<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
<title></title>
<style>
.box1 {
width: 300px;
height: 300px;
padding: 100px;
margin: 100px;
position: relative;
border: 100px solid #000;
background-color: pink;
}
.box2 {
width: 100px;
height: 100px;
background-color: red;
/*position: absolute;*/
/*left: 10px;*/
/*top: 10px;*/
}
</style>
</head>
<body>
<div class="box1">
<div class="box3">
<div class="box2" style="left: 10px"></div>
</div>
</div>
<script>
var box2 = document.getElementsByClassName("box2")[0];
//offsetTop和offsetLeft
console.log(box2.offsetLeft);
console.log(box2.style.left);
</script>
</body>
</html>