Just to clarify, AngularJS refers to the (now legacy) 1st version of the framework. Unless you're maintaining an old project, there's little point in learning AngularJS now.
Angular (w/o the JS suffix) refers to version 2+, which has been a complete rewrite. How much JS should you know? Well this is what the docs say:
So first of all, you should make yourself a bit familiar with TS... while not strictly necessary, basically all resources you'll find on the internet are in TS. And then my take would be to just start with the tutorial and see if it all makes sense to you... if not, you should probably take a step back. Quite simple.