Question

如何使下拉菜单向上扩展而不是向下扩展？

<!DOCTYPE html>
<html>
<head>
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css">
  <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.7/umd/popper.min.js"></script>
  <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js"></script>
</head>
<body>
<br>
<div class="container"> 
    <button type="button" class="btn btn-primary dropdown-toggle" data-toggle="dropdown">
    COLOR
    </button>
    <div class="dropdown-menu">
      <a class="dropdown-item" href="#">red</a>
      <a class="dropdown-item" href="#">yellow</a>   
  </div>
</div>
</body>
</html>

我希望下拉菜单向上而不是向下展开，但实际输出是，下拉菜单向下显示。

Answer 1

这是一个引导解决方案

<!DOCTYPE html>
<html>
<head>
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css">
  <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.7/umd/popper.min.js"></script>
  <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js"></script>
</head>
<body>
<br>
<br>
<br>
<br>


<div class="container">	
  <div class="btn-group dropup">	
  <button type="button" class="btn btn-primary dropdown-toggle" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
    COLOR
    </button>
    <div class="dropdown-menu">
      <a class="dropdown-item" href="#">red</a>
      <a class="dropdown-item" href="#">yellow</a>   
  </div>
  </div>
</div>

</body>
</html>

Answer 2

如果该按钮是您页面上唯一的按钮，并且我怀疑从您的代码中删除该下拉列表将无法工作...因此请检查下面的代码，然后尝试删除H1和p标签...

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.7/umd/popper.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js"></script>

<div class="container">
  <h1> This is demo text </h1>
  <p>There needs to be some text... else it won't open up</p>
  <div class="dropup">
    <button type="button" class="btn btn-primary dropdown-toggle" data-toggle="dropdown">
    COLOR
    </button>
    <div class="dropdown-menu">
      <a class="dropdown-item" href="#">red</a>
      <a class="dropdown-item" href="#">yellow</a>
    </div>
  </div>
</div>

我如何希望下拉菜单向上扩展而不是向下扩展

2 个答案: