JSFiddle - React, Tailwind, and code Playground

HTML

<div id="div1">aaa</div>

CSS

#div1 {
    position: absolute;
    width: 100px;
    height: 100px;
    top: 20px;
    left: 20px;
    border: 1pt red solid;
}

JavaScript

$(document).mousedrag(function(e) {
   var x = e.pageX;
   var y = e.pageY; 
    
    if((x >= X && x <= X+W) &&
       (y >= Y && y <= Y+H))
        alert("in");
});

var el = "#div1";
var W = $(el).width();
var H = $(el).height();
var X = $(el).position().left;
var Y = $(el).position().top;