html
<!DOCTYPE>
<head>
<link href="css/lianxi.css" type="text/css" rel="stylesheet">
<script type="text/javascript" src="js/jquery-3.3.1.min.js"></script>
<style>
</style>
</head>
<body>
<div class="t">
<div id="div1">
</div>
</div>
<script type="text/javascript" src="js/Untitled-1.js"></script>
</body>
</html>
css
#div1{
width:100px;
height:100px;
border-raduis:50%;
background-color:#0099FF;
}
.t{
width:800px;
height:800px;
background-color:yellow;
}
js
$(document).ready(function(){
$(".t").mousemove(function(event){
var evt = event || body.t.event;
var x=event.pageX;
var y= event.pageY;
$("#div1").css({"margin-left":x+"px","position":"absolute","top":y+"px"});
})
})