CODEWITHSUNDEEP
node.jshttp-cachingmax-age
George Paouris
George Paouris

Reputation: 645

Client keeps requesting assets event though Cache-Control haven't expired

I have a simple Node server that sets the Cache-Control max-age to 1200 seconds and the client requests an image. Even though the 1200 seconds haven't passed, if I change the image from the server and refresh the page, the image will be downloaded again (even though the 1200 seconds haven't passed). It is supposed to read from the cache until it expires.

Here is the response header:

enter image description here

Why is this happening?

Upvotes: 1

Views: 330

Answers (1)

Always Learning
Always Learning

Reputation: 5591

When you told the browser to cache, the response header includes a validator called Last-Modified. When the browser is reloading it can include this in the request to the server in an If-Modified-Since request when for the GET or HEAD request. That will cause the server to return 304 if the item has not changed.

So it sounds like things are working as they are supposed to. The fact that you changed the file caused the server to say "yeah, this file was changed so the cache shouldn't be used. here's the latest one" because the Last-Modified value won't match.

If you want to avoid this and rely on the cache timeout even if the file changes, you could change your server to make sure that the ETag and Last-Modified values never change for these files. But I would recommend letting it act this way and allow the new file change to take its place in the cache.

See this tutorial for more details.

Upvotes: 1

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