Chris McCord, author of the Phoenix Framework, will soon release a new feature called LiveView: a way of making interactive apps without JavaScript. It's powered by WebSockets, morphdom

Phoenix LiveView is an exciting new library which enables rich, real-time user experiences with server-rendered HTML. LiveView powered applications are stateful on the server with bidrectional communication via WebSockets, offering a vastly simplified programming model compared to JavaScript alternatives. While modern JavaScript tooling enables sophisticated client applications, it often comes at an extreme cost in complexity and maintainability

https://dockyard.com/blog/2018/12/12/phoenix-liveview-interactive-real-time-apps-no-need-to-write-javascript