Stale-While-Revalidate Strategy

1. Introduction

The Stale-While-Revalidate strategy is a caching strategy that allows web applications to serve stale content while asynchronously updating the cache in the background. This is particularly useful in Progressive Web Apps (PWAs) where smooth user experience is paramount, as it reduces loading times and enhances performance.

2. Key Concepts

3. Implementation

To implement the Stale-While-Revalidate strategy in a PWA, you can use the Service Worker API. Below is a basic example:

self.addEventListener('fetch', function(event) {
    event.respondWith(
        caches.open('my-cache').then(function(cache) {
            return cache.match(event.request).then(function(response) {
                // Stale response
                const fetchPromise = fetch(event.request).then(function(networkResponse) {
                    cache.put(event.request, networkResponse.clone());
                    return networkResponse;
                });
                return response || fetchPromise; // Return cached response or fetch
            });
        })
    );
});
                

This code listens for fetch events, checks if there's a cached response, and fetches the latest data in the background while serving stale content immediately.

4. Best Practices

• Always set appropriate cache expiration times to avoid serving stale data for too long.
• Prioritize critical resources to ensure fast loading times.
• Consider user experience: if the content is not critical, serving stale content is acceptable.
• Monitor and optimize cache sizes to prevent overflow.

5. FAQ