My intention to write this article is for introducing FP concept to someone who never touch it. So, imho the best way to introduce FP to a beginner is by using the mainstream language, and for this case I use JS.

FP is not a silver bullet, so do imperative. By knowing those 2 paradigms you can get the right tool for the right job. I also don't want to do I/O heavy application with the "purity" thing. Hence in language like Clojure, we can still doing "the side-effect" thing.