吸顶效果只需五行代码

来源：互联网发布：js获取指定日期编辑：程序博客网时间：2024/06/09 17:59

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<style>
*{
margin: 0;
padding: 0;
}
body{
height: 2000px;
background-image: linear-gradient(-180deg, #15f09d 0%, #25A0FF 50%, #fca72b 100%);
}
#wrap{
background-color: rgba(0,0,0,0.2);
width: 100%;
height: 100px;
margin-top: 100px;
}
#wrap[data-fixed="fixed"]{
position: fixed;
top:0;
left: 0;
margin: 0;
}
</style>
</head>
<body>
<div id="wrap"></div>
</body>
<script>
var obj = document.getElementById("wrap");
var ot = obj.offsetTop;
document.onscroll = function () {
var st = document.body.scrollTop || document.documentElement.scrollTop;
obj.setAttribute("data-fixed",st >= ot?"fixed":"");
}

/*封装*/
function ceiling(obj) {
var ot = obj.offsetTop;
document.onscroll = function () {
var st = document.body.scrollTop || document.documentElement.scrollTop;
/*
* 给obj添加一个自定义属性。className可能会影响原有的class
* 三元运算使代码更简洁
*/
obj.setAttribute("data-fixed",st >= ot?"fixed":"");
}
}

/*调用*/
window.onload = function () {
/*获取导航对象*/
var wrap = document.getElementById("wrap");
ceiling(wrap) /*调用吸顶函数 */
};
</script>
</html>

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