This isn’t a demos page--they are just static docs where the only interactive part is some JS to make it quicker to copy/paste. Right now these docs aren’t accessible to many reading options or search indexers since there is nothing on the page.
Setting a good example & being a good steward of the net is something docs like these could/should provide; that is to say, the author could make the static parts static & offer a <noscript> with a brief description of the interactivity the user might be missing. The docs are likely coming from dog-fooding the library, but came at the cost of making static content maximally available & providing a noscript message.