Categories: From Zero to Infinity

There are functional leanings in JS coming about, but I don't think there is much Category Theory. It's not that you aren't capable of using it that way... its that you're not bound to anything in JS, so your assurances aren't held.

Promises bring somewhat easy to use monads. Functions are first class and with ES2016? get a pretty slick syntax°.

JavaScript is written in a functional style by Functional Programmers, so the ideas are definitely out there in the community.

°(which combines nicely with object/array destructuring and shorthand object creation)