Question

直接从Bootstrap 4页面（http://v4-alpha.getbootstrap.com/components/dropdowns/）获取代码，我将下拉列表设置/设置并正常工作，但下拉框位于页面的最左侧，而不是直接位于按钮下方。不知道为什么。有谁知道我该怎么做才能解决这个问题？ JSFiddle显示问题：https://jsfiddle.net/1m0g2fvh/

使用标准bootstrap 4的关联html：

<!DOCTYPE html>
<html lang="en">
  <head>
    <!-- Required meta tags always come first -->
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
    <meta http-equiv="x-ua-compatible" content="ie=edge">

    <!-- Bootstrap CSS -->
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.2/css/bootstrap.min.css" integrity="sha384-y3tfxAZXuh4HwSYylfB+J125MxIs6mR5FOHamPBG064zB+AFeWH94NdvaCBm8qnd" crossorigin="anonymous">
  </head>
  <body>
  <nav class="navbar navbar-dark bg-inverse">
  <a class="navbar-brand" href="#">Navbar</a>
  <ul class="nav navbar-nav">
    <li class="nav-item active">
      <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
    </li>
    <li class="nav-item">
      <button class="btn btn-secondary dropdown-toggle bg-inverse" style="border:none;" type="button" id="dropdownMenu1" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
    Dropdown
  </button>
  <div class="dropdown-menu dropdown-menu" aria-labelledby="dropdownMenu1" >
    <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>
    <li class="nav-item">
      <a class="nav-link" href="#">Pricing</a>
    </li>
    <li class="nav-item">
      <a class="nav-link" href="#">About</a>
    </li>
  </ul>
  <form class="form-inline pull-xs-right">
    <input class="form-control" type="text" placeholder="Search">
    <button class="btn btn-success-outline" type="submit">Search</button>
  </form>
</nav>

    <!-- jQuery first, then Bootstrap JS. -->
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.4/jquery.min.js"></script>
    <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.2/js/bootstrap.min.js" integrity="sha384-vZ2WRJMwsjRMW/8U7i6PWi6AlO1L79snBrmgiDpgIWJ82z8eA5lenwvxbMV1PAh7" crossorigin="anonymous"></script>
  </body>
</html>

Answer 1

将课程添加到父级dropdown

将下拉列表的触发器和下拉菜单包裹在.dropdown或其他声明position: relative;的元素中。然后，添加菜单的HTML。

<li class="nav-item dropdown">

https://jsfiddle.net/1m0g2fvh/1/

Answer 2

试试这个：

<body>
  <nav class="navbar navbar-dark bg-inverse">
  <a class="navbar-brand" href="#">Navbar</a>
  <ul class="nav navbar-nav">
    <li class="nav-item active">
      <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
    </li>
    <li class="nav-item dropdown">
      <button class="btn btn-secondary dropdown-toggle bg-inverse" style="border:none;" type="button" id="dropdownMenu1" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
    Dropdown
  </button>
  <div class="dropdown-menu dropdown-menu" aria-labelledby="dropdownMenu1" >
    <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>
    <li class="nav-item">
      <a class="nav-link" href="#">Pricing</a>
    </li>
    <li class="nav-item">
      <a class="nav-link" href="#">About</a>
    </li>
  </ul>
  <form class="form-inline pull-xs-right">
    <input class="form-control" type="text" placeholder="Search">
    <button class="btn btn-success-outline" type="submit">Search</button>
  </form>
</nav>

    <!-- jQuery first, then Bootstrap JS. -->
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.4/jquery.min.js"></script>
    <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.2/js/bootstrap.min.js" integrity="sha384-vZ2WRJMwsjRMW/8U7i6PWi6AlO1L79snBrmgiDpgIWJ82z8eA5lenwvxbMV1PAh7" crossorigin="anonymous"></script>
  </body>

DEMO HERE

Answer 3

在Bootstrap的文档中，他们说下拉菜单的对齐需要与CSS对齐。我试过这个并且它有效

.dropdown-menu{ margin-left:20%; }

Answer 4

试试这个添加这种风格

   .navbar-nav .nav-item+.nav-item{position:relative}

它正在运作

无法在Bootstrap 4.0中正确定位下拉列表

4 个答案: