JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container" style="position: relative; width: 500px; height: 500px;">
    
     <div style="position: absolute; left: 50px; top: 50px;">divchild1</div>
     <div style="position: absolute; left: 100px; top: 100px;">divchild2</div>
</div>

JavaScript

var elem = document.getElementById("container");
elem.addEventListener("mousemove", onMousemove, false);

function onMousemove(event) {
    x = event.offsetX;
    y = event.offsetY;
    
    console.log("X Position: " +x);
    console.log("Y Position: " +y);
};