html - 如何在 Bootstrap 4 中添加下拉菜单？

Question

我已将我的 bootstrap 3 模板更新为 bootstrap 4 版本。现在的问题是我的导航标题中的子菜单(下拉)在 bootstrap 4 中不起作用，它在 bootstrap 3 中起作用。如何在 Bootstrap 4 中为服务列表添加子菜单？ 这是我的代码，

<a class='navbar-brand' href='#'>Start Bootstrap</a>
<button class='navbar-toggler' type='button' data-toggle='collapse' data-target='#navbarResponsive' aria-controls='navbarResponsive' aria-expanded='false' aria-label='Toggle navigation'>
  <span class='navbar-toggler-icon'></span>
</button>
<div class='collapse navbar-collapse' id='navbarResponsive'>
  <ul class='navbar-nav ml-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='#'>About</a>
    </li>
    <li class='nav-item'>
      <a class='nav-link' href='#'>Services</a>
    </li>

    <li class='nav-item'>
      <a class='nav-link' href='#'>Contact</a>
    </li>
  </ul>
</div>

Answer 1

@Dinesh Kumar，希望这对您有所帮助。我已经包含了一个 codeply project与工作代码。它获取您的代码并在您的联系人列表项之后添加以下标记:

...
      <li class="nav-item dropdown">
        <a class="nav-link dropdown-toggle" href="http://example.com" id="navbarDropdownMenuLink" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
          Dropdown link
        </a>
        <div class="dropdown-menu" aria-labelledby="navbarDropdownMenuLink">
          <a class="dropdown-item" href="#">Action</a>
          <a class="dropdown-item" href="#">Another action</a>
          <a class="dropdown-item" href="#">Something else here</a>
        </div>
      </li>
...