Support full sitemap spec in sitemap metadata route

[LuudJanssen]

Goals

Let the sitemap metadata route allow adding all properties described by the specification.

Non-Goals

It is mentioned in the docs that multi sitemap files are WIP and will be added later, so I consider this out-of-scope for now, making this feature request low hanging fruit.

Background

Currently, only the loc and lastmod properties of a url in the generated sitemap, generated by a sitemap metadata route (/app/sitemap.ts) are supported. However, the spec also defines changefreq and priority as possible attributes.

When using the sitemap metadata routes in a commercial project I was surprised to find these attributes not supported.

Proposal

Add the priority and changefreq attributes to the sitemap entries for the sitemap metadata routes.

A possible additional feature could be the automatic escaping of URL's in the generated XML, also described by the spec.

[LuudJanssen]

On a slightly more critical note, I'd like to ask why these properties weren't added in the first place. It feels to me like the feature shouldn't have been released when support is still very limited. Making the sitemaps fully spec compliant also doesn't feel like a big thing to add, making me feel like the dev team just forgot to read the specification.

Don't get me wrong, loving the feature, just wanted to mention my disappointment due to the lack of attention to detail. Of course, given there's no good reason to omit these properties from the (first) release.

[LuudJanssen]

I opened a PR for the addition of the attributes. Since it was a small change, I didn't wait for confirmation from the Next.js team to make it easy for them to just accept the PR instead of doing the whole discussion.

I didn't add the URL escaping, because it could possibly result in backwards incompatible changes.

[stephtr]

This is actually not the only missing part. There should for example also be a way to define alternative versions, see Google Search Central docs on that, although that's not standard.

[iljamulders]

Also missing:
https://developers.google.com/search/docs/specialty/international/localized-versions#sitemap

[stephtr]

Thanks, that's the link I actually wanted to paste.

[ozgur-shape]

I can't believe those pieces are missing. Sitemaps are a critical part of a website. This will effect us very badly. 😞

[hungcrush]

how's it going on?.....

[sjaanus]

It is now supported from v13.4.5