chore: Move mdnsidebar into front matter

[bsmth]

Description

There are leftovers in this section that we should clean up.
Using front matter in all /mdn pages instead of macro has the side-effect that the page content should be updated, too.

Updating templates to use front matter for non-parameterized sidebars, this will likely be the default going forward.

Motivation

Fewer macros embedded in prose and page layout / type defined in front matter.

Related issues and pull requests

• chore: Use front matter for learn sidebar #39065

[github-actions]

Preview URLs (17 pages)

• /en-US/docs/MDN/Writing_guidelines/Howto/JSON_Structured_data
• /en-US/docs/MDN/Writing_guidelines/Learning_content
• /en-US/docs/MDN/Writing_guidelines/Page_structures/Page_types/API_constructor_subpage_template
• /en-US/docs/MDN/Writing_guidelines/Page_structures/Page_types/API_event_subpage_template
• /en-US/docs/MDN/Writing_guidelines/Page_structures/Page_types/API_landing_page_template
• /en-US/docs/MDN/Writing_guidelines/Page_structures/Page_types/API_method_subpage_template
• /en-US/docs/MDN/Writing_guidelines/Page_structures/Page_types/API_property_subpage_template
• /en-US/docs/MDN/Writing_guidelines/Page_structures/Page_types/ARIA_Page_Template
• /en-US/docs/MDN/Writing_guidelines/Page_structures/Page_types/CSS_function_page_template
• /en-US/docs/MDN/Writing_guidelines/Page_structures/Page_types/CSS_module_landing_page_template
• /en-US/docs/MDN/Writing_guidelines/Page_structures/Page_types/CSS_property_page_template
• /en-US/docs/MDN/Writing_guidelines/Page_structures/Page_types/CSS_selector_page_template
• /en-US/docs/MDN/Writing_guidelines/Page_structures/Page_types/Glossary_page_template
• /en-US/docs/MDN/Writing_guidelines/Page_structures/Page_types/HTML_element_page_template
• /en-US/docs/MDN/Writing_guidelines/Page_structures/Page_types/HTTP_header_page_template
• /en-US/docs/MDN/Writing_guidelines/Page_structures/Page_types/Page_type_key
• /en-US/docs/MDN/Writing_guidelines/Page_structures/Page_types/SVG_element_page_template

Flaws (3)

Note! 14 documents with no flaws that don't need to be listed. 🎉

URL: /en-US/docs/MDN/Writing_guidelines/Learning_content
Title: Learn web development writing guidelines
Flaw count: 1

• broken_links:
  • /en-US/docs/Learn_web_development/Core/Structuring_content/HTML_images/Test_your_skills:_HTML_images is a redirect

---

URL: /en-US/docs/MDN/Writing_guidelines/Page_structures/Page_types/CSS_function_page_template
Title: CSS function page template
Flaw count: 1

• macros:
  • Macro produces link /en-US/docs/Web/HTML/Element/dl which is a redirect

---

URL: /en-US/docs/MDN/Writing_guidelines/Page_structures/Page_types/Page_type_key
Title: The page-type front matter key
Flaw count: 1

• broken_links:
  • /en-US/docs/Learn_web_development/Extensions/Forms/Test_your_skills:_Basic_controls is a redirect

External URLs (2)

URL: /en-US/docs/MDN/Writing_guidelines/Howto/JSON_Structured_data
Title: How to use structured data

• https://github.com/w3c/browser-specs (1 time) (Note! This may be a new URL 👀)

---

URL: /en-US/docs/MDN/Writing_guidelines/Page_structures/Page_types/ARIA_Page_Template
Title: ARIA page template

• https://w3c.github.io/aria/ (1 time) (Note! This may be a new URL 👀)

(comment last updated: 2025-04-28 09:53:32)

[Josh-Cena]

I think we should remove this (and the one in SVG element). Elements don't make sense to be secure-context-only. And then we can remove the whole "You should update or delete the following macros according to the advice below:" part.

[hamishwillee]

Yes ^^^

[bsmth]

done in 8c34575

[hamishwillee]

Just "FWIW", we no longer need to include sidebar in the name if we're always referencing a sidebar. I.e. this would have been better as

sidebar: mdn

It made sense for macros since we had macros with different purposes.

I do much prefer this approach!

[bsmth]

Just "FWIW", we no longer need to include sidebar in the name if we're always referencing a sidebar. I.e. this would have been better as

sidebar: mdn

Yeah this is really leftovers due to migrating everything from Yari land, naming was kept so existing sidebars worked in the new world. I think we've broken that convention in some cases (like in the Privacy section -> #38269) - and totally agree this is much nicer not to have to duplicate 'sidebar' if possible :)

[bsmth]

Thanks, both! I'm going to merge now to get the changes in, but I think we can revisit the templates in general. I don't really like stuffing everything into a note block in the top of the page, and there's a lot of duplication. Compared to https://pr39274.review.mdn.allizom.net/en-US/docs/MDN/Writing_guidelines/Page_structures/Page_types/ARIA_Page_Template which is a bit easier to read, that's an improvement, IMO. Or we can look at actual templating that rari can consume / produce.