add Sec-CH-Prefers-Reduced-Motion content

[chrisdavidmills]

Description

This PR adds content for the Sec-CH-Prefers-Reduced-Motion header; see my research document for more details: https://docs.google.com/document/d/1ENCgZ66Jsf40iMK1yatqQLeEHu9NC07Fhd6tKlgj_Bs/edit

Motivation

Readers will want to know about this new HTTP header

Additional details

Related issues and pull requests

[github-actions[bot]]

Preview URLs

• /en-US/docs/Web/HTTP/Client_hints
• /en-US/docs/Web/HTTP/Headers/Sec-CH-Prefers-Reduced-Motion
• /en-US/docs/Web/HTTP/Headers
• /en-US/docs/Web/SVG/Element/animate

Flaws (1)

Note! 3 documents with no flaws that don't need to be listed. 🎉

URL: /en-US/docs/Web/HTTP/Headers/Sec-CH-Prefers-Reduced-Motion Title: Sec-CH-Prefers-Reduced-Motion Flaw count: 1

• bad_bcd_queries:
  • No BCD data for query: http.headers.Sec-CH-Prefers-Reduced-Motion

External URLs (1)

URL: /en-US/docs/Web/HTTP/Headers/Sec-CH-Prefers-Reduced-Motion Title: Sec-CH-Prefers-Reduced-Motion

• https://web.dev/user-agent-client-hints/ (1 time) (Note! This may be a new URL 👀)

(this comment was updated 2022-11-16 16:38:13.585928)

[chrisdavidmills]

Thanks @tomayac ! I've made a few small tweaks to your wording, and I also added in the Critical-CH header to the example, as it seems useful. Now we have to document that header too, but I'm hopefully going to be able to leave it to a future update.

[tomayac]

Thank you again. FWIW, added Critical-CH to the content backlog, so it doesn't fall through the cracks.

[hamishwillee]

HI @chrisdavidmills

This probably also needs to be added to https://developer.mozilla.org/en-US/docs/Web/HTTP/Client_hints - possibly in a new class of hint.

Note, that this doc is the MDN equivalent to https://web.dev/user-agent-client-hints/ . If you look at the two side by side you can see that the MDN version, while more up to date in terms of the headers covered is still missing some key bits of information

• cross-origin usage
• A could of real examples
• More clear highlighting of the interaction with the JavaScript API.

One day that might get to my list, but feel free to jump on it :-)

[chrisdavidmills]

Cool, thanks for the review @hamishwillee . To begin with, I've added a line about this specific classic of UA hints to the "User-agent client hints" section of the Client hints page, as they are definitely in that category. That'll be in the next commit.

[hamishwillee]

Arrrggg, unrelated but I dont think https://developer.mozilla.org/en-US/docs/Web/HTTP/Client_hints is in the sidebar. Where do you think it should go? Peer under https://developer.mozilla.org/en-US/docs/Web/HTTP/Session ?

[chrisdavidmills]

@hamishwillee nice one, these changes are looking good!

Arrrggg, unrelated but I dont think https://developer.mozilla.org/en-US/docs/Web/HTTP/Client_hints is in the sidebar. Where do you think it should go? Peer under https://developer.mozilla.org/en-US/docs/Web/HTTP/Session ?

Yes, that would make sense to me.

PS I really like client hints, and I think they are quite fun to document. Does this make me some kind of sicko? Really glad you're doing these.

No more of a sicko that I thought previously anyway ;-)

[hamishwillee]

@chrisdavidmills Excellent. Did you see the comments against https://github.com/mdn/content/pull/22266 which covers much of the same ground - and I think there are some good cross links we could add?

Most of that could be done as a post process, but one comment is relevent now: https://github.com/mdn/content/pull/22266#discussion_r1022199652 ? Specifically, because you are using Critical-CH I think you must in the example also include Vary header, and if this is the case we should also mention this in the critical hints section. Can I leave it to you to confirm?

[chrisdavidmills]

@chrisdavidmills Excellent. Did you see the comments against https://github.com/mdn/content/pull/22266 which covers much of the same ground - and I think there are some good cross links we could add?

I added the cross link to the SVG animate page from @bershanskiy 's PR — that was really useful.

Most of that could be done as a post process, but one comment is relevent now: https://github.com/mdn/content/pull/22266#discussion_r1022199652 ? Specifically, because you are using Critical-CH I think you must in the example also include Vary header, and if this is the case we should also mention this in the critical hints section. Can I leave it to you to confirm?

I've added a note to cover this, along with the header in the example. It was a real pain to track down this info, but I eventually found it in the Critical-CH spec — see https://datatracker.ietf.org/doc/html/draft-davidben-http-client-hint-reliability-00#section-3!

[hamishwillee]

Looks good to me thanks @chrisdavidmills - let's get this in!

Would be great if you can work with @bershanskiy on #22266

[chrisdavidmills]

Nice one, thanks! I think for the other PR it would just make sense to follow the same structure as my page now it has been merged...happy to help tho @bershanskiy if you need anything.