In today’s digital world, offline browsing is becoming increasingly important for users who want to access web content without a stable internet connection. One way to achieve offline browsing is by using the JavaScript Cache API, which allows you to store and retrieve data from a cache.

Table of Contents

• Introduction to the Cache API
• Storing Data in the Cache
• Retrieving Data from the Cache
• Updating and Clearing the Cache
• Conclusion

Introduction to the Cache API

The Cache API is a part of the Service Worker API and provides a flexible way to store network requests and responses in a cache. By implementing service workers, you can intercept web requests and decide whether to retrieve the data from the cache or the network.

Storing Data in the Cache

To store data in the cache, you first need to open a cache using the caches.open() method. This method returns a promise that resolves to a specific cache object. You can then use the cache object to store responses using the cache.put() method.

Here’s an example of storing a response in the cache:

caches.open('my-cache')
  .then(function (cache) {
    cache.put('/api/data', new Response('Hello, World!'));
  });

In this example, we open a cache named “my-cache” and store a response with the URL “/api/data” and a simple “Hello, World!” text as the body.

Retrieving Data from the Cache

To retrieve data from the cache, you can use the cache.match() method. This method returns a promise that resolves to the cached response if found, or undefined if not found.

Here’s an example of retrieving data from the cache:

caches.match('/api/data')
  .then(function (response) {
    if (response) {
      // Found in cache
      return response.text();
    } else {
      // Not found in cache
      // Fetch from network
      return fetch('/api/data')
        .then(function (networkResponse) {
          // Store the response in cache
          caches.open('my-cache')
            .then(function (cache) {
              cache.put('/api/data', networkResponse.clone());
            });

          return networkResponse.text();
        });
    }
  })
  .then(function (data) {
    console.log(data);
  });

In this example, we first try to match the request URL “/api/data” with the cache. If a cached response is found, we retrieve its text and log it to the console. If the response is not found in the cache, we fetch it from the network, store it in the cache, and log its text.

Updating and Clearing the Cache

To update an existing cache, you can simply call the cache.put() method again with the updated response. The cache will automatically store the new response and overwrite the old one.

To clear a cache, you can use the cache.delete() method, which deletes a specific response from the cache.

// Update cache
caches.open('my-cache')
  .then(function (cache) {
    cache.put('/api/data', new Response('New data'));
  });

// Clear cache
caches.open('my-cache')
  .then(function (cache) {
    cache.delete('/api/data');
  });

Conclusion

The JavaScript Cache API provides a powerful way to achieve offline browsing by allowing you to store network requests and responses in a cache. By utilizing this API, users can access web content even without an internet connection. However, it’s important to note that the Cache API is only available in service workers, so make sure to build your application with service workers enabled.

For more information on the JavaScript Cache API, refer to the MDN Web Docs. #javascript #offlinebrowsing