My interpretation of what Retozi is saying is that CS just means that in addition to understanding JS, including ES6, you need to be familiar with all the different ways things can be done in CS.
I tend to agree, especially as JS is becoming an improving with each release.
What I'd like to see going forward is JS continuing to add selective sugar as is in CS, but also add functionality that makes going into a new fresh JS codebase and making sense of it easier. That side of things is less about CS, and more about the sorts of ideas you see in Dart and TypeScript.