I suggest you to go with JavaScript. From my perspective JavaScript is the language you should invest your time in. The community of javascript and lots of framework helps developer to build what they want to build in no time whether it a desktop, web, mobile based application or even you can use javascript as a backend as well. There are lot of frameworks you can start learning i suggest you to go with (react,vue) library both are easy to learn than angular which is a complete framework.

And if you want to go with python as a secondary tool then i suggest you to learn a python framework (Flask,Django).