The key to managing H5 application cache with Service Worker is to control the cache lifecycle and policies to improve performance and experience. 1. Cache version control: Name the cache (such as my-cache-v1) by adding a version number, upgrade the version during update and clear the old cache in the activate stage to avoid the old resources from polluting new content; 2. On-demand cache strategy: Static resources are cached for a long time with Cache First, API data is selected for Network First or expired Stale While Revalidate according to the frequency of change, dynamic pages are not cached or cached for a short time; 3. Clean useless cache: Delete the abandoned cache in the activate event to keep the storage neat; 4. Use Chrome DevTools to check the cache status and debug, and turn off automatic updates during development to ensure controllable behavior. Rational management can significantly improve performance and avoid caching confusion affecting the user experience.

Cache Storage is a critical part when using Service Worker to manage caches for H5 applications. It not only improves loading speed, but also enables offline access. But if not managed, the cache can become confusing and even affect the user experience.

1. Cache version control: Avoid old cache polluting new resources

Service Worker's caching mechanism does not automatically update resources like the browser defaults. You need to control the cache name yourself (such as adding a version number), otherwise the old cache will always exist, causing users to be unable to get the latest content.

For example:

 const CACHE_NAME = 'my-cache-v1';

Each time you update the cache policy or resource list, you should upgrade the cache version (such as v2 instead) and clean the old cache when installing the new Service Worker:

• Skip wait in install phase ( self.skipWaiting() )
• Delete old cache in activate stage

This ensures that users do not see expired content because of the residual old cache.

2. On-demand caching strategy: Don’t cache them all in one go

Many people like to cache all requests at the beginning, but the result is a problem. For example, if some frequently changing interface data are cached for too long, the user will see error messages.

It is recommended to adopt a hierarchical caching strategy:

• Static resources (such as JS, CSS, and pictures): suitable for long-term caching, you can use the Cache First strategy
• API interface data : Depending on the situation, some are suitable for Network First or Stale While Revalidate with expiration time
• Dynamic page : Caching is usually not recommended, or shorter cache time is set

You can make judgments based on the URL path in fetch event and select different cache policies.

3. Cleaning up useless caches: regular maintenance is important

Even if you do version control, multiple abandoned caches may accumulate due to testing, online and other reasons. Although these caches will not directly affect the function, they will occupy the user's storage space.

It is recommended to clean caches that are no longer used in activate event:

 self.addEventListener('activate', (event) => {
  const validCaches = ['my-cache-v2'];
  event.waitUntil(
    caches.keys().then((keys) =>
      keys.filter((key) => !validCaches.includes(key)).map((key) => caches.delete(key))
    )
  );
});

This keeps the cache clean and reduces redundant data.

4. Use debugging tools to check cache status

Chrome DevTools provides the Cache Storage viewing function under the Application tab, and you can directly see which resources are currently cached and which cache name is corresponding to it. This is very helpful for troubleshooting cache failures, resource not updated, etc.

In addition, it is recommended to turn off the "Update on reload" option during the development phase and manually trigger the Service Worker update to ensure that the cache behavior is in line with expectations.

Basically that's it. Rational use of Cache Storage can significantly improve application performance and user experience, but pay attention to controlling the cache life cycle and strategy to avoid adverse effects.

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