<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<style type="text/css">
*{
margin: 0;
padding: 0;
}
body{
height: 5000px;
}
#ad{
width: 100px;
height: 200px;
position: absolute;
right: 10px;
top: 50%;
}
</style>
</head>
<body>
<div id="ad">
<img src="img/IMG_4507.JPG" />
</div>
<script type="text/javascript">
var oAd = document.getElementById('ad');
function ad(){
// console.log('scroll');
// 通用解決方案
var scrollTop = document.body.scrollTop||document.documentElement.scrollTop;
var windowHeight = document.documentElement.clientHeight;
var oAdHeight = oAd.offsetHeight;
var h = (windowHeight-oAdHeight)/2+scrollTop;
// console.log(h);
oAd.style.top = h + 'px';
}
ad();
window.onresize = window.onscroll = ad;
</script>
</body>
</html>
