我想为新的 Bootsrap 5 使用多级下拉菜单。我尝试了 4 的旧代码，但没有任何效果。有人有 Bootstrap 5 的工作代码吗？
您可以使用普通的引导组件来实现它，而不需要任何额外的 JavaScript 代码： 这个想法是将 Dropdowns 组件 与嵌套的 Dropend 或 Dropstart 组件一起使用，并在父 Dropdown 组件上使用选项 data-bs-auto-close="outside" 。 检查下面的简单示例：
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Bootstrap demo</title>
<link href="https://cdn.jsdelivr.net/npm/[email protected]/dist/css/bootstrap.min.css" rel="stylesheet"
integrity="sha384-Zenh87qX5JnK2Jl0vWa8Ck2rdkQ2Bzep5IDxbcnCeuOxjzrPF/et3URy9Bv1WTRi" crossorigin="anonymous">
</head>
<body>
<div class="dropdown">
<button
class="btn btn-secondary dropdown-toggle bg-transparent text-dark btn-sm ms-3"
type="button"
id="MyAccountDDM"
data-bs-toggle="dropdown"
data-bs-auto-close="outside"
aria-expanded="false">
AAA
</button>
<ul class="dropdown-menu" aria-labelledby="MyAccountDDM" id="AppDropDownId">
<li><a>BBB</a></li>
<li>
<div class="btn-group dropend">
<a type="button" class="dropdown-item dropdown-toggle p-0" data-bs-toggle="dropdown"
aria-expanded="false">
CCC
</a>
<ul class="dropdown-menu">
<li><a class="dropdown-item" href="#">DDD</a></li>
<li><a class="dropdown-item" href="#">EEE</a></li>
</ul>
</div>
</li>
<li><hr class="dropdown-divider"/></li>
<li><a>FFF</a></li>
</ul>
</div>
<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/js/bootstrap.bundle.min.js"
integrity="sha384-OERcA2EqjJCMA+/3y+gxIOqMEjwtxJY7qPCqsdltbNJuaOe923+mo//f6V8Qbsw3"
crossorigin="anonymous"></script>
</body>
</html>多级菜单项，只需少量 CSS 自定义
.dropdown:hover >.dropdown-menu{
display: block !important;
}
.dropdown-submenu:hover > .dropdown-menu{
display: block !important;
left: 100%;
margin-top: -37px;
}
.dropdown-item{
font-size: small; /* 13px */
}
.dropdown-toggle::after{
font-size: var(--font-md);
margin-bottom: -2px;
}
.dropdown-menu li a.active{
color:#fff;
}
.custom-toggle-arrow{
font-size: 18px;
margin-top: 1px;
line-height: 12px;
}<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Bootstrap demo</title>
<link href="https://cdn.jsdelivr.net/npm/[email protected]/dist/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-gH2yIJqKdNHPEq0n4Mqa/HGKIhSkIHeL5AyhkYV8i59U5AR6csBvApHHNl/vI1Bx" crossorigin="anonymous">
</head>
<body>
<nav class="nav justify-content-center" aria-label="Secondary navigation">
<li class="nav-item"><a class="nav-link" href="#">Single Item</a></li>
<li class="nav-item dropdown">
<a class="nav-link dropdown-toggle" href="#" role="button" data-bs-toggle="dropdown" aria-expanded="false">
Multi-level Item
</a>
<ul class="dropdown-menu">
<li><a class="dropdown-item" href="#"> Menu Item 1</a></li>
<li><a class="dropdown-item" href="#"> Menu Item 2</a></li>
<li class="dropdown-submenu">
<a class="dropdown-item" href="#"> Second Level <span
class="float-end custom-toggle-arrow">»</span></a>
<ul class="dropdown-menu">
<li><a class="dropdown-item" href="#">Second Level Item 1</a></li>
<li><a class="dropdown-item" href="#">Second Level Item 2</a></li>
<li class="dropdown-submenu">
<a class="dropdown-item" href="#"> Third Level <span
class="float-end custom-toggle-arrow">»</span></a>
<ul class="dropdown-menu">
<li><a class="dropdown-item" href="#">Third Level Item 1</a></li>
<li><a class="dropdown-item" href="#">Third Level Item 2</a></li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
</nav>
<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/js/bootstrap.bundle.min.js" integrity="sha384-A3rJD856KowSb7dwlZdYEkO39Gagi7vIsF0jrRAoQmDKKtQBHUuLZ9AsSv4jD4Xa" crossorigin="anonymous"></script>
</body>
</html>参考：链接
感谢您提供这个解决方案，非常有帮助。 :)