<!DOCTYPE html>
<html lang="zh-cn">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Title</title>
<link rel="stylesheet" type="text/css" href="">
<link rel="stylesheet" href="../css/bootstrap.min.css">
<link rel="stylesheet" href="../css/common.css">
<style type="text/css">
.top-title {
background:#e74c3c;
color:white;
font-size:24px;
padding:5px;
text-align:center;
position: fixed;
left:0;
top:0;
width:100%;
transition: top .5s;
}
.hiddened {
top: -90px;
}
.showed {
top:0;
z-index: 9999;
}
.margint {
height: 1500px;
background-color: red;
}
</style>
</head>
<body>
<div class="top-title">这是顶部导航条</div>
<div class="margint">
<p>滚动看效果</p>
<p>滚动看效果</p>
<p>滚动看效果</p>
</div>
<script src="../js/jquery.min.js"></script>
<script type="text/javascript">
$(function(){
var winHeight = $(document).scrollTop();
$(window).scroll(function() {
var scrollY = $(document).scrollTop();// 获取垂直滚动的距离，即滚动了多少
if (scrollY > 550){ //如果滚动距离大于550px则隐藏，否则删除隐藏类
$('.top-title').addClass('hiddened');
}else {
$('.top-title').removeClass('hiddened');
}
if (scrollY > winHeight){ //如果没滚动到顶部，删除显示类，否则添加显示类
$('.top-title').removeClass('showed');
}
else {
$('.top-title').addClass('showed');
}
});
});
</script>
</body>
</html>
