JSFiddle - React, Tailwind, and code Playground

HTML

<body>
  <div id="mydiv">
  </div>
  <span id="coords">x, y</span>
</body>

CSS

#mydiv {
  width: 300px;
  height: 300px;
  background-color: #dddddd;
  border: none;
}

JavaScript

var mouseIsDown = false;

function fireThis(e) {
  if (mouseIsDown === false)
    return;

  var parentOffset = $(this).parent().offset();
  var x = e.pageX - parentOffset.left;
  var y = e.pageY - parentOffset.top;
  console.log(mouseIsDown);
  $('#coords').html(x + ', ' + y);
}

$('#mydiv').on('mousedown', function() {
  mouseIsDown = true;
});
$('#mydiv').on('mouseup', function() {
  mouseIsDown = false;
});
$('#mydiv').on('mousemove', fireThis);
$('#mydiv').on('mouseout', function() {
  mouseIsDown = false;
});