Html 下拉菜单在标题中不起作用

我有一个非常简单的引导头。唯一的问题是标题中的下拉菜单没有下拉。。。我将在下面发布我的代码

代码：

切换导航

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我知道要发布的代码很多，只是想确保没有遗漏任何内容。

您需要链接JQuery for下拉菜单才能工作。将其添加到bootstrap.min.js之前

在添加JQuery之后，它是这样的

<!-- Latest compiled and minified CSS -->
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css" />

<!-- Font awesome reference -->
<link rel="stylesheet" href="http://maxcdn.bootstrapcdn.com/font-awesome/4.3.0/css/font-awesome.min.css" />

<!-----add this JQuery before bootstrap.min.js----->
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.0.0-alpha1/jquery.min.js"></script>

<!-- Latest compiled and minified JavaScript -->
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/js/bootstrap.min.js"></script>

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希望这对你有帮助

您是否链接了文档中的

jquery.js

？引导jquery.js？

<nav class="navbar navbar-default navbar-fixed-top">
    <div class="container">
        <div class="navbar-header">
            <button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#navbar" aria-expanded="false" aria-controls="navbar">
                <span class="sr-only">Toggle navigation</span>
                <span class="icon-bar"></span>
                <span class="icon-bar"></span>
                <span class="icon-bar"></span>
            </button>
            <a class="navbar-brand" href="#">My Project</a>
        </div>
        <div id="navbar" class="navbar-collapse collapse">
            <ul class="nav navbar-nav">
                <li class="active"><a href="#">Home</a></li>
                <li><a href="#">Contact</a></li>
                <li runat="server" class="dropdown">
                    <a href="#" class="dropdown-toggle" data-toggle="dropdown">Dropdown<b class="caret"></b></a>
                    <ul class="dropdown-menu">
                        <li><a href="#">Menu Item 1</a></li>
                        <li><a href="#">Menu Item 2</a></li>
                        <li><a href="#">Menu Item 3</a></li>
                        <li><a href="#">Menu Item 4</a></li>
                    </ul>
                </li>
            </ul>              
        </div>
        <!--/.nav-collapse -->
    </div>
</nav>

<!-- Latest compiled and minified CSS -->
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css" />

<!-- Font awesome reference -->
<link rel="stylesheet" href="http://maxcdn.bootstrapcdn.com/font-awesome/4.3.0/css/font-awesome.min.css" />

<!-----add this JQuery before bootstrap.min.js----->
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.0.0-alpha1/jquery.min.js"></script>

<!-- Latest compiled and minified JavaScript -->
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/js/bootstrap.min.js"></script>