Most resources delivered by Findologic via CDN have a long cache lifetime of 24 hours. This is in line with Google's recommendations for the use of third-party resources to optimise performance for the user.
Excluded from this cache setting are the Javascript files autocomplete.js/main.js, since with a cache setting of 24 hours, updates would only be visible live after this time. The cache setting for these files was set to one second in order to guarantee the fastest possible implementation of updates. The fact that there is no alternative to the shortest possible cache life can be seen, for example, in the Google Tag Manager, which handles this in exactly the same way and is even warned by Google Pagespeed Insights.
In order to optimise loading times, Findologic uses a mechanism called ETag for the Javascript files mentioned.
Each time a page is accessed, the browser sends a request to the Findologic CDN with the hash (a unique signature calculated from the content of the file) of the autocomplete.js/main.js, which is in the cache.
If the CDN has the same hash (and the file is therefore unchanged), the content of the file is not returned, only the HTTP header. The response is then only about 204 bytes in size.
Only if the hash differs from the hash in the cache (and the file on the server has thus changed), is the complete file sent back.