Bootstrap 4：下拉菜单在屏幕右侧关闭

我似乎无法获得下拉菜单项以不离开页面。我尝试了BS3的一些功能，但它们似乎不起作用。我不确定是否是因为ml-auto。（忽略if-else语句）

这是CodePen：

<div class="container-fluid">
  <nav class="navbar fixed-top navbar-toggleable-md navbar-inverse" style="background-color: #3c763d!important;">

    <button class="navbar-toggler navbar-toggler-right navbar-toggler-custom" type="button" data-toggle="collapse" data-target="#searchNav" aria-controls="searchav" aria-expanded="false" aria-label="Toggle navigation">
      <span class="navbar-toggler-icon"></span>

    </button>

    <button class="navbar-toggler navbar-toggler-right" type="button" data-toggle="collapse" data-target="#navbarNav" aria-controls="navbarNav" aria-expanded="false" aria-label="Toggle navigation">
      <span class="navbar-toggler-icon"></span>

    </button>

    <!-- <button class="navbar-toggler navbar-toggler-right" type="button" data-toggle="collapse" data-target="#navbarToggleExternalContent" aria-controls="navbarToggleExternalContent" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
    </button> -->

    <div id="logo">
      <a class="navbar-brand" href="/">Company</a>
    </div>

    <div class="collapse navbar-collapse" id="searchNav">
      <ul class="navbar-nav mx-auto">

        <form action="/search" class="form-inline">
          <input class="form-control mr-sm-2" id="keyword" name="keyword" :value='keyword' type="text" placeholder="Search for jobs" />
          <!-- <div class="input-group"> -->

          <input class="form-control mr-sm-2" id="location" name="location" :value='location' type="text" placeholder="Location" />
          <!-- <button class="btn btn-secondary" type="button">Find Jobs</button> -->
          <!-- </span> -->
          <!-- </div> -->

          <button class="btn btn-secondary my-2 my-sm-0" type="submit">Find Jobs</button>
        </form>

      </ul>
    </div>
    <div class="collapse navbar-collapse" id="navbarNav">

      <ul class="navbar-nav ml-auto">
        <li class="nav-item"><a href="/post" class="nav-link"><strong>Post Job</strong></a></li>

        <div class="hidden-lg-up">

          <li v-if="!user_logged" class="nav-item">
            <a v-if="!user_logged" href="/signup" class="nav-link"><strong>Register</strong></a>
          </li>

          <li v-if="user_logged && user_type === 'user'" class="nav-item">
            <a v-if="user_logged && user_type === 'user'" href="/profile" class="nav-link"><strong>Profile</strong></a>
          </li>

          <li v-if="user_logged && user_type === 'user'" class="nav-item">
            <a v-if="user_logged && user_type === 'user'" href="/applied" class="nav-link"><strong>My Jobs</strong></a>
          </li>

          <li v-if="user_logged && user_type === 'user'" class="nav-item">
            <a v-if="user_logged && user_type === 'user'" href="/searches" class="nav-link"><strong>My Searches</strong></a>
          </li>

          <li v-if="user_logged && user_type === 'company'" class="nav-item">
            <a v-if="user_logged && user_type === 'company'" href="/dashboard" class="nav-link"><strong>Employer Dashboard</strong></a>
          </li>

          <li v-if="!user_logged" class="nav-item">
            <a v-if="!user_logged" href="/login" class="nav-link"><strong>Login</strong></a>
          </li>

          <li v-if="user_logged" class="nav-item">
            <a v-if="user_logged" href="/logout" class="nav-link"><strong>Logout</strong></a>
          </li>
        </div>

        <div class="hidden-md-down">
          <li class="nav-item dropdown">
            <a class="nav-link dropdown-toggle" href="/" id="navbarDropdownMenuLink" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
              <strong>Account</strong>
            </a>
            <div class="dropdown-menu" aria-labelledby="navbarDropdownMenuLink">

              <!-- <li v-if="!user_logged" class="nav-item"> -->
              <a v-if="!user_logged" href="/signup" class="dropdown-item"><strong>Register</strong></a>
              <!-- </li> -->

              <!-- <li v-if="user_logged && user_type === 'user'" class="nav-item"> -->
              <a v-if="user_logged && user_type === 'user'" href="/profile" class="dropdown-item"><strong>Profile</strong></a>
              <a v-if="user_logged && user_type === 'user'" href="/applied" class="dropdown-item"><strong>My Jobs</strong></a>
              <a v-if="user_logged && user_type === 'user'" href="/searches" class="dropdown-item"><strong>My Searches</strong></a>

