如何在活动的 Bootstrap 4 下拉菜单中旋转箭头图标？

Posted 2023-03-21

【中文标题】如何在活动的 Bootstrap 4 下拉菜单中旋转箭头图标？

【英文标题】：How can I rotate the arrow icon on active Bootstrap 4 dropdown?

【发布时间】：2021-12-07 08:28:24

【问题描述】：

我有来自 Bootstrap 4 的下拉菜单。当下拉菜单打开时，我需要让箭头向上旋转。 有谁知道怎么做？

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.5.2/css/bootstrap.min.css">
<div class="dropdown">
  <button class="btn btn-secondary dropdown-toggle" type="button" id="dropdownMenuButton" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
    Dropdown button
  </button>
  <div class="dropdown-menu" aria-labelledby="dropdownMenuButton">
    <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>

【问题讨论】：

凯特，你试过什么？请参阅How to Ask。我们希望您做出努力并提出一个具体的问题。

【参考方案1】：

document.querySelectorAll(".btn").forEach(function(btn) 
  btn.parentNode.addEventListener("click", function() 
    btn.classList.toggle("rotated");
  );
);

body 
  padding: 30px; /* demo only */


.rotated::after 
  transform: rotate(180deg);

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.5.2/css/bootstrap.min.css">

<div class="dropdown">
  <button class="btn btn-secondary dropdown-toggle" type="button" id="dropdownMenuButton" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
    Dropdown button
  </button>
  <div class="dropdown-menu" aria-labelledby="dropdownMenuButton">
    <span class="dropdown-item">Dropdown content</span>
  </div>
</div>

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/bootstrap@4.6.0/dist/js/bootstrap.bundle.min.js" integrity="sha384-Piv4xVNRyMGpqkS2by6br4gNJ7DXjqk09RmUpJ8jgGtD7zP9yug3goQfGII0yAns" crossorigin="anonymous"></script>

【讨论】：

很好的解决方案，但我可能会更具体地说明您将事件处理程序和类添加到哪个类。页面上可能有很多按钮。 :)

【参考方案2】：

您可以利用Bootstrap's events for Dropdown。

body 
  padding: 30px; /* demo only */


.rotated::after 
  transform: rotate(180deg);

<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@4.6.0/dist/css/bootstrap.min.css" integrity="sha384-B0vP5xmATw1+K9KRQjQERJvTumQW0nPEzvF6L/Z6nronJ3oUOFUFpCjEUQouq2+l" crossorigin="anonymous">

<div class="dropdown" id="dropdownMenu">
  <button class="btn btn-secondary dropdown-toggle" type="button" id="dropdownMenuButton" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
    Dropdown button
  </button>
  <div class="dropdown-menu" aria-labelledby="dropdownMenuButton">
    <span class="dropdown-item">Dropdown content</span>
  </div>
</div>

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/bootstrap@4.6.0/dist/js/bootstrap.bundle.min.js" integrity="sha384-Piv4xVNRyMGpqkS2by6br4gNJ7DXjqk09RmUpJ8jgGtD7zP9yug3goQfGII0yAns" crossorigin="anonymous"></script>

<script>
$('#dropdownMenu').on('show.bs.dropdown', function() 
  $(this).find('.dropdown-toggle').addClass('rotated');
).on('hide.bs.dropdown', function() 
  $(this).find('.dropdown-toggle').removeClass('rotated');
);
</script>