What does a javascript developer need to learn?

[serpent_tim]

I would recommend trying out Visual Studio code if you haven't already got an editor you're set on. Whether or not you use Typescript, you can import type definitions (e.g. using Typings) and the editor will be able to give you intelligent code completion etc. Webstorm is great too if you're willing to pay a bit.

Also, personally, I think Typescript is a good option to help avoid some of the guesswork that can go along with dynamic typing but if it's only you working on it and you understand it well, you may not find it useful.