Cache-Control: public, max-age=10, s-max-age=10, stale-while-revalidate=5
PHP code (forwarded “.js$” file to php script):
<? sleep(5); echo time(); exit; ?>
During cache expiration, duration of request takes additional 5 seconds, so cloudflare NEVER provides stale content while revalidation.
Removing stale-while-revalidate from cache-control header hasnt any impact on flow what mean cloudflare doesnt support this feature at all.