Throwing out support for HTML-only browsers is not a prerequisite for authoring a reactive UI with JS. Using Next.js, react-static, or even plain ReactDOM’s renderToString() you can generate static HTML+CSS for your pages, which would then be hydrated and become interactive only in user agents with JS enabled. Authoring components with awareness of that, you can degrade gracefully while reaping the benefits of type checking, reusable components etc. at development stage.
No, but the moment you depend on Javascript being enabled in the client, why not get rid of as much of html as possible and use a sane language like TypeScript?
