切换菜单立即消失答案

【问题标题】：Toggle menu disappears instantly切换菜单立即消失
【发布时间】：2019-03-22 18:11:23
【问题描述】：

通过单击切换按钮，我只能看到菜单（我已在切换按钮上设置）仅四分之一秒，然后消失。我是新手。我可能犯了一些非常明显的错误。任何帮助表示赞赏。

<html>
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width,initial-scale=1.0">
    <link rel="stylesheet" type="text/css" href="css/bootstrap.min.css">
    <link rel="stylesheet" type="text/css" href="css/style.css">    
    <script src="https://code.jquery.com/jquery-2.1.3.min.js"></script>
    <script src="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.1/js/bootstrap.min.js"></script>
    <script src="js/jquery.min.js"></script>
    <script src="js/bootstrap.min.js"></script>
    <title></title>
</head>
<body>
    <div class="container ">
        <nav class="navbar navbar-expand-sm  navbar-dark bg-dark">      
            <a href="#" class="navbar-brand"><img src="logo.png">The building co.</a>
            <button type="button" class="navbar-toggler" data-toggle="collapse" data-target="#myMenu">
                <span class="navbar-toggler-icon"></span>
            </button>
            <div class="collapse navbar-collapse" id="myMenu">
                <ul class="navbar-nav">
                    <li class="nav-item" > <a href="#" class="navbar-link">Home </a> </li>
                    <li class="nav-item" > <a href="#" class="navbar-link">contact us </a> </li>
                    <li class="nav-item" > <a href="#" class="navbar-link">policy </a> </li>
                    <li class="nav-item" > <a href="#" class="navbar-link">terms </a> </li>
                    <li class="nav-item" > <a href="#" class="navbar-link">About us </a> </li>          
                </ul>
            </div>
        </nav>  
    </div>
</body>
</html>

【问题讨论】：

您是否对 CSS 进行了任何更改？
还没有。我只是使用引导类而不做任何更改。

标签： javascript html css bootstrap-4

【解决方案1】：

首先，根据引导程序documentation，您拥有确切的入门模板。

<!doctype html>
<html lang="en">
  <head>
    <!-- Required meta tags -->
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">

    <!-- Bootstrap CSS -->
    <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css" integrity="sha384-ggOyR0iXCbMQv3Xipma34MD+dH/1fQ784/j6cY/iJTQUOhcWr7x9JvoRxT2MZw1T" crossorigin="anonymous">

    <title>Hello, world!</title>
  </head>
  <body>
    <h1>Hello, world!</h1>

    <!-- Optional JavaScript -->
    <!-- jQuery first, then Popper.js, then Bootstrap JS -->
    <script src="https://code.jquery.com/jquery-3.3.1.slim.min.js" integrity="sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" crossorigin="anonymous"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.7/umd/popper.min.js" integrity="sha384-UO2eT0CpHqdSJQ6hJty5KVphtPhzWj9WO1clHTMGa3JDZwrnQq4sF86dIHNDz0W1" crossorigin="anonymous"></script>
    <script src="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js" integrity="sha384-JjSmVgyd0p3pXB1rRibZUAYoIIy6OrQ6VrjIEaFf/nJGzIxFDsf4x0xIM+B07jRM" crossorigin="anonymous"></script>
  </body>
</html>

然后根据引导documentation sample放引导导航栏组件链接。

【讨论】：

谢谢先生，它有效:)。但我无法知道实际错误在哪里。
@Danishmahmood 在处理 javascript 时，将脚本放在页面底部很重要，因为它们在加载和执行时会阻止渲染。你可以阅读这些guidelines。

【解决方案2】：

您丢失或使用了不正确的bootstrap.min.css 路径。更正后，您的代码就可以工作了：

<html>

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width,initial-scale=1.0">
  <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.4.0/css/bootstrap.min.css">
  <link rel="stylesheet" type="text/css" href="css/style.css">
  <script src="https://code.jquery.com/jquery-2.1.3.min.js"></script>
  <script src="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.1/js/bootstrap.min.js"></script>
  <script src="js/jquery.min.js"></script>
  <script src="js/bootstrap.min.js"></script>
  <title></title>
</head>

<body>
  <div class="container ">
    <nav class="navbar navbar-expand-sm  navbar-dark bg-dark">
      <a href="#" class="navbar-brand"><img src="logo.png">The building co.</a>
      <button type="button" class="navbar-toggler" data-toggle="collapse" data-target="#myMenu">
            <span class="navbar-toggler-icon"></span>
        </button>
      <div class="collapse navbar-collapse" id="myMenu">
        <ul class="navbar-nav">
          <li class="nav-item"> <a href="#" class="navbar-link">Home </a> </li>
          <li class="nav-item"> <a href="#" class="navbar-link">contact us </a> </li>
          <li class="nav-item"> <a href="#" class="navbar-link">policy </a> </li>
          <li class="nav-item"> <a href="#" class="navbar-link">terms </a> </li>
          <li class="nav-item"> <a href="#" class="navbar-link">About us </a> </li>
        </ul>
      </div>
    </nav>
  </div>
</body>

</html>

【讨论】：