Most likely you know that Functional Programming (FP) is a Programming paradigm, that is, an approach to write the programs you have in mind. You have already mentioned some features of such paradigm, I am revisiting JavaScript myself (Since it was a long time since I use it) these days. And I am glad to find famous functions associated with FP, like flatMap, already available in JS. Since you already mentioned lots of these features, the only one that comes to my mind is Lazy Evaluation, which gives you the ability to work with "Infinite structures".

Perhaps you are already aware of these resources, but I will never get tired of recommending the following: * FP101x by Mr. Erik Meijer (The course is archived on edx.org but you can work your way through it). * The above is based on the outstanding book by Graham Hutton, Programming in Haskell. * And, if you can afford it in terms of time, a book from Mr. Peter Van Roy, Concepts, Techniques, and Models of Computer Programming. (There is a section devoted to FP).

Last but not least, I do love JavaScript.

Hope that helps.