Question

我有一个Bootstrap / Popper.js下拉菜单，当页面高度小于下拉菜单时（即，当高度降低到该菜单不再适合的高度时），该菜单会被推到页面顶部在页面上。）

而不是像现在那样将整个下拉菜单上推至页面顶部，我希望它保持原样。我该怎么办？

例如：

当页面高度允许下拉菜单适合时

如果页面高度太小而下拉菜单无法容纳

<!doctype html>
<html>

<head>
  <meta charset="utf-8">
  <title></title>
  <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.2.1/css/bootstrap.min.css" integrity="sha384-GJzZqFGwb1QTTN6wy59ffF1BuGJpLSa9DkKMp0DgiMDm4iYMj70gZWKYbI706tWS" crossorigin="anonymous">
  <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
</head>

<body>
  <div class="dropdown custom-drop hide">
    <a class="btn float-right btn-secondary btn-lg dropdown-toggle" href="#" role="button" id="dropdownMenuLink" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
    Menu
  </a>
    <div class="dropdown-menu" aria-labelledby="dropdownMenuLink">
      <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>
  </div>
  <style>
    .dropdown {
      position: absolute;
      z-index: 99;
      width: calc(100% - 320px);
      top: 100px;
      right: 0px;
    }
    
    .dropdown-toggle {
      margin-right: 50px;
    }
    
    .dropdown-menu {
      position: absolute;
      text-align: center;
      z-index: 999;
      width: calc(100% + 320px);
    }
    
    .dropdown-item {
      padding: 0.75rem 1.5rem;
      width: 100%;
    }
  </style>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.11.0/umd/popper.min.js" integrity="sha384-b/U6ypiBEHpOf/4+1nzFpr53nxSS+GLCkfwBdFNTxtclqqenISfwAzpKaMNFNmj4" crossorigin="anonymous"></script>
  <script src="https://stackpath.bootstrapcdn.com/bootstrap/4.2.1/js/bootstrap.min.js" integrity="sha384-B0UglyR+jN6CkvvICOB2joaf5I4l3gm9GU6Hc1og6Ls7i6U/mkkaduKaBhlAXv9k" crossorigin="anonymous"></script>
</body>

</html>

如何停止Bootstrap / Popper.js下拉列表在小页面高度上被推到页面顶部？

0 个答案: