If you're going to be doing anything more complex than form validation and CSS animations on the client, you're going to need JS. If it's a constraint that ther

If you're going to be doing anything more complex than form validation and CSS animations on the client, you're going to need JS. If it's a constraint that there must only be one language then you have to use JS on the server too. Nowadays the best experience with full stack JS is a full-stack framework like Next.js, Next or the one I recommend, sveltekit. You can easily write client pages & server routes Next to each other, with all the standard client side features like components and use tried and tested JS libraries like node-postgres. It's great and is unlikely to break for years, or decades if dependencies are updated.