If you need to manage state and want to focus on functions instead of objects (classes), try ClojureScript - especially in combination with [DataScript](https://github.com/tonsky/datascript), an immutable database and Datalog query engine. Clojure/ClojureScript's persistent, immutable memory model makes it much nicer for reasoning about state.

Maybe I'm just a dinosaur, but I can't keep up with all the changes to JavaScript, whereas ClojureScript compiles to ECMAScript 3 and the syntax hasn't changed since its release 12 years ago.