此返回顶部用的JQ插件，所以必须先引入jquery.js
代码复制粘贴即可使用
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
<!-- 引入JQ -->
<script src="jquery.min.js"></script>
</head>
<style type="text/css">
body {
background: skyblue;
}
.btn {
color: #000;
margin: 1500px auto 500px;
}
</style>
<body>
<div class="bg">
<div class="btn">
我叫按钮
</div>
</div>
<script>
$(".btn").click(function () {
$("html,body").animate({ scrollTop: 0 }, 500);
});
</script>
</body>
</html>
