Add lastmod to sitemap

🐛 Bug Report

The XML sitemaps currently output loc, changefreq and priority for every url set. I would propose dropping the changefreq and priority fields, as none of the search engines use these, and instead adding the lastmod field, with the last modification date of the file.

Have you read the Contributing Guidelines on issues?

Yes.

To Reproduce

(Write your steps here:)

1. Open any DocuSaurus v2 sitemap 😃

Expected behavior

The current output would be:

<url>
        <loc>https://developer.yoast.com/features/canonical-urls/api</loc>
        <changefreq>weekly</changefreq>
        <priority>0.5</priority>
</url>

(Write what you thought would happen.)

Actual Behavior

I propose changing it to:

<url>
        <loc>https://developer.yoast.com/features/canonical-urls/api</loc>
        <lastmod>2020-04-14T11:22:05+00:00</lastmod>
</url>

Your Environment

• Docusaurus version used: v2

[jdevalk]

If this info can’t be obtained (pages might not be generated from FS files), is it better to not add the lastmod entry, or to fallback to build time (which is likely to be a recent value if the site is built often).

I would not add it then. Having it change all the time when it’s actually not changing is also not beneficial.

We agree that this date should rather be updated when the content change, but not when the code (ie the layout rendering the content etc) change?

Agreed.

[slorber]

Thanks, will do that.

About lastModified, some plugins already read git history to get the last modified date. We can enable also to hardcode it through frontmatter.

I think we should:

• call addRoute apis with lastModified: lastModifiedFrontmatter || lastModifiedGit || lastModifiedFS || undefined
• use that data when generating the sitemaps. If not available, add the date of the build?

If this info can’t be obtained (pages might not be generated from FS files), is it better to not add the lastmod entry, or to fallback to build time (which is likely to be a recent value if the site is built often).

We agree that this date should rather be updated when the content change, but not when the code (ie the layout rendering the content etc) change?