The JavaScript Cache API provides a simple way to cache resources like files, images, or even API responses in the user’s browser. This can significantly improve the speed and performance of web applications by reducing the number of network requests and enabling offline support.
Table of Contents
- Cache API Overview
- Checking if a Resource is Cached
- Retrieving a Cached Resource
- Handling Cache Miss
- Conclusion
Cache API Overview
The Cache API allows you to create named caches and store resources in them using the CacheStorage interface. To retrieve resources from a cache, you first need to check if the resource is cached and then retrieve it.
Checking if a Resource is Cached
To determine if a resource is cached, you can use the cache.match(request) method. This method takes a Request object as a parameter and returns a Promise that resolves to the matching response if the resource is found in the cache. Otherwise, it resolves to undefined.
Here’s an example of how to check if an image is cached:
if ('caches' in window) {
const url = '/path/to/image.jpg';
const request = new Request(url);
caches.open('myCache')
.then(cache => {
cache.match(request)
.then(response => {
if (response) {
// Resource exists in cache
// Handle the cached response
} else {
// Resource is not cached
// Make a network request
}
});
});
}
Retrieving a Cached Resource
Once you’ve determined that a resource is cached, you can retrieve it using the response.clone() method. This method creates a clone of the response, allowing you to access the cached resource without modifying the original response.
Here’s an example of how to retrieve a cached image resource:
if ('caches' in window) {
const url = '/path/to/image.jpg';
const request = new Request(url);
caches.open('myCache')
.then(cache => {
cache.match(request)
.then(response => {
if (response) {
response.clone()
.then(cachedResponse => {
// Use the cached response
});
} else {
// Resource is not cached
// Make a network request
}
});
});
}
Handling Cache Miss
If a resource is not found in the cache, you can handle the cache miss by making a network request and storing the response in the cache for future use. You can use the cache.put(request, response) method to store the response in the cache.
Here’s an example of how to handle a cache miss and store the response in the cache:
if ('caches' in window) {
const url = '/path/to/image.jpg';
const request = new Request(url);
caches.open('myCache')
.then(cache => {
cache.match(request)
.then(response => {
if (response) {
response.clone()
.then(cachedResponse => {
// Use the cached response
});
} else {
// Resource is not cached
fetch(request)
.then(networkResponse => {
cache.put(request, networkResponse.clone())
.then(() => {
// Use the network response
});
});
}
});
});
}
Conclusion
The JavaScript Cache API provides a convenient way to cache and retrieve resources in the browser, improving the speed, performance, and offline capabilities of web applications. By using the methods provided by the API, you can easily check if a resource is cached, retrieve it from the cache, and handle cache misses by making network requests and storing the responses in the cache.
Cache responsibly, and remember to clear outdated or unnecessary resources from the cache to ensure your web application stays up-to-date and efficient.
References: