Bootstrap 4：仅当nav-tab处于活动状态时才显示元素

I'm making nav-tabs that need to have an element shown only on active one. In my case, it's the white arrow pointing down to the content. How can I make it vanish when you click on another tab? Or, how can i move it to that tab so it points to its content instead?

我正在制作导航标签,需要在活动标签上显示一个元素。就我而言,它是指向内容的白色箭头。当您点击另一个标签时,如何让它消失?或者,我如何将其移动到该选项卡,以便指向其内容?

Here's the outline of my code:

这是我的代码的大纲:

.arrow-down {
    position: absolute;
    width: 0; 
    height: 0; 
    border-left: 15px solid transparent;
    border-right: 15px solid transparent;
    border-top: 15px solid white;
  margin-left: 20px;
}
.nav-tabs {
    background-color: black;
}
.tab-content {
  background-color: #ccc
}

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.6/css/bootstrap.min.css" integrity="sha384-rwoIResjU2yc3z8GV/NPeZWAv56rSmLldC3R/AZzGRnGxQQKnKkoFVhFQhNUwEyJ" crossorigin="anonymous">
<script src="https://code.jquery.com/jquery-3.1.1.slim.min.js" integrity="sha384-A7FZj7v+d/sdmMqp/nOQwliLvUsJfDHW+k9Omg/a/EheAdgtzNs3hpfag6Ed950n" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/tether/1.4.0/js/tether.min.js" integrity="sha384-DztdAPBWPRXSA/3eYEEUWrWCy7G5KFbe8fFjk5JAIxUYHKkDx6Qin1DkWx51bBrb" crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.6/js/bootstrap.min.js" integrity="sha384-vBWWzlZJ8ea9aCX4pEW3rVHjgjt7zpkNpZk+02D9phzyeVkE+jo0ieGizqPLForn" crossorigin="anonymous"></script>


<ul class="nav nav-tabs" role="tablist">
  <li class="nav-item">
    <a class="nav-link active" data-toggle="tab" href="#home" role="tab">Home</a>
    <div class="arrow-down"></div>
  </li>
  <li class="nav-item">
    <a class="nav-link" data-toggle="tab" href="#profile" role="tab">Profile</a>
  </li>
  <li class="nav-item">
    <a class="nav-link" data-toggle="tab" href="#messages" role="tab">Messages</a>
  </li>
  <li class="nav-item">
    <a class="nav-link" data-toggle="tab" href="#settings" role="tab">Settings</a>
  </li>
</ul>

<div class="tab-content">
  <div class="tab-pane active" id="home" role="tabpanel">...</div>
  <div class="tab-pane" id="profile" role="tabpanel">...</div>
  <div class="tab-pane" id="messages" role="tabpanel">...</div>
  <div class="tab-pane" id="settings" role="tabpanel">...</div>
</div>

1 个解决方案

#1

Add a class to show the arrow, then add on click event to all menu, remove the previous arrow and add to the current tab.

添加一个类以显示箭头,然后将click事件添加到所有菜单,删除上一个箭头并添加到当前选项卡。

.active-arrow {
  display: block;
}

To center the arrow, you could use flexbox, and add margin-top to each arrow to position it right.

要使箭头居中,您可以使用flexbox,并为每个箭头添加margin-top以使其正确定位。

.nav-item {
  display: flex;
  align-items: center;
  justify-content: center;
}

$('ul a.nav-link').on('click', function(e) {
  $('.arrow-down').removeClass('active-arrow');
  $(this).next('.arrow-down').addClass('active-arrow');
})

.arrow-down {
  position: absolute;
  width: 0;
  height: 0;
  border-left: 15px solid transparent;
  border-right: 15px solid transparent;
  border-top: 15px solid white;
  display: none;
  margin-top: 28px;
}

.nav-item {
  display: flex;
  align-items: center;
  justify-content: center;
}

.active-arrow {
  display: block;
}

.nav-tabs {
  background-color: black;
}

.tab-content {
  background-color: #ccc
}

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.6/css/bootstrap.min.css" integrity="sha384-rwoIResjU2yc3z8GV/NPeZWAv56rSmLldC3R/AZzGRnGxQQKnKkoFVhFQhNUwEyJ" crossorigin="anonymous">
<script src="https://code.jquery.com/jquery-3.1.1.slim.min.js" integrity="sha384-A7FZj7v+d/sdmMqp/nOQwliLvUsJfDHW+k9Omg/a/EheAdgtzNs3hpfag6Ed950n" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/tether/1.4.0/js/tether.min.js" integrity="sha384-DztdAPBWPRXSA/3eYEEUWrWCy7G5KFbe8fFjk5JAIxUYHKkDx6Qin1DkWx51bBrb" crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.6/js/bootstrap.min.js" integrity="sha384-vBWWzlZJ8ea9aCX4pEW3rVHjgjt7zpkNpZk+02D9phzyeVkE+jo0ieGizqPLForn" crossorigin="anonymous"></script>


<ul class="nav nav-tabs" role="tablist">
  <li class="nav-item">
    <a class="nav-link active" data-toggle="tab" href="#home" role="tab">Home</a>
    <div class="arrow-down active-arrow"></div>
  </li>
  <li class="nav-item">
    <a class="nav-link" data-toggle="tab" href="#profile" role="tab">Profile</a>
    <div class="arrow-down"></div>
  </li>
  <li class="nav-item">
    <a class="nav-link" data-toggle="tab" href="#messages" role="tab">Messages</a>
    <div class="arrow-down"></div>
  </li>
  <li class="nav-item">
    <a class="nav-link" data-toggle="tab" href="#settings" role="tab">Settings</a>
    <div class="arrow-down"></div>
  </li>
</ul>

<div class="tab-content">
  <div class="tab-pane active" id="home" role="tabpanel">1</div>
  <div class="tab-pane" id="profile" role="tabpanel">2</div>
  <div class="tab-pane" id="messages" role="tabpanel">3</div>
  <div class="tab-pane" id="settings" role="tabpanel">4</div>
</div>