JSFiddle - React, Tailwind, and code Playground

HTML

<p id="coords">0, 0</p>
<div id="aaa"></div>

CSS

#aaa{border:1px solid red; width:200px;height:300px}

JavaScript

$(document).mousemove(function(e){
    a=$('#aaa');
    l=a.offset().left;
    t=a.offset().top;
    w=a.width();
    h=a.height();
    
    x=e.pageX;y=e.pageY
    x=(x<l||x>l+w)?0:x-l;
    y=(y<t||y>t+h)?0:y-t;
    
    $('#coords').html((x&&y?x:0) +', '+ (x&&y?y:0));
});