我无法使引导程序切换按钮在浏览器上工作，如何识别问题？
PS，我已经在我的head标签中添加了Bootstrap CDN，并在正文中添加了jQuery和JavaScript。
<nav class="navbar navbar-dark bg-dark navbar-expand-md">
<a href="#" class="navbar-brand">NAVBAR</a>
<button class="navbar-toggler" type="button" data-toggle="collapse" data-
target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false"
aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="#navbarSupportedContent">
<ul class="navbar-nav">
<li class="nav-item">
<a href="#" class="nav-link">HOME</a>
</li>
<li class="nav-item">
<a href="#" class="nav-link">ABOUT</a>
</li>
<li class="nav-item">
<a href="#" class="nav-link">TICKETS</a>
</li>
</ul>
</div>
</nav>
尝试一下
<!DOCTYPE html>
<html lang="en">
<head>
<title>Bootstrap Example</title>
<meta charset="utf-8">
<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/3.4.1/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>
<nav class="navbar navbar-dark bg-dark">
<a class="navbar-brand" href="#">Navbar</a>
<button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navbarSupportedContent">
<ul class="navbar-nav">
<li class="nav-item">
<a href="#" class="nav-link">HOME</a>
</li>
<li class="nav-item">
<a href="#" class="nav-link">ABOUT</a>
</li>
<li class="nav-item">
<a href="#" class="nav-link">TICKETS</a>
</li>
</ul>
</div>
</nav>
</body>
</html>id属性不应以#开头。它应该只是：id="navbarSupportedContent"
<nav class="navbar navbar-dark bg-dark navbar-expand-md">
<a href="#" class="navbar-brand">NAVBAR</a>
<button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navbarSupportedContent">
<ul class="navbar-nav">
<li class="nav-item">
<a href="#" class="nav-link">HOME</a>
</li>
<li class="nav-item">
<a href="#" class="nav-link">ABOUT</a>
</li>
<li class="nav-item">
<a href="#" class="nav-link">TICKETS</a>
</li>
</ul>
</div>
</nav>
下拉菜单基于第三方库Popper.js构建，该库提供动态定位和视口检测。确保在Bootstrap的JavaScript之前包含popper.min.js或使用包含Popper.js的bootstrap.bundle.min.js / bootstrap.bundle.js。
这是在Bootstrap文档中编写的）））