Quick solution: getting the mouse position on an element regardless of positioning

As I was upgrading an older codebase of mine that used layerX and layerY I looked into a very succinct way of finding the current mouse position on any element regardless of its position, scrolling, padding, margin and such and I found this to work for me, so maybe it is good for you, too.

const getposition = ev => {
  let x = ev.clientX;
  let y = ev.clientY;
  let pos = ev.target.getBoundingClientRect();
  // the bitwise shift |0 rounds non-integer values down.
  // if you want to round up, use 1.
  return {
    x: x - pos.x|0,
    y: y - pos.y|0
  };
}

Here’s a codepen of it in action, and you can play with it and give it more annoying things to deal with.

See the Pen [
Get mouse position on element.](https://codepen.io/codepo8/pen/poJBQqL) by Christian Heilmann ([@codepo8](https://codepen.io/codepo8))
on [CodePen](https://codepen.io/).