页面中常见返回顶部总结
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>点击回到顶部</title>
<link rel="stylesheet" type="text/css" href="static/font-awesome-4.7.0/css/font-awesome.min.css">
<link rel="icon" type="image/x-icon" href="static/images/icon.ico" />
<link rel="stylesheet" type="text/css" href="static/style4.css">
<script type="text/javascript" src="static/jquery-3.3.1.js"></script>
<script type="text/javascript">
$(function(){
$(window).scroll(
function(){
if($(window).scrollTop()>150){
$('.backTop').fadeIn(1000)
}else{
$('.backTop').fadeOut(1000)
}
})
})
</script>
</head>
<body>
<a href="" id="backTop"></a>
<div class="bcground">
<a href="#backTop"><div class="backTop"><span class="fa fa-arrow-circle-up"></span><br>返回顶部</div></a>
</div>
</body>
</html>*{margin: 0px;padding: 0px;}
.bcground{width: 1200px;height: 2000px; margin: 0px auto;background: #ccc;}
.backTop{width: 50px;height: 30px; background: #B7B4B4;position: fixed;bottom: 100px;right: 20px;font-size: 10px;text-align: center;border-radius: 2px;display: none;}
a{color: #fff;text-decoration: none;}
.fa-arrow-circle-up{margin-top: 3px;}利用if判断，以scrollTop()计算滚动条到浏览器窗口到顶部的距离为条件，实现fadeIn(）/fadeOut()效果
