Bootstrap 4：在Navbar折叠时显示活动导航项

时间：2018-03-24 12:02:59

标签： javascript html css twitter-bootstrap bootstrap-4

我尝试使用在特定视口宽度处折叠的引导程序创建导航栏。现在，我想看到的是，如果导航条折叠，<html lang="en"><head> <meta charset="utf-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge"> <meta name="viewport" content="width=device-width, initial-scale=1"> <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous"> </head> <body> <nav class="navbar navbar-inverse navbar-fixed-top"> <div class="container"> <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="collapse navbar-collapse"> <ul class="nav navbar-nav"> <li class="active"><a href="#">Home</a></li> <li><a href="#about">About</a></li> <li><a href="#contact">Contact</a></li> </ul> </div><!--/.nav-collapse --> </div> </nav> <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script> <script>window.jQuery || document.write('<script src="../../assets/js/vendor/jquery.min.js"><\/script>')</script> <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js" integrity="sha384-Tc5IQib027qvyjSMfHjOMaLkfuWVxZxUPnCJA7l2mCWNIpG9mGCD8wGNIcPD7Txa" crossorigin="anonymous"></script> </body></html>消失，当前有效的导航项目（例如＆＃39; Home＆＃39;，＆＃39; About＆＃39;等等将在左侧可见，从而使访问者能够看到他们在哪个页面。

我是一个完全自举的菜鸟，我有点希望在导航栏折叠/展开时看到要添加的css类，但它不会那样工作。

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3 个答案:

答案 0 :(得分：1)

不完全是“开箱即用”，但有一点CSS可以与Bootstrap 4一起使用（没有jquery或者重复标记）......

https://stackoverflow.com/a/19677968/9544599

这会覆盖导航栏折叠行为以使用visibility而不是display。这样我们就可以控制active导航项的显示。

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous">
<script src="https://code.jquery.com/jquery-3.2.1.slim.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js" ></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js"></script>
    
<style>
.navbar .collapse {
    visibility: hidden;
    display: block;
}

.navbar .collapse.show {
    visibility: visible;
}

@media (max-width: 767px) {
    .navbar-nav .nav-link.active {
        visibility: visible;
    }
    
    .collapsing {
        transition: all 0.35s ease;
        height: 40px !important;
    }
    
    .collapse:not(.show) .navbar-nav .nav-item:not(.active) {
        display: none;
    }
}

@media (min-width: 768px) {
    .navbar .collapse .navbar-nav .nav-item {
        visibility: visible;
    }
}
</style>
<body>
<nav class="navbar navbar-expand-md fixed-top navbar-dark bg-dark">
    <div class="container">
        <div class="collapse" id="navbar1">
            <div class="navbar-nav flex-md-row">
                <a class="nav-item navbar-brand" href="#">Project name</a>
                <a class="nav-item nav-link" href="#">Home</a>
                <a class="nav-item nav-link" href="#">About</a>
                <a class="nav-item nav-link active" href="#">Contact</a>
            </div>
        </div>
        <button class="navbar-toggler align-self-start" type="button" data-toggle="collapse" data-target="#navbar1">
            <span class="navbar-toggler-icon"></span>
        </button>
    </div>
</nav>
</body>

请注意，@ media查询伴随着navbar-expand-md断点768px。如果需要，您可以更改它以使用不同的断点。

navbar-expand-sm - 576px
navbar-expand-lg - 992px
navbar-expand-xl - 1200px

还有另一个解决方案使用重复的navbar-nav链接，但这需要额外的标记，我认为上面的CSS唯一解决方案更清晰。

答案 1 :(得分：0)

试试这个解决方案。虽然需要先进行此操作才能使可用的导航菜单链接可以点击。

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<html lang="en">
  <head>
        <meta charset="utf-8">
        <meta http-equiv="X-UA-Compatible" content="IE=edge">
        <meta name="viewport" content="width=device-width, initial-scale=1">
        <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">
  </head>
  <body>
        <nav class="navbar navbar-inverse navbar-fixed-top">
          <div class="container">
            <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="collapse navbar-collapse">
              <ul class="nav navbar-nav">
                <li class="active"><a href="#">Home</a></li>
                <li><a href="#about">About</a></li>
                <li><a href="#contact">Contact</a></li>
              </ul>
            </div><!--/.nav-collapse -->
          </div>
        </nav>

        <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>
        <script>window.jQuery || document.write('<script src="../../assets/js/vendor/jquery.min.js"><\/script>')</script>
        <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js" integrity="sha384-Tc5IQib027qvyjSMfHjOMaLkfuWVxZxUPnCJA7l2mCWNIpG9mGCD8wGNIcPD7Txa" crossorigin="anonymous"></script>
      <script>
          $ = window.jQuery
          $(document).ready(function(){
            $('.navbar-brand').attr('data-brand',$('.navbar-brand').text())
               var txtMenu = $('#navbar ul.navbar-nav .active').text();
               $('.navbar-brand').text(txtMenu)
               $('nav.navbar').on('hide.bs.collapse', function(){ 
               var txtM = $('#navbar ul.navbar-nav .active').text();
               $('.navbar-brand').text(txtM)
            })
            $('nav.navbar').on('show.bs.collapse', function(){ 
               var txtB = $('.navbar-brand').attr('data-brand');
               $('.navbar-brand').text(txtB)
            })
          })
      </script>
</body></html>
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答案 2 :(得分：0)

不能直接在bootstrap中使用，但您可以在此处编写一个小的Javascript代码：

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function displayActiveMenu() {
  if ($(window).width() >= 768) {
    // do nothing if we are not collapsed
    return;
  }

  var element = $('li.active', '#navbar').clone();
  $('#active-navbar').html(element);
}

displayActiveMenu(); // for the first time
$(window).on('resize', displayActiveMenu);
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@media (max-width: 767px) {
  #active-navbar {
    float: right;
    margin: 0;
  }
  #active-navbar>li>a {
     padding-top: 15px;
     padding-bottom: 15px;
  }
}
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<html lang="en">

<head>
  <meta charset="utf-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">
</head>

<body>
  <nav class="navbar navbar-inverse navbar-fixed-top">
    <div class="container">
      <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>

          <!-- this is the new element -->
          <ul class="nav navbar-nav visible-xs" id="active-navbar">
          </ul>

          <a class="navbar-brand" href="#">Project name</a>
      </div>

      <div id="navbar" class="collapse navbar-collapse">
        <ul class="nav navbar-nav">
          <li class="active"><a href="#">Home</a></li>
          <li><a href="#about">About</a></li>
          <li><a href="#contact">Contact</a></li>
        </ul>
      </div>
      <!--/.nav-collapse -->
    </div>
  </nav>

  <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>
  <script>
    window.jQuery || document.write('<script src="../../assets/js/vendor/jquery.min.js"><\/script>')
  </script>
  <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js" integrity="sha384-Tc5IQib027qvyjSMfHjOMaLkfuWVxZxUPnCJA7l2mCWNIpG9mGCD8wGNIcPD7Txa" crossorigin="anonymous"></script>

</body>

</html>
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