The easiest way to manage and take control of your HTTP caching in Node.js is to include HTTP headers in your HTTP responses. In order to decide whether to cache and how to cache a response, HTTP caches typically use these headers:
- Cache-Control
This header field is used to specify directives that must be obeyed by all caching mechanisms along the request-response chain. For instance, “private”, “public”, and “max-age” are some directives commonly used in Cache-Control.
Here’s an example of how to use it in Node.js:
```
res.setHeader(‘Cache-Control’, ‘public, max-age=86400’);
```
- ETag
The ETag HTTP response header is an identifier for a specific version of a resource. It lets caches be more efficient and save bandwidth, as a web server does not need to send a full response if the content has not changed.
Here’s an example on how to use it in Node.js:
```
res.setHeader(‘ETag’, ‘your-etag-value’);
```
- Expires
The Expires HTTP response header contains the date/time after which the response is considered outdated. If there is a Cache-Control field with the max-age directive in the response, the Expires header is ignored.
Here’s an example on how to use it in Node.js:
```
res.setHeader(‘Expires’, new Date(Date.now() + 86400000).toUTCString());
```
Using these HTTP response headers, you can manipulate how HTTP caches handle your resources. However, you also need to remember that the client can set request headers such as Cache-Control: no-cache to insist for the latest version of the resources.
Lastly and importantly, it’s possible to use built-in modules such as ‘fs’ to implement caching or leverage one of the many excellent HTTP caching middle-wares for Node.js like ‘apicache’, ‘memory-cache’, etc or even reverse-proxy like NGINX or use a CDN to manage caching.
