How to detect when XHR returns a cached resource?

Question

I\'m wondering if there is a way how to detect when a response is returned from a local cache? Is it possible?

The solution should be general and work for unconditi

Answer 1

The answer is Date header

• If date header is before send date then a response is coming from a cache.
• If date header is after date when a request was sent then a response is fresh.

e.g.

• from cache: request was sent at 11:00, response date is 10:59
• no cache: request was sent at 11:00, response date is 11:01