from the network, store in cache for next time.
Best for:
Assets that rarely change (images, fonts, libraries like Bootstrap or jQuery).Offline-friendly resources.
Pros:
Fast (no network request if cached).Works offline.
Cons:
May serve outdated content unless you have a manual update flow.
Example:
event.respondWith(
  caches.match(event.request).then(cachedResponse =andgt; {
    return cachedResponse || fetch(event.request);
  })
);
2. Network-First Strategy
“Always try the network first, fall back to the cache if offline.”
How it works:
Try fetching from the network.If successful → return response and update cache.If network fails (offline or timeout) → use cached version.
Best for:
Dynamic content (news feeds, social media, APIs).Data that changes frequently.
Pros:
Always fresh when online.Still works offline with cached backup.
Cons:
Slower if network latency is high.No content if both cache and network fail.
Example:
event.respondWith(
  fetch(event.request)
    .then(response =andgt; {
      const clone = response.clone();
      caches.open('dynamic').then(cache =andgt; cache.put(event.request, clone));
      return response;
    })
    .catch(() =andgt; caches.match(event.request))
);
3. Stale-While-Revalidate Strategy
“Serve from cache immediately, but quietly update it in the background.”
How it works:
Check cache:
If found → return it instantly to the user.Meanwhile, fetch from network in background.When network returns → update cache so next request is fresh.
Best for:
Content that changes occasionally but must load instantly (blogs, avatars, CSS files with infrequent changes).
Pros:
Instant load from cache.Updates happen automatically in the background.
Cons:
First view after a change might show old content.Requires logic to notify user of updates if needed.
Example:
event.respondWith(
  caches.match(event.request).then(cachedResponse =andgt; {
    const fetchPromise = fetch(event.request).then(networkResponse =andgt; {
      caches.open('dynamic').then(cache =andgt; cache.put(event.request, networkResponse.clone()));
      return networkResponse;
    });
    return cachedResponse || fetchPromise;
  })
);
Quick Comparison Table
Strategy
Priority
Offline Ready
Freshness
Use Case
Cache-First
Cache → Network
Yes
Might be old
Static assets, fonts, images
Network-First
Network → Cache
Yes
Fresh
APIs, frequently changing data
Stale-While-Revalidate
Cache + Background Update
Yes
Slightly stale
Semi-static content, fast UX
and

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Explain the difference between cache, network, and stale-while-revalidate caching strategies in SW.

ICSM Computer

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1 Answers

1. Cache-First Strategy

2. Network-First Strategy

3. Stale-While-Revalidate Strategy

Quick Comparison Table

Liked By

Strategy	Priority	Offline Ready	Freshness	Use Case
Cache-First	Cache → Network	Yes	Might be old	Static assets, fonts, images
Network-First	Network → Cache	Yes	Fresh	APIs, frequently changing data
Stale-While-Revalidate	Cache + Background Update	Yes	Slightly stale	Semi-static content, fast UX