javascript - 使用纯 JS 和 CSS 动画导航栏折叠

Question

我想从我的 Bootstrap 模板中删除 jquery，因为我不使用 JS 组件。所以我删除了它并在纯 JS 中为 navbar-toggle 添加了后备代码(检查附加的 JSFiddle)。 现在我想为导航栏切换设置动画(使用 CSS 或纯 JS)。

我尝试了最大高度的过渡属性。但我不知道最终高度，因为里面有一个下拉菜单。所以如果我使用一些大的高度，那么崩溃就会延迟。

我使用 getbootstrap 中的示例模板创建了一个 JSFiddle:https://jsfiddle.net/c5f82stw/

// Navbar and dropdowns
var toggle = document.getElementsByClassName('navbar-toggle')[0],
  collapse = document.getElementsByClassName('navbar-collapse')[0],
  dropdowns = document.getElementsByClassName('dropdown');;

// Toggle if navbar menu is open or closed
function toggleMenu() {
  collapse.classList.toggle('collapse');
  collapse.classList.toggle('in');
}

// Close all dropdown menus
function closeMenus() {
  for (var j = 0; j < dropdowns.length; j++) {
    dropdowns[j].getElementsByClassName('dropdown-toggle')[0].classList.remove('dropdown-open');
    dropdowns[j].classList.remove('open');
  }
}

// Add click handling to dropdowns
for (var i = 0; i < dropdowns.length; i++) {
  dropdowns[i].addEventListener('click', function() {
    if (document.body.clientWidth < 768) {
      var open = this.classList.contains('open');
      closeMenus();
      if (!open) {
        this.getElementsByClassName('dropdown-toggle')[0].classList.toggle('dropdown-open');
        this.classList.toggle('open');
      }
    }
  });
}

// Close dropdowns when screen becomes big enough to switch to open by hover
function closeMenusOnResize() {
  if (document.body.clientWidth >= 768) {
    closeMenus();
    collapse.classList.add('collapse');
    collapse.classList.remove('in');
  }
}

// Event listeners
window.addEventListener('resize', closeMenusOnResize, false);
toggle.addEventListener('click', toggleMenu, false);

<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet" />
<div class="container">

  <!-- Static navbar -->
  <nav class="navbar navbar-default">
    <div class="container-fluid">
      <div class="navbar-header">
        <button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#navbar" aria-expanded="false" aria-controls="navbar">
              <span class="sr-only">Toggle navigation</span>
              <span class="icon-bar"></span>
              <span class="icon-bar"></span>
              <span class="icon-bar"></span>
            </button>
        <a class="navbar-brand" href="#">Project name</a>
      </div>
      <div id="navbar" class="navbar-collapse collapse">
        <ul class="nav navbar-nav">
          <li class="active"><a href="#">Home</a></li>
          <li><a href="#">About</a></li>
          <li><a href="#">Contact</a></li>
          <li class="dropdown">
            <a href="#" class="dropdown-toggle" data-toggle="dropdown" role="button" aria-haspopup="true" aria-expanded="false">Dropdown <span class="caret"></span></a>
            <ul class="dropdown-menu">
              <li><a href="#">Action</a></li>
              <li><a href="#">Another action</a></li>
              <li><a href="#">Something else here</a></li>
              <li role="separator" class="divider"></li>
              <li class="dropdown-header">Nav header</li>
              <li><a href="#">Separated link</a></li>
              <li><a href="#">One more separated link</a></li>
            </ul>
          </li>
        </ul>
        <ul class="nav navbar-nav navbar-right">
          <li class="active"><a href="./">Default <span class="sr-only">(current)</span></a></li>
          <li><a href="../navbar-static-top/">Static top</a></li>
          <li><a href="../navbar-fixed-top/">Fixed top</a></li>
        </ul>
      </div>
      <!--/.nav-collapse -->
    </div>
    <!--/.container-fluid -->
  </nav>

  <!-- Main component for a primary marketing message or call to action -->
  <div class="jumbotron">
    <h1>Navbar example</h1>
    <p>This example is a quick exercise to illustrate how the default, static navbar and fixed to top navbar work. It includes the responsive CSS and HTML, so it also adapts to your viewport and device.</p>
    <p>
      <a class="btn btn-lg btn-primary" href="../../components/#navbar" role="button">View navbar docs &raquo;</a>
    </p>
  </div>

