Caching is an essential technique to improve the performance and user experience of web applications. The Cache API in JavaScript provides a way to store and retrieve responses from the cache, reducing the need for network requests.
However, one challenge with caching is controlling the size of the cache, as it can quickly grow and consume a significant amount of storage space. In this blog post, we will explore how to control the cache size using the JavaScript Cache API.
The Cache interface
The Cache API allows developers to store and retrieve network responses in a cache. The Cache interface represents a named storage area, and it provides methods to add, retrieve, and delete responses. To control the cache size, we need to manage the responses stored in the cache.
Implementing cache size control
To control the cache size, we can use a cache eviction strategy called “LRU” (Least Recently Used). With this strategy, when the cache reaches its maximum size, the least recently used responses will be automatically evicted from the cache to make room for new responses.
Here’s an example of how to implement the LRU cache eviction strategy using the JavaScript Cache API:
// Set the maximum cache size (in Bytes)
const MAX_CACHE_SIZE = 10 * 1024 * 1024; // 10MB
// Open or create a cache
caches.open('my-cache').then(cache => {
// Retrieve all the cache keys (responses)
cache.keys().then(keys => {
let currentSize = 0;
let evictIndex = 0;
// Calculate the current cache size
keys.forEach(key => {
cache.match(key).then(response => {
currentSize += response.headers.get('Content-Length');
});
});
// Evict least recently used responses until the size is within the limit
while (currentSize > MAX_CACHE_SIZE && evictIndex < keys.length) {
const key = keys[evictIndex++];
cache.delete(key).then(isDeleted => {
if (isDeleted) {
cache.match(key).then(response => {
currentSize -= response.headers.get('Content-Length');
});
}
});
}
});
});
In this example, we first set the maximum cache size to 10MB. Then, we open or create a cache named ‘my-cache’. After that, we retrieve all the cache keys (responses) and calculate the current cache size by summing the Content-Length of each response.
We then use a while loop to iterate over the cache keys and delete the least recently used responses until the current cache size is within the limit. For each deleted response, we update the current cache size accordingly.
Conclusion
Controlling the cache size is important to prevent it from growing indefinitely and consuming excessive storage space. In this blog post, we explored how to implement cache size control using the JavaScript Cache API. By using the LRU cache eviction strategy, we can automatically evict least recently used responses to make room for new ones.
By effectively managing the cache size, we can optimize the performance and storage usage of web applications, resulting in a better user experience.
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