Ditto for the revalidation request used in the staleWhileRevalidate strategy; see https://stackoverflow.com/questions/54305729

@addyosmani do we know yet how priority will get exposed in FetchEvents? I'm assuming it'll end up being a property on Request, but it's not clear to me from looking at the draft.

The example from the spec for making requests is

<script>
 // Critical Fetch request for article content
 fetch('/api/articles.json', { importance: 'high' }).then(/*...*/)

 // Request for related content now reduced in priority
 // reducing the opportunity for contention
 fetch('/api/related.json', { importance: 'low' }).then(/*...*/)
</script>

i.e. it gets passed in as either FetchOptions when calling fetch(), or the underlying RequestInit when constructing a Request.

That would imply that it's exposed as event.request.importance inside of a fetch event, following the model for how the other properties used in RequestInit are exposed on the underlying Request.

CC: @khempenius, who expressed some interest in this.

I approve this feature 👍

https://twitter.com/DenisTRUFFAUT/status/1133372511280869376

I think this feature is needed to make precaching a truly progressive feature of any PWA.

Right now, and under certain circumstances (e.g. poor mobile data connection and a few megs of assets to precache), precaching initially worsens the user experience and must be compensated for -- e.g. delayed service worker registration & loading screen upon service worker registration that is closed upon activation.

It look forward to the days of smarter (it's already pretty good) precaching :-)

I've posted this elsewhere, but just to reflect the most recent status on this issue: Priority Hints went through the Origin Trial process in Chrome, and did not progress past that in their current incarnation.

So we're currently blocked on implemented anything in Workbox until at least one browser ships this feature.

Folks can check https://chromestatus.com/feature/5273474901737472 and ⭐️ https://bugs.chromium.org/p/chromium/issues/detail?id=821464 for updates.

should we revisit this given that now the Request.init#priority has been supported on multiple browsers:

https://caniuse.com/?search=request.init%20priority