HTTPArchive
Tech Report: Consider adding Back/forward cache (bfcache) Eligibility and Speculation Rules usage per Technology
Hello everyone, I wonder if there is any appetite to add new dimensions to appreciate UX achievements across Technologies.
One is the fact that by using a particular technology, Back/forward cache eligibility can be highly influenced.
With a simple check in the HTTP Archive queries like below it's possible to measure in time how many Origins are Eligible to Back/forward cache
Back/forward cache eligibility doesn't necessarily mean that a Back Forward navigation will go through Back/forward cache but it helps to identify whether there are major blockers like usage of Cache-Control: no-store, WebSocket, Unload and other blockers.
IF(lighthouse.audits['bf-cache'].details.items IS NULL, TRUE, FALSE) as bfcache_eligible
Similarly it could be also possible to measure how many Origins using a Technologies may be adding Speculation Rules (also here, adding a rule doesn't mean usage). Example below about how to measure a presence of a Speculation Rules for Prefetch:
IF("SpeculationRulesAuthorPrefetchRule" IN (SELECT feature FROM UNNEST(features)), TRUE, FALSE) AS using_SpeculationRules_Prefetch
Looking forward to hear if others are also interested to see this kind of aspect.
There are CMSs that for legacy reasons are overusing Cache-Control: no-store for example, similarly 3P Chat Widgets that made their WebSocket implementation while others not etc.
