应用场景：在某些情况下我们需要将浮动布局转换成为定位布局，以实现动画效果。
我们通过给父级设置postion属性，使用offsetTop和offsetLeft获取位置后赋值
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<style>
* {
margin: 0;
padding: 0;
}
ul {
margin: 100px;
width: 500px;
height: 500px;
background-color: black;
position: relative;
}
li {
float: left;
border: 1px solid black;
width: 100px;
height: 100px;
background-color: aqua;
/* text-decoration: none; */
list-style: none;
}
</style>
</head>
<body>
<ul>
<li></li>
<li></li>
<li></li>
<li></li>
<li></li>
<li></li>
<li></li>
<li></li>
<li></li>
<li></li>
</ul>
<script>
var ali = document.getElementsByTagName("li");
var arr = [];
for (var i = 0; i < ali.length; i++) {
var obj = {
};
obj.left = ali[i].offsetLeft; //获取到的是最近的定位父级的距离位置
obj.top = ali[i].offsetTop;
arr.push(obj);
}
for (var i = 0; i < ali.length; i++) {
ali[i].style.position = "absolute";
ali[i].style.left = arr[i].left + "px";
ali[i].style.top = arr[i].top + "px";
}
</script>
</body>
</html>