</div>
<!-- /container -->

Answer 1

我知道这不是我想要的。我在找 JS 的东西。

根据您的需要微调最大高度。下拉菜单需要额外的高度才能工作。请记住这一点。

.navbar-collapse.in 

    max-height: 65em;

JSFiddle:https://jsfiddle.net/g3hwf2yo/2/

.navbar-collapse{
    max-height: 0px;
transition: max-height 0.5s cubic-bezier(0, 1, 0, 1);
background: #d5d5d5;
overflow: hidden;
display: block;
    margin-top: 0.5em;
}
.navbar-collapse.in {

    max-height: 65em;
    transition: max-height 1s ease-in-out;
}

这使用三次贝塞尔曲线来微调动画。

    <link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet" />
<div class="container">

  <!-- Static navbar -->
  <nav class="navbar navbar-default">
    <div class="container-fluid">
      <div class="navbar-header">
        <button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#navbar" aria-expanded="false" aria-controls="navbar">
              <span class="sr-only">Toggle navigation</span>
              <span class="icon-bar"></span>
              <span class="icon-bar"></span>
              <span class="icon-bar"></span>
            </button>
        <a class="navbar-brand" href="#">Project name</a>
      </div>
      <div id="navbar" class="navbar-collapse collapse">
        <ul class="nav navbar-nav">
          <li class="active"><a href="#">Home</a></li>
          <li><a href="#">About</a></li>
          <li><a href="#">Contact</a></li>
          <li class="dropdown">
            <a href="#" class="dropdown-toggle" data-toggle="dropdown" role="button" aria-haspopup="true" aria-expanded="false">Dropdown <span class="caret"></span></a>
            <ul class="dropdown-menu">
              <li><a href="#">Action</a></li>
              <li><a href="#">Another action</a></li>
              <li><a href="#">Something else here</a></li>
              <li role="separator" class="divider"></li>
              <li class="dropdown-header">Nav header</li>
              <li><a href="#">Separated link</a></li>
              <li><a href="#">One more separated link</a></li>
            </ul>
          </li>
        </ul>
        <ul class="nav navbar-nav navbar-right">
          <li class="active"><a href="./">Default <span class="sr-only">(current)</span></a></li>
          <li><a href="../navbar-static-top/">Static top</a></li>
          <li><a href="../navbar-fixed-top/">Fixed top</a></li>
        </ul>
      </div>
      <!--/.nav-collapse -->
    </div>
    <!--/.container-fluid -->
  </nav>

  <!-- Main component for a primary marketing message or call to action -->
  <div class="jumbotron">
    <h1>Navbar example</h1>
    <p>This example is a quick exercise to illustrate how the default, static navbar and fixed to top navbar work. It includes the responsive CSS and HTML, so it also adapts to your viewport and device.</p>
    <p>
      <a class="btn btn-lg btn-primary" href="../../components/#navbar" role="button">View navbar docs &raquo;</a>
    </p>
  </div>

</div>
<!-- /container -->

最后是 JS

// Navbar and dropdowns
var toggle = document.getElementsByClassName('navbar-toggle')[0],
  collapse = document.getElementsByClassName('navbar-collapse')[0],
  dropdowns = document.getElementsByClassName('dropdown');;

// Toggle if navbar menu is open or closed
function toggleMenu() {
  collapse.classList.toggle('collapse');
  collapse.classList.toggle('in');
}

// Close all dropdown menus
function closeMenus() {
  for (var j = 0; j < dropdowns.length; j++) {
    dropdowns[j].getElementsByClassName('dropdown-toggle')[0].classList.remove('dropdown-open');
    dropdowns[j].classList.remove('open');
  }
}

// Add click handling to dropdowns
for (var i = 0; i < dropdowns.length; i++) {
  dropdowns[i].addEventListener('click', function() {
    if (document.body.clientWidth < 768) {
      var open = this.classList.contains('open');
      closeMenus();
      if (!open) {
        this.getElementsByClassName('dropdown-toggle')[0].classList.toggle('dropdown-open');
        this.classList.toggle('open');
      }
    }
  });
}

// Close dropdowns when screen becomes big enough to switch to open by hover
function closeMenusOnResize() {
  if (document.body.clientWidth >= 768) {
    closeMenus();
    collapse.classList.add('collapse');
    collapse.classList.remove('in');
  }
}

// Event listeners
window.addEventListener('resize', closeMenusOnResize, false);
toggle.addEventListener('click', toggleMenu, false);

祝你有美好的一天!