The screenY read-only property of the MouseEvent interface provides the vertical coordinate (offset) of the mouse pointer in screen coordinates.
A double floating point value in pixels.
Early versions of the spec defined this as an integer referring to the number of pixels.
This example displays your mouse's coordinates whenever you trigger the mousemove event.
<p>Move your mouse to see its position.</p>
<p id="screen-log"></p>let screenLog = document.querySelector("#screen-log");
document.addEventListener("mousemove", logKey);
function logKey(e) {
screenLog.innerText = `
Screen X/Y: ${e.screenX}, ${e.screenY}
Client X/Y: ${e.clientX}, ${e.clientY}`;
}