(beginner) Is/are there any routing mechanism for Kotlin Javascript?

There is this Kotlin React Router Dom Wrapper which might help you.
I also just posted a thread (well, more like a blogpost) with what I learned working in Kotlin React. I didn’t use a router myself (I only made it single-paged), but you might find something useful in it: React in Kotlin/JS, What I learned (long but useful read)