Use Service Worker to implement H5 offline caching

Service Worker implements H5 offline caching, which is a backend-run service responsible for managing caches and intercepting network requests. The principle steps include: installation (initialization cache), activation (control network request), network request interception (providing cache files), and update (update cache). The advantages are improved offline availability, performance optimization, traffic savings and security. Use steps: Create a Service Worker script file, register with the application, define event handlers in the script file, initialize the cache, activate the cache, and check whether the request can be satisfied from the cache.

H5 Service Worker implementation for offline cache

Service Worker is a front-end technology for offline caching of H5 applications. It is a lightweight service that runs in the background in the browser and is responsible for managing caches, intercepting network requests and responding to offline events.

Implementation principle:

Service Worker implements offline caching through the following steps:

1. Installation phase: The script file of Service Worker is loaded and executed. Here, the cache can be initialized and the necessary files can be saved.
2. Activation phase: Service Worker is active, which can control network requests and intercept requests to cached files.
3. Network request interception: Service Worker listens to all network requests. If the requested file exists in the cache, it will intercept the request and provide the cached file.
4. Update phase: When a new Service Worker script is available, the browser triggers an update event. The new Service Worker will be installed and activated, and you can update the cache or perform other update operations.

Advantages:

• Offline Availability: Allows users to access applications without a network connection.
• Performance optimization: Improve application loading speed by caching frequently requested files.
• Save traffic: Reduce data traffic consumption by using cached files offline.
• Improve security: Prevent applications from CSRF or other attacks when they are disconnected from the network.

Steps to use:

1. Create a Service Worker script file (for example, sw.js).
2. Register Service Worker with the application's index.html file.
3. In the Service Worker script file, define install, activate, and fetch event handlers.
4. In the install handler, initialize the cache and add the necessary resource files.
5. In the activate handler, activate the cache and clean up the old version.
6. In the fetch handler, check whether the request can be satisfied from the cache, and if so, return the cached file.

For example:

 <code class="javascript">// sw.js self.addEventListener('install', (event) => { event.waitUntil( caches.open('my-cache').then((cache) => { cache.addALL([ '/', '/index.html', '/styles.css', '/scripts.js' ]); }) ); }); self.addEventListener('activate', (event) => { event.waitUntil( caches.keys().then((cacheNames) => { Promise.all( cacheNames.map((cacheName) => { if (cacheName !== 'my-cache') { return caches.delete(cacheName); } }) ); }) ); }); self.addEventListener('fetch', (event) => { event.respondWith( caches.match(event.request).then((response) => { return response || fetch(event.request); }) ); });</code>

 <code class="html"><!-- index.html --> <script> if (&#39;serviceWorker&#39; in navigator) { navigator.serviceWorker.register(&#39;sw.js&#39;); } </script></code>

The above is the detailed content of Use Service Worker to implement H5 offline caching. For more information, please follow other related articles on the PHP Chinese website!