              <!-- </li> -->

              <!-- <li v-if="user_logged && user_type === 'company'" class="nav-item"> -->
              <a v-if="user_logged && user_type === 'company'" href="/dashboard" class="dropdown-item"><strong>Employer Dashboard</strong></a>
              <!-- </li> -->

              <!-- <li v-if="!user_logged" class="nav-item"> -->
              <a v-if="!user_logged" href="/login" class="dropdown-item"><strong>Login</strong></a>
              <!-- </li> -->

              <!-- <li v-if="user_logged" class="nav-item"> -->
              <a v-if="user_logged" href="/logout" class="dropdown-item">
                <div class="dropdown-divider"></div>
                <strong>Logout</strong>
              </a>
              <!-- </li> -->
            </div>

          </li>
        </div>

      </ul>
    </div>
  </nav>

</div>

Bootstrap已经内置了它：请参阅菜单对齐。只需将dropdown-menu-right类添加到dropdown-menudiv中即可。

<div class="dropdown-menu dropdown-menu-right">

工作示例：（打开整页）

<link href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.5.0/css/bootstrap.min.css" rel="stylesheet" />
<nav class="navbar navbar-expand-xl navbar-dark bg-primary">

  <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>

  <a class="navbar-brand" href="#">Company</a>

  <div class="collapse navbar-collapse" id="navbarSupportedContent">
    <form action="#" class="form-inline my-2 my-lg-0">
      <input class="form-control mr-sm-2" id="keyword" name="keyword" :value='keyword' type="text" placeholder="Search for jobs" />
      <input class="form-control mr-sm-2" id="location" name="location" :value='location' type="text" placeholder="Location" />
      <button class="btn btn-secondary my-2 my-sm-0" type="submit">Find Jobs</button>
    </form>

    <ul class="navbar-nav mr-auto">
      <li class="nav-item">
        <a href="#" class="nav-link active">
          <strong>Post Job</strong>
        </a>
      </li>
      <li class="nav-item">
        <a href="#" class="nav-link">
          <strong>Register</strong>
        </a>
      </li>
      <li class="nav-item">
        <a href="#" class="nav-link">
          <strong>Profile</strong>
        </a>
      </li>
      <li class="nav-item">
        <a href="#" class="nav-link">
          <strong>My Jobs</strong>
        </a>
      </li>
      <li class="nav-item">
        <a href="#" class="nav-link">
          <strong>My Searches</strong>
        </a>
      </li>
      <li class="nav-item">
        <a href="#" class="nav-link">
          <strong>Employer Dashboard</strong>
        </a>
      </li>
      <li class="nav-item">
        <a href="#" class="nav-link">
          <strong>Login</strong>
        </a>
      </li>
      <li class="nav-item">
        <a href="#" class="nav-link">
          <strong>Logout</strong>
        </a>
      </li>
    </ul>

    <ul class="navbar-nav">
      <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">
          <strong>Account</strong>
        </a>
        <div class="dropdown-menu dropdown-menu-right" aria-labelledby="navbarDropdown">
          <a class="dropdown-item">
            <strong>Register</strong>
          </a>
          <a href="#" class="dropdown-item">
            <strong>Profile</strong>
          </a>
          <a href="#" class="dropdown-item">
            <strong>My Jobs</strong>
          </a>
          <a href="#" class="dropdown-item">
            <strong>My Searches</strong>
          </a>
          <a href="#" class="dropdown-item">
            <strong>Employer Dashboard</strong>
          </a>
          <a href="#" class="dropdown-item">
            <strong>Login</strong>
          </a>
          <a href="#" class="dropdown-item">
            <div class="dropdown-divider"></div>
            <strong>Logout</strong>
          </a>
        </div>
      </li>
    </ul>
  </div>
</nav>

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/2.4.2/umd/popper.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.5.0/js/bootstrap.min.js"></script>

在样式表中，.dropdown-menu更改left: 0;为right: 0;。

为了使那些在谷歌搜索时偶然发现此问题但正在使用反应的人受益，被接受的答案（虽然正确）不会为您解决问题。当您手动将其添加到className时，React会忽略“ dropdown-menu-right”。相反，将您的代码更新到下面，即可正确设置相同的类。

