Change Details

Support landed in Firefox 49 (<https://bugzilla.mozilla.org/show_bug.cgi?id=1267474>). In summary (from <https://bitsup.blogspot.co.uk/2016/05/cache-control-immutable.html>) the main benefit of "immutable" (compared to a high max-age) is that **"immutable" is not bypassed when reloading a page**. Currently, regardless of max-age, browsers often ignore local cache expiry and perform If-None-Match/If-Modified-Since requests (yielding "304 Not Modified" responses for static assets). These are smaller than the "200 OK" response would have been (since browsers do remember and send E-Tag or Last-Modified headers), but are still worse than proper cache hits due to the required roundtrips for each 304 response. Impact may be limited on Chrome since Chrome, unlike Firefox, does not ignore local cache expiry for subresources. When reloading a page in Chrome, cache-miss is only enforced on the main document. (per <https://code.facebook.com/posts/557147474482256> and <https://bugs.chromium.org/p/chromium/issues/detail?id=654378>) Background: * <https://bitsup.blogspot.co.uk/2016/05/cache-control-immutable.html> * <https://www.ietf.org/mail-archive/web/httpbisa/current/msg25463.html> * <https://webplatformdaily.org/releases/2016-05-12> * <https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control> * Firefox / Launch bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1267474 * Chromium / Launch bug: https://bugs.chromium.org/p/chromium/issues/detail?id=611416

Support landed in Firefox 49 (<https://bugzilla.mozilla.org/show_bug.cgi?id=1267474>). In summary (from <https://bitsup.blogspot.co.uk/2016/05/cache-control-immutable.html>) the main benefit of "immutable" (compared to a high max-age) is that **"immutable" is not bypassed when reloading a page**. Currently, regardless of max-age, browsers often ignore local cache expiry and perform If-None-Match/If-Modified-Since requests (yielding "304 Not Modified" responses for static assets). These are smaller than the "200 OK" response would have been (since browsers do remember and send E-Tag or Last-Modified headers), but are still worse than proper cache hits due to the required roundtrips for each 304 response. Impact may be limited on Chrome since Chrome, unlike Firefox, does not ignore local cache expiry for subresources. When reloading a page in Chrome, cache-miss is only enforced on the main document. (per <https://bugs.chromium.org/p/chromium/issues/detail?id=654378>) Background: * <https://bitsup.blogspot.co.uk/2016/05/cache-control-immutable.html> * <https://www.ietf.org/mail-archive/web/httpbisa/current/msg25463.html> * <https://webplatformdaily.org/releases/2016-05-12> * <https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control> * Firefox / Launch bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1267474 * Chromium / Launch bug: https://bugs.chromium.org/p/chromium/issues/detail?id=611416

Support landed in Firefox 49 (<https://bugzilla.mozilla.org/show_bug.cgi?id=1267474>). In summary (from <https://bitsup.blogspot.co.uk/2016/05/cache-control-immutable.html>) the main benefit of "immutable" (compared to a high max-age) is that **"immutable" is not bypassed when reloading a page**. Currently, regardless of max-age, browsers often ignore local cache expiry and perform If-None-Match/If-Modified-Since requests (yielding "304 Not Modified" responses for static assets). These are smaller than the "200 OK" response would have been (since browsers do remember and send E-Tag or Last-Modified headers), but are still worse than proper cache hits due to the required roundtrips for each 304 response. Impact may be limited on Chrome since Chrome, unlike Firefox, does not ignore local cache expiry for subresources. When reloading a page in Chrome, cache-miss is only enforced on the main document. (per <https://code.facebook.com/posts/557147474482256> and <https://bugs.chromium.org/p/chromium/issues/detail?id=654378>) Background: * <https://bitsup.blogspot.co.uk/2016/05/cache-control-immutable.html> * <https://www.ietf.org/mail-archive/web/httpbisa/current/msg25463.html> * <https://webplatformdaily.org/releases/2016-05-12> * <https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control> * Firefox / Launch bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1267474 * Chromium / Launch bug: https://bugs.chromium.org/p/chromium/issues/detail?id=611416