js 监听滚动实现导航栏置顶 

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>js导航栏置顶</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }

        .nav_top {
            height: 50px;
            background-color: red;
        }

        .nav_bottom {
            height: 100px;
            background-color: yellow;
            transition: all 0.6s;
        }
    </style>
</head>

<body>
    <!-- 导航栏 -->
    <nav>
        <header class="nav_top"></header>
        <header class="nav_bottom" id="top"></header>
    </nav>
    <section style="height: 1000px;"></section>

    <!-- 监听滚动导航栏置顶 -->
    <!-- 引用jquery -->
    <script src="https://cdn.staticfile.org/jquery/1.10.2/jquery.min.js"></script>
    <script type="text/javascript">
        // 获取id是top元素的top坐标。
        var top = $("#top").offset().top;
        $(window).scroll(function () {
            if ($(window).scrollTop() >= 50) {
                $("#top").attr("style", "position:fixed;top:0;z-index:999;width:100%;height:50px;");
            } else {
                $("#top").attr("style", "");
            }
        }).trigger("scroll");      
    </script>
</body>

</html>

posted @ 2022-05-12 08:56  卟怪  阅读(167)  评论(0)  编辑  收藏  举报