When JavaScript is disabled in the browser, beta features that require JavaScript are distinguished using the "This feature requires JavaScript" message in Special:Betafeatures.
With the current set of beta features, I suspect the only one that works without JavaScript is "Structured Discussion". But I see that features such as "Wikitext syntax highlighting", "Advanced Search interface" aren't marked as requiring JavaScript though they don't seem to work without it. Features such as "New wikitext mode" are correctly flagged as requiring JavaScript.
This inconsistency should be fixed.
Current Beta Features which I think need JS, but don't state it:
- New filters for edit review
- Wikitext syntax highlighting
- Advanced Search Interface
- Two column edit conflict
Current ones which I think are fine:
- New video player (stated)
- VisualEditor (stated)
- Visual differences (stated)
- Structured Discussions on user talk (doesn't need JS)
- Content Translation (stated)