Using the JavaScript Cache API for dynamic content caching

23 Oct 2023

As web developers, we are constantly looking for ways to improve the performance and user experience of our websites and web applications. One important aspect of this is caching - the process of storing commonly accessed resources locally so that they can be retrieved more quickly.

In this blog post, we will explore how to use the JavaScript Cache API to implement dynamic content caching in our web applications. The Cache API is part of the Service Worker API and provides a flexible way to store and retrieve requests and responses. Let’s get started!

What is Dynamic Content Caching?
Using the Cache API
Caching Dynamic Content
Retrieving Cached Content
Updating Cached Content
Conclusion

What is Dynamic Content Caching?

Dynamic content caching refers to the process of caching resources that are dynamically generated based on user interactions or server-side processes. This can include API responses, database queries, or personalized content.

By caching dynamic content, we can reduce the load on the server and improve the responsiveness of our applications. The Cache API allows us to store the responses of these dynamic requests and serve them from the cache instead of making repeated network requests.

Using the Cache API

To use the Cache API, we first need to check if the browser supports it. We can do this by using the caches global object:

if ('caches' in window) {
  // Cache API is supported
} else {
  // Cache API is not supported
}

Once we have confirmed the support, we can open a cache and start using it:

caches.open('my-cache').then(cache => {
  // Cache is now open and ready to use
});

The caches.open method returns a promise that resolves to a cache object. We can then use this cache object to store and retrieve requests and responses.

Caching Dynamic Content

To cache dynamic content, we need to intercept the network requests and store the responses in the cache. We can achieve this by using a service worker, which is a script that runs in the background and can intercept network requests.

Here’s an example of how we can cache a dynamic API response using the Cache API and a service worker:

self.addEventListener('fetch', event => {
  event.respondWith(
    caches.open('my-cache').then(cache => {
      return cache.match(event.request).then(response => {
        if (response) {
          // Return the cached response
          return response;
        }

        // If not cached, fetch the response from the network
        return fetch(event.request).then(networkResponse => {
          // Cache the response for future use
          cache.put(event.request, networkResponse.clone());

          // Return the network response
          return networkResponse;
        });
      });
    })
  );
});

In this example, we listen for the fetch event in the service worker and check if the requested resource is already cached. If it is, we return the cached response. Otherwise, we fetch the response from the network, store it in the cache, and return the network response.

Retrieving Cached Content

To retrieve cached content, we can use the cache.match method. This method takes a request and returns a promise that resolves to the corresponding response if it exists in the cache. Here’s an example:

caches.open('my-cache').then(cache => {
  cache.match(request).then(response => {
    if (response) {
      // Cached response found
    } else {
      // No cached response found
    }
  });
});

Updating Cached Content

Sometimes, we may need to update the cached content to ensure that our users always see the latest version of dynamic resources. This can be achieved by invalidating the cache and fetching the updated content from the network.

Here’s an example of how we can update the cached content:

caches.open('my-cache').then(cache => {
  cache.delete(request).then(() => {
    // Cache entry is now deleted

    // Fetch the updated content from the network
    fetch(request).then(networkResponse => {
      // Cache the updated response
      cache.put(request, networkResponse);
    });
  });
});

In this example, we first delete the cached entry using the cache.delete method. We then fetch the updated content from the network and store it in the cache using the cache.put method.

Conclusion

Dynamic content caching is an important technique for improving the performance and user experience of our web applications. The JavaScript Cache API provides a convenient way to implement dynamic caching in our applications.

In this blog post, we explored how to use the Cache API to cache dynamic content, retrieve cached content, and update the cached content when necessary. By utilizing the power of caching, we can create more responsive and efficient web applications.

Start using the Cache API in your web applications today and see the difference it makes!

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