对于javascript

<DropdownMenu right>

对于打字稿

<DropdownMenu right={true}>

当我搜索该问题时，将其放在此线程出现的位置，花了我相当长的时间才能弄清楚在反应（reactstrap）中引导4的正确解决方案。

我正在查看您的代码，我认为已接受的答案解决了另一个问题。如果菜单移动到页面的左侧或右侧而不是按钮的下方，那是因为您缺少父类，.btn-group并且您.dropdown-toggle和.dropdown-menu类似乎在错误的元素上。这是Bootstrap 4文档中最基本的示例。

<div class="btn-group">
  <button type="button" class="btn btn-secondary dropdown-toggle" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
    Right-aligned menu
  </button>
  <div class="dropdown-menu dropdown-menu-right">
    <button class="dropdown-item" type="button">Action</button>
    <button class="dropdown-item" type="button">Another action</button>
    <button class="dropdown-item" type="button">Something else here</button>
  </div>
</div>

我只浏览了一小段代码，但最后在大屏幕上出现下拉菜单时，我专注于此。

 <li class="nav-item dropdown"> <!--- change this line --->
            <a class="nav-link dropdown-toggle" href="/" id="navbarDropdownMenuLink" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
              <strong>Account</strong>
            </a>
            <div class="dropdown-menu" aria-labelledby="navbarDropdownMenuLink">

              <!-- <li v-if="!user_logged" class="nav-item"> -->
              <a v-if="!user_logged" href="/signup" class="dropdown-item"><strong>Register</strong></a>
              <!-- </li> -->

              <!-- <li v-if="user_logged && user_type === 'user'" class="nav-item"> -->
              <a v-if="user_logged && user_type === 'user'" href="/profile" class="dropdown-item"><strong>Profile</strong></a>
              <a v-if="user_logged && user_type === 'user'" href="/applied" class="dropdown-item"><strong>My Jobs</strong></a>
              <a v-if="user_logged && user_type === 'user'" href="/searches" class="dropdown-item"><strong>My Searches</strong></a>

              <!-- </li> -->

              <!-- <li v-if="user_logged && user_type === 'company'" class="nav-item"> -->
              <a v-if="user_logged && user_type === 'company'" href="/dashboard" class="dropdown-item"><strong>Employer Dashboard</strong></a>
              <!-- </li> -->

              <!-- <li v-if="!user_logged" class="nav-item"> -->
              <a v-if="!user_logged" href="/login" class="dropdown-item"><strong>Login</strong></a>
              <!-- </li> -->

              <!-- <li v-if="user_logged" class="nav-item"> -->
              <a v-if="user_logged" href="/logout" class="dropdown-item">
                <div class="dropdown-divider"></div>
                <strong>Logout</strong>
              </a>
              <!-- </li> -->
            </div>

          </li>

至

 <li class="nav-item btn-group">
            <a class="nav-link dropdown-toggle" href="/" id="navbarDropdownMenuLink" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
              <strong>Account</strong>
            </a>
            <div class="dropdown-menu" aria-labelledby="navbarDropdownMenuLink">

              <!-- <li v-if="!user_logged" class="nav-item"> -->
              <a v-if="!user_logged" href="/signup" class="dropdown-item"><strong>Register</strong></a>
              <!-- </li> -->

              <!-- <li v-if="user_logged && user_type === 'user'" class="nav-item"> -->
              <a v-if="user_logged && user_type === 'user'" href="/profile" class="dropdown-item"><strong>Profile</strong></a>
              <a v-if="user_logged && user_type === 'user'" href="/applied" class="dropdown-item"><strong>My Jobs</strong></a>
              <a v-if="user_logged && user_type === 'user'" href="/searches" class="dropdown-item"><strong>My Searches</strong></a>

              <!-- </li> -->

              <!-- <li v-if="user_logged && user_type === 'company'" class="nav-item"> -->
              <a v-if="user_logged && user_type === 'company'" href="/dashboard" class="dropdown-item"><strong>Employer Dashboard</strong></a>
              <!-- </li> -->

              <!-- <li v-if="!user_logged" class="nav-item"> -->
              <a v-if="!user_logged" href="/login" class="dropdown-item"><strong>Login</strong></a>
              <!-- </li> -->

              <!-- <li v-if="user_logged" class="nav-item"> -->
              <a v-if="user_logged" href="/logout" class="dropdown-item">
                <div class="dropdown-divider"></div>
                <strong>Logout</strong>
              </a>
              <!-- </li> -->
            </div>

          </li>