展开时如何使导航栏滚动并固定到页面顶部？答案

【问题标题】：How can I make the navbar scroll and fix to the top of the page when it is expanded?展开时如何使导航栏滚动并固定到页面顶部？
【发布时间】：2016-11-28 02:46:26
【问题描述】：

当我的导航栏被折叠时，滚动是正常的，并且当滚动经过页眉/ jumbotron 时，导航栏会固定在页面顶部。但是，当导航栏展开时（显示“一”、“二”和“三”），页面将跳过一些内容并被导航栏覆盖。如何使页面滚动/行为“正常”并允许扩展的导航栏固定到页面顶部而不跳过下面的内容？

<!DOCTYPE html>
<html>

<head>
    <title>Example</title>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <link rel="stylesheet" href="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css">
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>
    <script src="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js"></script>
    <link href="https://fonts.googleapis.com/css?family=Cabin" rel="stylesheet">
    <link href="https://fonts.googleapis.com/css?family=Lobster" rel="stylesheet">
    <script type="text/javascript">
    </script>
    <style>
        .affix {
            top: 0;
            width: 100%;
        }
        .affix + .container-fluid {
            padding-top: 70px;
        }
        nav {
            z-index: 9;
        }
        .emoji p:hover {
            text-decoration: none;
        }
    </style>
</head>

<body>
    <div class="container-fluid" style="background-color:#f64e09; color:#fff; height:200px;">
        <div class="container text-center" style="color: white;">
            <div>
                <h1 style="font-family: 'Lobster', cursive;">Website</h1> </div>
            <h1 style="font-size: 30px; font-family: 'Cabin', sans-serif;">

    </h1> </div>
    </div>
    <nav class="navbar navbar-inverse" data-spy="affix" data-offset-top="197">
        <div class="container-fluid">
            <div class="navbar-static-top">
                <button type="button" class="navbar-toggle" data-toggle="collapse" data-target="#myNavbar"> <span class="icon-bar"></span> <span class="icon-bar"></span> <span class="icon-bar"></span> </button> <a id="navId" class="navbar-brand" style="color:white;" href="#">Navbar Title</a> </div>
            <div class="collapse navbar-collapse" id="myNavbar">
                <ul class="nav navbar-nav">
                    <li><a href="#">One</a> </li>
                    <li class="active"><a href="#">Two</a> </li>
                    <li><a href="#">Three</a> </li>
                </ul>
            </div>
        </div>
    </nav>
    <!-- Start containter for everything south of navbar -->
    <div class="container-fluid">
        <div class="container" style="padding-top: 20px;">
            <h1>Content so the page scrolls</h1>
            <h1>Content so the page scrolls</h1>
            <h1>Content so the page scrolls</h1>
            <h1>Content so the page scrolls</h1>
            <h1>Content so the page scrolls</h1>
            <h1>Content so the page scrolls</h1>
            <h1>Content so the page scrolls</h1>
            <h1>Content so the page scrolls</h1>
            <h1>Content so the page scrolls</h1> </div>
    </div>
    <div class="panel panel-default" style="font-family: 'Cabin', sans-    serif;">
        <div class="panel-footer">
            <center>
                <p>This is the footer</p>
            </center>
        </div>
    </div>
</body>

</html>

【问题讨论】：

标签： javascript html css navbar affix

【解决方案1】：

您可能知道，导航栏折叠时您的内容不“跳跃”的原因是这种样式：

.affix + .container-fluid {
    padding-top: 70px;
}

但是当你扩展导航栏时，内边距保持不变，但导航栏本身变得更高了。所以，我们必须以某种方式区分这些情况。

我们可以添加一些javascript 来为<nav> 元素添加一个额外的类：

<script type="text/javascript">
    $(document).ready(function() {
        var navBar = $('#myNavbar');
        $('.navbar-toggle').click(function(e) {
            if (!navBar.is(':visible')) {
                // #myNavbar is about to be shown, add extra class to parent <nav>
                navBar.parents('nav').addClass('affix-visible-navbar');
            } else {
                // #myNavbar is about to be hidden, remove extra class from parent <nav>
                navBar.parents('nav').removeClass('affix-visible-navbar');
            }
        });
    });
</script>

