Animation on scroll: how to affect a fixed block?

Question

JavaScript

Good day everyone! Such task:
There is a fixed menu block. When scrolling the page to a certain element, it should change its color. How to implement it?
Is there a js library (not jquery) that would solve this problem?

Answer 1

https://github.com/Prinzhorn/skrollr
excellent library
here is an example with color https://codepen.io/FezVrasta/pen/lzxbj
and with a block here prinzhorn.github.io/skrollr/examples/anchor_target.html All
you have to do is unite