Why still make conditional GET (304) with with expires header

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Why still make conditional GET (304) with with expires header



I'm learning about web performance.



And as I know, when make request to require a resource with header: "expires" or "cache-control" that still valid, the browser'll not make a conditional GET to ask server if a resource has been modified.



So, why the browser alway make conditional GET when i make this request: https://www.debian.org/Pics/debian.png



screeshot request information





The server response is 304, so no content has been send to the client since the client already has the content/data.
– Progman
2 hours ago




1 Answer
1



Take a close look at the request headers: "Cache-Control: max-age=0".



When refreshing an URL, your browser always adds this header to make sure it's "refreshed". If you want to see your real browser's behavior, try navigating to another url then click the back button, Chrome should get the image from its cache.



I've just tried, it does!






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