In web development, caching is a technique used to store and reuse previously fetched data. This can improve the performance and reduce the load on the server. One way to implement caching in JavaScript is by using the Cache API, which allows you to store and retrieve requests and responses in the browser’s cache.

What is the Cache API?

The Cache API provides a programmatic interface to the browser’s HTTP cache. It enables you to cache requests and responses in a key-value store, similar to a JavaScript Map. The cache is associated with a specific origin (domain) and persists across page loads.

Getting started with the Cache API

To use the Cache API, you need to check if the browser supports it using the caches property. This property returns a promise that resolves to the CacheStorage object:

if ('caches' in window) {
  // Cache API is supported
  caches.open('my-cache').then(function(cache) {
    // Cache operations...
  });
} else {
  // Cache API is not supported
  // Handle the fallback case
}

Caching API responses

To cache an API response, you can use the fetch function to make the request and store the response in the cache:

caches.open('my-cache').then(function(cache) {
  fetch('https://api.example.com/data')
    .then(function(response) {
      cache.put('https://api.example.com/data', response);
    });
});

In this example, the response from https://api.example.com/data is stored in the cache with the same URL as the key.

Retrieving cached responses

To retrieve a cached response, you can use the match method of the Cache object:

caches.open('my-cache').then(function(cache) {
  cache.match('https://api.example.com/data')
    .then(function(response) {
      if (response) {
        // Use the cached response
      } else {
        // Fetch the response from the network
      }
    });
});

If a response is found in the cache, it will be returned; otherwise, you can make a new network request to fetch the data.

Cache expiration and invalidation

By default, the Cache API does not handle cache expiration or automatic invalidation. It’s up to you to decide when to delete or update cached responses. You can use a versioning strategy or utilize the Cache API’s methods like delete and put to control the cache contents.

Conclusion

The Cache API provides a simple and effective way to implement API response caching in JavaScript. By caching responses, you can improve the performance of your web application and reduce server load. However, it’s important to handle cache invalidation and expiration to ensure that you always have the most up-to-date data.