并定义新的 css 类：

.affix.affix-visible-navbar + .container-fluid  {
    padding-top: 155px !important;
}

所以完整的工作解决方案将如下所示：

<!DOCTYPE html>
<html>

<head>
    <title>Example</title>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <link rel="stylesheet" href="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css">
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>
    <script src="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js"></script>
    <link href="https://fonts.googleapis.com/css?family=Cabin" rel="stylesheet">
    <link href="https://fonts.googleapis.com/css?family=Lobster" rel="stylesheet">
    <script type="text/javascript">
    </script>
    <style>
        .affix {
            top: 0;
            width: 100%;
        }
        .affix + .container-fluid {
            padding-top: 70px;
        }
        .affix.affix-visible-navbar + .container-fluid  {
            padding-top: 155px !important;
        }
        nav {
            z-index: 9;
        }
        .emoji p:hover {
            text-decoration: none;
        }
    </style>
    <script type="text/javascript">
        $(document).ready(function() {
            var navBar = $('#myNavbar');
            $('.navbar-toggle').click(function(e) {
                if (!navBar.is(':visible')) {
                    // #myNavbar is about to be shown, add extra class to parent <nav>
                    navBar.parents('nav').addClass('affix-visible-navbar');
                } else {
                    // #myNavbar is about to be hidden, remove extra class from parent <nav>
                    navBar.parents('nav').removeClass('affix-visible-navbar');
                }
            });
        });
    </script>
</head>

<body>
    <div class="container-fluid" style="background-color:#f64e09; color:#fff; height:200px;">
        <div class="container text-center" style="color: white;">
            <div>
                <h1 style="font-family: 'Lobster', cursive;">Website</h1> </div>
            <h1 style="font-size: 30px; font-family: 'Cabin', sans-serif;">

    </h1> </div>
    </div>
    <nav class="navbar navbar-inverse" data-spy="affix" data-offset-top="197">
        <div class="container-fluid">
            <div class="navbar-static-top">
                <button type="button" class="navbar-toggle" data-toggle="collapse" data-target="#myNavbar"> <span class="icon-bar"></span> <span class="icon-bar"></span> <span class="icon-bar"></span> </button> <a id="navId" class="navbar-brand" style="color:white;" href="#">Navbar Title</a> </div>
            <div class="collapse navbar-collapse" id="myNavbar">
                <ul class="nav navbar-nav">
                    <li><a href="#">One</a> </li>
                    <li class="active"><a href="#">Two</a> </li>
                    <li><a href="#">Three</a> </li>
                </ul>
            </div>
        </div>
    </nav>
    <!-- Start containter for everything south of navbar -->
    <div class="container-fluid">
        <div class="container" style="padding-top: 20px;">
            <h1>Content so the page scrolls</h1>
            <h1>Content so the page scrolls</h1>
            <h1>Content so the page scrolls</h1>
            <h1>Content so the page scrolls</h1>
            <h1>Content so the page scrolls</h1>
            <h1>Content so the page scrolls</h1>
            <h1>Content so the page scrolls</h1>
            <h1>Content so the page scrolls</h1>
            <h1>Content so the page scrolls</h1> </div>
    </div>
    <div class="panel panel-default" style="font-family: 'Cabin', sans-    serif;">
        <div class="panel-footer">
            <center>
                <p>This is the footer</p>
            </center>
        </div>
    </div>
</body>

</html>

当然，如果您要更改 #myNavbar 元素（例如添加/删除项目），则必须调整 .affix.affix-visible-navbar + .container-fluid {} 中的填充

【讨论】：

我做了，但它没有显示，因为我太新用户了。
嘿，我还有一个关于这个问题的后续问题。你能帮帮我吗？
@user3376899，当然，什么问题？