Bootstrap 4 导航栏切换图标不出现

Visit: https://jsfiddle.net/8tpm4z00/ https://jsfiddle.net/8tpm4z00/

<div class="container">

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

  <a href="#" class="navbar-brand">KP</a>

  <div class="collapse navbar-collapse" id="myNavigation">
      <div class="navbar-nav">
        <a class="p-3 nav-item nav-link active " href="#">Home</a>
        <a class="p-3 nav-item nav-link " href="#">About</a>
        <a class="p-3 nav-item nav-link " href="#">Contact Me</a>
      </div><!-- <div class="navbar-nav"> -->
  </div><!-- <div class="collapse navbar-collapse"> -->

</div><!-- <div class="container"> -->

The .navbar-toggler-icon当菜单因移动响应而折叠时，不会出现在导航栏切换按钮上。

我已经搜索过这个问题并调整了 jquery 和 bootstrap 链接。通过将 jquery 链接放在 bootstrap 4 链接上方。但这似乎不起作用。外部库以与 jsfiddle 相同的顺序链接在我的 HTML 中。

Update:

navbar-inverseB4版本不再可用，您可以使用navbar-dark反而。

Use navbar-inverse bg-inverse代替.navbar-default

<section role="navigation">
  <nav class="navbar navbar-inverse bg-inverse navbar-toggleable-sm fixed-top"><!-- navbar-inverse -->

    <div class="container">

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

      <a href="#" class="navbar-brand">KP</a>

      <div class="collapse navbar-collapse" id="myNavigation">
          <div class="navbar-nav">
            <a class="p-3 nav-item nav-link active " href="#">Home</a>
            <a class="p-3 nav-item nav-link " href="#">About</a>
            <a class="p-3 nav-item nav-link " href="#">Contact Me</a>
          </div><!-- <div class="navbar-nav"> -->
      </div><!-- <div class="collapse navbar-collapse"> -->

    </div><!-- <div class="container"> -->

  </nav>
</section>

更新了小提琴 https://jsfiddle.net/8tpm4z00/6/