Bootstrap4 导航学习笔记

导航栏的基本结构

Bootstrap4 的导航栏由以下几部分组成：

htmlCopy Code
<nav class="navbar navbar-expand-lg navbar-light bg-light">
  <a class="navbar-brand" href="#">品牌名称</a>
  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarNav" aria-controls="navbarNav" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>
  <div class="collapse navbar-collapse" id="navbarNav">
    <ul class="navbar-nav">
      <li class="nav-item active">
        <a class="nav-link" href="#">首页<span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">关于我们</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">服务内容</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">联系我们</a>
      </li>
    </ul>
  </div>
</nav>

其中，navbar 是整个导航栏的容器，navbar-brand 是品牌名称（通常会放在最左边），navbar-toggler 是用于响应式导航栏的按钮，navbar-collapse 是响应式导航栏的折叠容器，navbar-nav 是导航栏的链接容器，nav-item 是单个链接的容器，nav-link 是链接本身。

常见的导航栏样式

Bootstrap4 中预设了几种常见的导航栏样式。

顶部固定导航栏

htmlCopy Code
<nav class="navbar navbar-expand-lg navbar-light bg-light fixed-top">
  <a class="navbar-brand" href="#">品牌名称</a>
  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarNav" aria-controls="navbarNav" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>
  <div class="collapse navbar-collapse" id="navbarNav">
    <ul class="navbar-nav">
      <li class="nav-item active">
        <a class="nav-link" href="#">首页<span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">关于我们</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">服务内容</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">联系我们</a>
      </li>
    </ul>
  </div>
</nav>

底部固定导航栏

htmlCopy Code
<nav class="navbar navbar-expand-lg navbar-light bg-light fixed-bottom">
  <a class="navbar-brand" href="#">品牌名称</a>
  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarNav" aria-controls="navbarNav" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>
  <div class="collapse navbar-collapse" id="navbarNav">
    <ul class="navbar-nav">
      <li class="nav-item active">
        <a class="nav-link" href="#">首页<span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">关于我们</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">服务内容</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">联系我们</a>
      </li>
    </ul>
  </div>
</nav>

固定在顶部，滚动时隐藏

htmlCopy Code
<nav class="navbar navbar-expand-lg navbar-light bg-light sticky-top">
  <a class="navbar-brand" href="#">品牌名称</a>
  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarNav" aria-controls="navbarNav" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>
  <div class="collapse navbar-collapse" id="navbarNav">
    <ul class="navbar-nav">
      <li class="nav-item active">
        <a class="nav-link" href="#">首页<span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">关于我们</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">服务内容</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">联系我们</a>
      </li>
    </ul>
  </div>
</nav>

小结

Bootstrap4 中的导航栏是一个非常实用的组件，可以快速构建出优美、响应式的导航栏。上述示例仅仅是其中的冰山一角，希望本篇学习笔记能够对读者有所帮助。