What code to scrollwheel zoom with point of focus at mouse cursor tip ?

Math for the zooming part would look something like this

var percentY

var percent X

const scaleAmtY = WhateverYouWantThisNumberToBe

const scaleAmtX = WhateverYouWantThisNumberToBe

percentY = ((mouseY - stage.height)/stage.height)*100

percentX = ((mouseX - stage.width)/stage.width)*100

function thisFunctionZoomsIn (e:MouseEvent):Void{

     nameOfImage.scale.x += scaleAmtX

     nameOfImage.scale.y += scaleAmtY

     nameOfImage.x -= (scaleAmtX * percentX)

     nameOfImage.y -= (scaleAmtY * percentY)

}

Now again, This is not written in code. this is pseudo code but its prety close to code. you may have to tweek things a bit.

Also, I would guess the event listner looks something like this

stage.addEventListener(Mouse.SCROLL_UP, thisFunctionZoomsIn);

But im just guessing. I can never remember the right formula for setting up event listeners without looking at one that ive written before and that was off the top of my head. But I hope this helps.