Question

当窗口为全尺寸时，导航栏工作正常，但是当调整窗口大小或在移动设备上查看站点时，导航栏消失，只显示一个没有链接的小条。

<nav class="navbar fixed-top navbar-expand-lg navbar-dark bg-dark" id="navbar">
        <div class="collapse navbar-collapse">
            <ul class="navbar-nav">
                <li class="nav-item">
                    <a class="nav-link" href="#home">Home</a>
                </li>
                <li class="nav-item">
                    <a class="nav-link" href="#about">About Me</a>
                </li>
                <li class="nav-item">
                    <a class="nav-link" href="#projects">Projects</a>
                </li>
                <li class="nav-item">
                    <a class="nav-link" href="#contact">Contact Me</a>
                </li>
                <li class="nav-item">
                    <a class="nav-link" href="ResumeKJ.pdf">Resume</a>
                </li>
            </ul>
        </div>
    </nav>

Answer 1

您有两种解决方法，第一种是让navbar始终使用navbar-expand扩展来代替navbar-expand-lg：

示例1：

<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/1.14.6/umd/popper.min.js" integrity="sha384-wHAiFfRlMFy6i5SRaxvfOCifBUQy1xHdJ/yoi7FRNXMRBu5WHdZYu1hA6ZOblgut" crossorigin="anonymous"></script>
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.2.1/css/bootstrap.min.css" integrity="sha384-GJzZqFGwb1QTTN6wy59ffF1BuGJpLSa9DkKMp0DgiMDm4iYMj70gZWKYbI706tWS" crossorigin="anonymous">
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.2.1/js/bootstrap.min.js" integrity="sha384-B0UglyR+jN6CkvvICOB2joaf5I4l3gm9GU6Hc1og6Ls7i6U/mkkaduKaBhlAXv9k" crossorigin="anonymous"></script>

<nav class="navbar fixed-top navbar-expand navbar-dark bg-dark" id="navbar">
  <div class="collapse navbar-collapse">
    <ul class="navbar-nav">
      <li class="nav-item">
        <a class="nav-link" href="#home">Home</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#about">About Me</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#projects">Projects</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#contact">Contact Me</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="ResumeKJ.pdf">Resume</a>
      </li>
    </ul>
  </div>
</nav>

第二种方法是添加支持导航栏折叠模式（Read more here）的代码，但是您只需要添加用于切换折叠导航栏的按钮即可：

<button class="navbar-toggler" type="button" data-toggle="collapse" data-target=".navbar-collapse" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
  <span class="navbar-toggler-icon"></span>
</button>

示例2：

<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/1.14.6/umd/popper.min.js" integrity="sha384-wHAiFfRlMFy6i5SRaxvfOCifBUQy1xHdJ/yoi7FRNXMRBu5WHdZYu1hA6ZOblgut" crossorigin="anonymous"></script>
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.2.1/css/bootstrap.min.css" integrity="sha384-GJzZqFGwb1QTTN6wy59ffF1BuGJpLSa9DkKMp0DgiMDm4iYMj70gZWKYbI706tWS" crossorigin="anonymous">
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.2.1/js/bootstrap.min.js" integrity="sha384-B0UglyR+jN6CkvvICOB2joaf5I4l3gm9GU6Hc1og6Ls7i6U/mkkaduKaBhlAXv9k" crossorigin="anonymous"></script>

<nav class="navbar fixed-top navbar-expand-lg navbar-dark bg-dark" id="navbar">
  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target=".navbar-collapse" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>
  <div class="collapse navbar-collapse">
    <ul class="navbar-nav">
      <li class="nav-item">
        <a class="nav-link" href="#home">Home</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#about">About Me</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#projects">Projects</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#contact">Contact Me</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="ResumeKJ.pdf">Resume</a>
      </li>
    </ul>
  </div>
</nav>

Answer 2

您同时缺少navbar-brand（这是可选的但显示在右侧）和navbar-toggle这两者（显示用于扩展导航栏的按钮）；还记得在折叠部分添加id以供参考

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<link href="https://stackpath.bootstrapcdn.com/bootstrap/4.2.1/css/bootstrap.min.css" rel="stylesheet" />
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.2.1/js/bootstrap.min.js"></script>

<nav class="navbar fixed-top navbar-expand-lg navbar-dark bg-dark" id="navbar">
  <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 class="nav-link" href="#home">Home</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#about">About Me</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#projects">Projects</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#contact">Contact Me</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="ResumeKJ.pdf">Resume</a>
      </li>
    </ul>
  </div>
</nav>

Bootstrap导航栏未出现在移动设备上

2 个答案: