---
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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### Tags

[ Caching ](https://developers.cloudflare.com/search/?tags=Caching) 

# 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 key

const USE_PATH = true; // Include path in the cache key

const USE_QUERY_STRING = true; // Include query string in the cache key

const 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
{"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"/directory/","name":"Directory"}},{"@type":"ListItem","position":2,"item":{"@id":"/rules/","name":"Rules"}},{"@type":"ListItem","position":3,"item":{"@id":"/rules/snippets/","name":"Cloudflare Snippets"}},{"@type":"ListItem","position":4,"item":{"@id":"/rules/snippets/examples/","name":"Snippets examples"}},{"@type":"ListItem","position":5,"item":{"@id":"/rules/snippets/examples/custom-cache/","name":"Custom cache"}}]}
```