实例（获取流动值案例scroll和scrollTop的运用）
<!DOCTYPE html>
<html>
<head>
<title>获取滚动值案例</title>
<link rel="icon" type="image/x-icon" href="images/2.png">
<script src="https://code.jquery.com/jquery-3.1.1.min.js"></script>
<style type="text/css">
*{margin: 0;padding: 0;}
.content{ width:100%;height:60px;
background: rgba(160,3,162,0.1);
box-shadow: 1px 3px 7px #ccc;
line-height: 60px;
position: fixed;
}
.content_2 { background: rgba(160,3,162,0.4);}
form{width: 500px;height: 35px;position: relative;margin: 0 auto;}
input{width:480px;height: 35px;border-radius: 20px;border:none;outline: none;padding-left:20px;}
button{width: 70px;height:35px;order:none;
border-top-right-radius: 20px;border-bottom-right-radius: 20px;border: none;
color: #fff;position: absolute;right:0;top:14px;
outline: none;font-weight: bold;
background: rgba(160,3,162,0.4);
}
[placeholder]{color:rgba(160,3,162,0.6)}
.pic{width: 70%;height: 580px;background: url(images/3.jpg);margin: 0 auto;}
.box{width: 70%;height:1200px;background:rgba(108,108,106,0.1);margin: 0 auto; }
</style>
</head>
<body>
<!-- 顶部导航 -->
<div class="content">
<form>
<input type="text" placeholder="# 请输入关键词 #">
<button>全网搜</button>
</form>
</div>
<!-- 轮播图 -->
<div class="pic"></div>
<!-- 页面详情 -->
<div class="box"></div>
<script>
$(function(){
//scroll事件 ：当用户流动指定的元素时触发
$(window).scroll(function(){
if($(window).scrollTop() > 60) { //流动条距窗口顶部60过后触发（隐藏导航条）
$('.content').css('display','none')
} else {
$('.content').css('display','block')
}
if($(window).scrollTop() > 580) { ////流动条距窗口顶部580过后触发（改变样式为content_2并显示）
$('.content').addClass('content_2').css('display','block')
} else {
$('.content').removeClass('content_2')
}
})
})
</script>
</body>
</html>运行实例 »
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