Let's say I have something.style.top = "Ypx", how to extract and increment that Y, if Y can be either negative or positive?

Question

Y < innerHeight

Answer 1

something.style.top = parseInt(something.style.top)+1 + "px"
Or
something.style.top = +something.style.top.slice(0,-2)+1 + "px"

Answer 2

parseFloat might be better.