If the API supports ETags / Conditional GET, I think that would be a much simpler solution.

Just request the same call again from the server and you'll receive a 304 if it hasn't been updated.

No new code needed.

Does a 304 with Fetch have a status of OK? Reason I ask is our middleware in our redux app would treat this as a successful request and then consequently dispatch a FETCH_SUCCESS action. Re-renders would still occur.

That said, the middleware could be updated to specifically handle 304s differently.

Thanks for the idea!