<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
<title></title>
</head>
<body>
<div class="box1" style="position: absolute;">
<div class="box2" style="position: fixed;">
<div class="box3"></div>
</div>
</div>
<script>
//offsetParent：复习盒子中带有定位的盒子
//复习盒子中都没有定位，返回body
//如果有，谁有返回最近哪个
var box3 = document.getElementsByClassName("box3")[0];
console.log(box3.offsetParent);
</script>
</body>
</html>
原文：http://www.cnblogs.com/sj1988/p/6594092.html