Question

我正在尝试向该网站添加导航栏，但是由于某些原因，它无法正常运行。我要解决的主要问题是获取下拉菜单以实际显示列表。从外观上看，菜单似乎已经展开，但是我不知道这是否与为什么它不起作用有关。目前，由于我添加的CSS，折叠后的版本只能从汉堡包菜单中打开。没有CSS，该导航栏将扩展，但立即会再次崩溃。我尝试过的事情：

我试图切换包含Bootstrap.js / css和jQuery的顺序，但这没有影响。
我也尝试过切换版本，因为我不确定什么与什么兼容，但这还没有成功。
起作用的一件事是使用旧版本的引导程序，但如果可能的话，我想使用4.0或更高版本。

我很高兴有人可以帮助我弄清楚为什么它不起作用。谢谢！

.navbar-collapse.collapse.in {
  display: block!important;
}

<!DOCTYPE html>
<html>
<head>
   <title>Title</title>


  <script
  src="https://code.jquery.com/jquery-3.2.1.min.js">
  </script>
  <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
  <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css">
  
  <link rel="stylesheet" href="index.css">

   

</head>
<body>

<nav class="navbar navbar-expand-lg navbar-light bg-light">
  <a class="navbar-brand" href="#">Navbar</a>
  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>

  <div class="collapse navbar-collapse" id="navbarSupportedContent">
    <ul class="navbar-nav mr-auto">
      <li class="nav-item active">
        <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Link</a>
      </li>
      <li class="nav-item dropdown">
        <a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
          Products
        </a>
        <div class="dropdown-menu" aria-labelledby="navbarDropdown">
          <a class="dropdown-item" href="#">Action</a>
          <a class="dropdown-item" href="#">Another action</a>
          <div class="dropdown-divider"></div>
          <a class="dropdown-item" href="#">Something else here</a>
        </div>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">About Us</a>
      </li>
    </ul>
    <form class="form-inline my-2 my-lg-0">
      <input class="form-control mr-sm-2" type="search" placeholder="Search" aria-label="Search">
      <button class="btn btn-outline-success my-2 my-sm-0" type="submit">Search</button>
    </form>
  </div>
</nav>

<div class="jumbotron">
  <h1 class="display-3">Hello, world!</h1>
  <p class="lead">This is a simple hero unit, a simple jumbotron-style component for calling extra attention to featured content or information.</p>
  <hr class="my-4">
  <p>It uses utility classes for typography and spacing to space content out within the larger container.</p>
  <p class="lead">
    <a class="btn btn-primary btn-lg" href="#" role="button">Learn more</a>
  </p>
</div>

</body>
</html>

Answer 1

那是因为您的bootstrap.js版本是3.3.7，这不是实现子菜单（在引导3上）的方式。虽然，如果您已经在使用引导程序4，则应考虑将bootstrap.js更新到4.0.0版本（并且应该使用bootstrap.js和bootstrap.css的相同版本，以避免出现意外错误（就像您刚遇到的一样。）

.navbar-collapse.collapse.in {
  display: block!important;
}

<!DOCTYPE html>
<html>
<head>
   <title>Title</title>


  <script
  src="https://code.jquery.com/jquery-3.2.1.min.js">
  </script>
  <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js"></script>
  <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css">
  
  <link rel="stylesheet" href="index.css">

   

</head>
<body>

<nav class="navbar navbar-expand-lg navbar-light bg-light">
  <a class="navbar-brand" href="#">Navbar</a>
  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>

  <div class="collapse navbar-collapse" id="navbarSupportedContent">
    <ul class="navbar-nav mr-auto">
      <li class="nav-item active">
        <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Link</a>
      </li>
      <li class="nav-item dropdown">
        <a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
          Products
        </a>
        <div class="dropdown-menu" aria-labelledby="navbarDropdown">
          <a class="dropdown-item" href="#">Action</a>
          <a class="dropdown-item" href="#">Another action</a>
          <div class="dropdown-divider"></div>
          <a class="dropdown-item" href="#">Something else here</a>
        </div>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">About Us</a>
      </li>
    </ul>
    <form class="form-inline my-2 my-lg-0">
      <input class="form-control mr-sm-2" type="search" placeholder="Search" aria-label="Search">
      <button class="btn btn-outline-success my-2 my-sm-0" type="submit">Search</button>
    </form>
  </div>
</nav>

<div class="jumbotron">
  <h1 class="display-3">Hello, world!</h1>
  <p class="lead">This is a simple hero unit, a simple jumbotron-style component for calling extra attention to featured content or information.</p>
  <hr class="my-4">
  <p>It uses utility classes for typography and spacing to space content out within the larger container.</p>
  <p class="lead">
    <a class="btn btn-primary btn-lg" href="#" role="button">Learn more</a>
  </p>
</div>

</body>
</html>

Bootstrap导航栏下拉菜单/折叠的导航栏未打开

1 个答案: