Using the JavaScript Cache API for script caching

23 Oct 2023

In modern web development, JavaScript plays a vital role in creating interactive and dynamic web applications. As web applications become more complex, it’s important to optimize performance by reducing the number of network requests. One way to achieve this is by caching scripts to avoid downloading them repeatedly. In this article, we will explore how to use the JavaScript Cache API to effectively cache scripts.

What is the Cache API
Caching Scripts with the Cache API
Retrieving Cached Scripts
Updating Cached Scripts
Clearing the Cache
Conclusion

What is the Cache API

Introduced with the Service Worker API, the Cache API provides an interface for storing and retrieving cached network resources. It allows developers to cache various types of files, including HTML, CSS, images, and, in our case, JavaScript files. The Cache API provides a simple and efficient way to store and retrieve responses from network requests.

Caching Scripts with the Cache API

To cache a script using the Cache API, first, we need to open a cache using the caches.open() method. We can provide a unique name for the cache, such as "scriptsCache".

caches.open("scriptsCache")
  .then((cache) => {
    // Cache the script
    cache.add("/path/to/script.js");
  });

In the above code snippet, we open a cache named "scriptsCache" and add the script located at /path/to/script.js to the cache using the cache.add() method.

Retrieving Cached Scripts

Once we have cached the script, we can retrieve it using the caches.match() method. This method accepts a request and returns a Promise that resolves to the matching response, if found in the cache.

caches.match("/path/to/script.js")
  .then((response) => {
    if(response) {
      // The script is cached, use it
      response.text().then((scriptContent) => {
        // Access the script content
        console.log(scriptContent);
      });
    }
  });

In the code above, the caches.match() method is used to check if the script located at /path/to/script.js is already cached. If a matching response is found, we can access the script’s content by calling response.text().

Updating Cached Scripts

The Cache API also allows us to update cached scripts. To update a script, we can simply add the updated version to the cache using the same cache name.

caches.open("scriptsCache")
  .then((cache) => {
    // Update the script
    cache.add("/path/to/updated-script.js");
  });

In the code snippet above, we open the "scriptsCache" cache and add the updated script located at /path/to/updated-script.js.

Clearing the Cache

At times, we may need to clear the entire cache, including all the cached scripts. To achieve this, we can use the caches.delete() method, which accepts the cache name as a parameter.

caches.delete("scriptsCache")
  .then((cacheDeleted) => {
    if (cacheDeleted) {
      // The cache was deleted successfully
      console.log("Cache deleted successfully");
    }
  });

The caches.delete() method is used to delete the cache with the name "scriptsCache". Once deleted, all the scripts stored in the cache will be removed.

Conclusion

Caching scripts using the JavaScript Cache API is an effective way to improve the performance of web applications by reducing network requests. By caching frequently accessed scripts, we can provide a faster and more seamless user experience. It is important to keep in mind that when updating scripts that are already cached, we need to ensure that older versions are replaced with the latest ones. With the Cache API, we have powerful tools at our disposal to efficiently manage and utilize script caching in our web applications.

Reference: MDN Web Docs - Cache

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