In modern web development, caching is a crucial technique for improving performance and reducing the load on network resources. The JavaScript Cache API provides a convenient way to cache network requests and serve them when needed. However, there may be scenarios where the cached data is outdated or the network is slow. In such cases, implementing cache fallbacks with a network timeout can provide a better user experience. In this blog post, we will explore how to implement cache fallbacks with a network timeout using the JavaScript Cache API.

Table of Contents

• Introduction
• Caching with the Cache API
• Implementing Cache Fallbacks
• Setting a Network Timeout
• Conclusion

Introduction

Caching is the process of storing the response of a network request for future use. This helps in reducing the number of network requests and improves the overall performance of a web application. The Cache API provides a way to programmatically store and retrieve network responses in the browser’s cache.

Caching with the Cache API

To cache a network request using the Cache API, you can use the cache method available on the CacheStorage object. Here’s an example:

// Open the cache storage
caches.open('my-cache').then(function(cache) {
  // Make a network request
  fetch('https://api.example.com/data')
    .then(function(response) {
      // Cache the response
      cache.put('https://api.example.com/data', response);
    });
});

In the above example, we open the cache storage using the caches.open method and then make a network request using the fetch API. Once the response is received, we cache it using the cache.put method.

Implementing Cache Fallbacks

To implement cache fallbacks, we need to check if the requested resource is available in the cache. If it is, we can serve it immediately. Otherwise, we fallback to making a network request and cache the response for future use. Here’s an example:

// Check if the requested resource is available in cache
caches.match(request).then(function(response) {
  if (response) {
    // Serve the cached response
    return response;
  }

  // Fallback to making a network request
  return fetch(request).then(function(networkResponse) {
    // Cache the network response
    caches.open('my-cache').then(function(cache) {
      cache.put(request, networkResponse.clone());
    });

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

In the above example, we use the caches.match method to check if the requested resource is available in the cache. If it is, we serve the cached response. Otherwise, we fallback to making a network request using the fetch API. Once the network response is received, we cache it using the cache.put method.

Setting a Network Timeout

To implement a network timeout, we can use the Promise.race method to race between the cache lookup and the network request. If the cache lookup takes longer than the specified timeout, we can fallback to the network request. Here’s an example:

// Set a network timeout
const timeoutPromise = new Promise(function(resolve, reject) {
  setTimeout(reject, 5000); // Reject after 5 seconds
});

// Implement cache fallbacks with a network timeout
Promise.race([caches.match(request), fetch(request), timeoutPromise])
  .then(function(response) {
    if (response) {
      // Serve the response from cache or network
      return response;
    }

    // Handle the error when the network request times out
    throw new Error('Network request timed out');
  })
  .catch(function(error) {
    // Handle errors
    console.error(error);
  });

In the above example, we create a timeoutPromise to reject after a specified timeout period. We then use Promise.race to race between the cache lookup, the network request, and the timeout promise. If a response is available from either the cache or the network, we serve it. Otherwise, we handle the error when the network request times out.

Conclusion

In this blog post, we explored how to implement cache fallbacks with a network timeout using the JavaScript Cache API. Caching network requests and serving them when needed can greatly improve the performance of your web application. By implementing cache fallbacks with a network timeout, you can ensure that your application provides a better user experience even in scenarios where the cached data is outdated or the network is slow.