Bootstrap 4 导航栏切换不工作（下面粘贴的代码）

Question

我无法让 bootstrap 切换按钮在浏览器上工作，如何确定问题所在？

PS 我已经在 head 标签中添加了 Bootstrap CDN，并在 body 标签中添加了 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>

Answer 1

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>

https://www.codeply.com/p/xYH3DTrwlt

Answer 2

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。请务必在 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

popper.js.org

这写在 Bootstrap 文档中)))

Answer 3

试试这个

删除 .navbar-expand-md class 以始终隐藏导航栏链接并显示切换按钮。

<!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>

Answer 4

data-target="#navbarSupportedContent"

# 符号代表 id。

问题在这里：

id="#navbarSupportedContent"

这应该是

id="navbarSupportedContent"

Bootstrap 4 导航栏切换不工作（下面粘贴的代码）

Bootstrap 4 Navbar Toggle not working (code pasted below)

html

css

nav

bootstrap-4