---
title: Custom cache
description: Store, retrieve, and remove assets from cache programmatically. Use this template to optimize performance and implement custom caching strategies.
image: https://developers.cloudflare.com/core-services-preview.png
---

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# Custom cache

Control cache programmatically. Use this template to optimize performance and implement custom caching strategies.

JavaScript

```
// Define configurable cache duration in seconds (default: 30 days)const CACHE_DURATION_SECONDS = 30 * 24 * 60 * 60;
// Define which parts of the request to include in the cache keyconst USE_PATH = true; // Include path in the cache keyconst USE_QUERY_STRING = true; // Include query string in the cache keyconst INCLUDE_HEADERS = ["User-Agent"]; // Headers to include in the cache key
export default {  async fetch(request, env, ctx) {    // Generate a custom cache key based on user preferences    const cacheKey = createCacheKey(request);    console.log(`Retrieving cache for: ${cacheKey.url}.`);
    // Access the default Cache API    const cache = caches.default;
    // Attempt to retrieve the cached response    let response = await cache.match(cacheKey);
    if (!response) {      // Cache miss: Fetch the asset from the origin      console.log(`Cache miss for: ${cacheKey.url}. Fetching from origin...`);      response = await fetch(request);
      // Wrap the origin response for caching      response = new Response(response.body, response);
      // Set Cache-Control headers to define the TTL      response.headers.set(        "Cache-Control",        `s-maxage=${CACHE_DURATION_SECONDS}`,      );      response.headers.set("x-snippets-cache", "stored");
      // Store the response in the cache      await cache.put(cacheKey, response.clone());    } else {      // Cache hit: Return the cached response      console.log(`Cache hit for: ${cacheKey.url}.`);      response = new Response(response.body, response);      response.headers.set("x-snippets-cache", "hit");
      // Optionally check if the cache should expire based on age      const ageHeader = response.headers.get("Age");      if (ageHeader && parseInt(ageHeader, 10) > CACHE_DURATION_SECONDS) {        console.log(          `Cache expired for: ${cacheKey.url}. Deleting cached response...`,        );        await cache.delete(cacheKey);        response.headers.set("x-snippets-cache", "deleted");      }    }
    // Return the response to the client    return response;  },};
/** * Function to create a custom cache key based on request properties * @param {Request} request - The incoming request object * @returns {Request} - A valid cache key based on the URL */function createCacheKey(request) {  const url = new URL(request.url); // Use the request's base URL  const cacheKey = new URL(url.origin); // Start with the origin (scheme + hostname)
  // Optionally include the path  if (USE_PATH) {    cacheKey.pathname = url.pathname;  }
  // Optionally include the query string  if (USE_QUERY_STRING) {    cacheKey.search = url.search;  }
  // Optionally include specific headers  if (INCLUDE_HEADERS.length > 0) {    const headerParts = INCLUDE_HEADERS.map(      (header) => `${header}=${request.headers.get(header) || ""}`,    ).join("&");    cacheKey.searchParams.append("headers", headerParts);  }
  // Return the constructed URL as the cache key  return new Request(cacheKey.toString(), {    method: "GET",  });}
```

```json
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```