304 response from server code example

Example 1: 304 http status code

304 Not Modified
The HTTP 304 Not Modified client redirection response code indicates that there is no need to retransmit the requested resources. It is an implicit redirection to a cached resource. This happens when the request method is safe, like a GET or a HEAD request, or when the request is conditional and uses a If-None-Match or a If-Modified-Since header.

The equivalent 200 OK response would have included the headers Cache-Control, Content-Location, Date, ETag, Expires, and Vary.

Example 2: 304 error code

304 Not Modified is an HTTP status code that is returned to the client when the cached copy of a particular file is up to date with the server. When a client such as a browser stores something in cache, it also keeps the Last-Modified header sent from the server.