If you need to detect just any scroll then you can use this function, but you can't get the direction the user scrolls in:
function mouseWheel(){
console.log("scrolled!");
}
But again, there's no way to detect the direction they scroll.
For the middle click, in your draw() function:
if (mouseIsPressed && mouseButton === "center") {
console.log(mouseButton); // "center"
}
