> As an example, the Eleventy documentation seems to avoid using client-side JavaScript for the most part. As Eleventy supports various templating languages it provides code samples in each of the different languages. Unfortunately, it doesn’t record which language you’ve selected so if your chosen language is not the default one, you are forced to change tabs on every single code sample. A little client-side JavaScript here would make the experience so much more pleasant for users.
This may actually be an ePrivacy limitation (cookie law) not a desire to avoid JS. Persisting the setting across pages requires client size storage, which in ePrivacy countries requires either that the setting be obvious to the user that it's persisted, getting per-action consent (ex: a "preferred language" setting) or site-wide user consent (a cookie pop-up).