<link rel="stylesheet" href="../Boot strap/bootstrap-4.1.3-dist/css/bootstrap.min.css">
<script src="../Boot strap/jquery-3.4.1.js"></script>
<script src="../Boot strap/bootstrap-4.1.3-dist/js/bootstrap.bundle.min.js"></script>
<script src="../Boot strap/bootstrap-4.1.3-dist/js/bootstrap.min.js"></script>
如下拉菜单:
<div class="dropdown">
<button type="button" class="btn btn-primary dropdown-toggle" data-toggle="dropdown">
Dropdown button
</button>
<div class="dropdown-menu"> <a class="dropdown-item" href="#">Link 1</a>
<a class="dropdown-item" href="#">Link 2</a>
<a class="dropdown-item" href="#">Link 3</a>
</div>
</div>
2(Bootstrap4 插件的引用)
原文：https://www.cnblogs.com/m9m941102/p/11712181.html
