jQuery.scrollTop()如何工作？
scrollTop()方法获取第一个匹配元素的滚动顶部偏移量。此方法适用于可见和隐藏元素。
示例
您可以尝试运行以下代码来学习如何使用scrollTop()方法：
<html>
<head>
<title>jQuery scrollTop() method</title>
<script src = "https://cdn.staticfile.org/jquery/3.2.1/jquery.min.js"></script>
<script>
$(document).ready(function(){
$("div.demo").scrollTop( 200 );
$("div.demo").mousemove(function () {
var top = $("div.demo").scrollTop();
$("#result").html("top offset: <span>" + top + "</span>.");
});
});
</script>
<style>
div.demo {
background:#CCCCCC none repeat scroll 0 0;
border:3px
solid #666666;
margin:5px;
padding:5px;
position:relative;
width:200px;
height:100px;
overflow:auto;
}
div.result {
margin:10px;
width:100px;
height:100px;
margin:5px;
float:left;
background-color:blue;
}
p {
margin:10px;
padding:5px;
border:2px solid #666;
width:1000px;
height:1000px;
}
</style>
</head>
<body>
<div class = "demo"><p>Hello</p></div>
<span>Scroll vertical button to see the result:</span>
<div class = "result"><span id = "result"></span></div>
</body>
</html>