rel attribute for external links

[ovlb]

In the discussion of #218 @sarenji discovered that we were using malformed rel attributes on external links. I think we should reevaluate the usage of noreferrer. Using rel with this value hides Self-Defined from pages that are visited through us. Is that something we want?

Besides that, what we should add is noopener as this has a real performance benefit.

Would love to have your input which value (or combination thereof) we should use going forward.

[sarenji]

I think noreferrer/noopener only really needs to be set when the link also has target="_blank" for security and performance reasons. Some good news: rel="noreferrer" also implies rel="noopener". eslint-plugin-react has a good discussion on the spec & legacy browser support. So we just need to pick between noreferrer and noopener, and only if the link also has target="_blank".

It doesn't look like SelfDefined uses target="_blank" on its links. In that case, I'd be okay with removing the rel attribute altogether. If target="_blank" is used in the future, I don't have any strong opinions on whether to use noreferrer or noopener 😬

[tatianamac]

We can fix this; this was an error on my part. For posterity, I found this article helpful, and will place here in case this is brought up again in the future.

On another note: nofollow, for instance, might be a better replacement:

• Remove any rel links
• Add to documentation (if relevant) to avoid target="_blank"

I can make a PR for this in a little bit if we agree to this approach.

[sarenji]

That checklist sounds good to me! I don't know enough about SEO to have an opinion about nofollow.

[ovlb]

Checklist looks good, yes. I’d say the addition of nofollow makes the most sense in the definition content and further reading sections, as we may link to sources that we do not necessarily want to be associated with. It’s pretty straight forward for further reading. For the content itself less so, as we have to write a plugin for markdown-it