Bootstrap Collapse does not work

Question

I’m doing the portfolio challenge in freecodecamp. In the menu part I can’t get it to close on smaller screens. The menu closes but clicking on the icon it does not open and shows the items. Where I went wrong?

link to codepen

<nav class="navbar navbar-toggleable-md navbar-inverse bg-inverse">
  <button class="navbar-toggler navbar-toggler-right" type="button" data-toggle="collapse" data-target="#navbarCollapse" aria-controls="navbarCollapse" aria-expanded="false" aria-label="Toggle navigation">
      <span class="navbar-toggler-icon"></span>
    </button>
  <a class="navbar-brand" href="#">Portfolio</a>

  <div class="collapse navbar-collapse" id="navbarCollapse">
    <ul class="navbar-nav mr-auto">
      <li class="nav-item active">
        <a class="nav-link" href="#">About</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Images</a>
      </li>
    </ul>
    <ul class="navbar-nav">
      <li class="nav-item">
        <a class="nav-link" href="#">View on github</a>
      </li>
    </ul>
  </div>
</nav>

<div class="container">
  <h1>Hello World</h1>
</div>

Answer 1

You need some external files: jQuery2.1.1 and bootstrap.js

Now Collapse will work: Read more on Get Bootstrap

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<!-- Latest compiled and minified CSS -->
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">

<!-- Optional theme -->
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap-theme.min.css" integrity="sha384-rHyoN1iRsVXV4nD0JutlnGaslCJuC7uwjduW9SVrLvRYooPp2bWYgmgJQIXwl/Sp" crossorigin="anonymous">

<!-- Latest compiled and minified JavaScript -->
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js" integrity="sha384-Tc5IQib027qvyjSMfHjOMaLkfuWVxZxUPnCJA7l2mCWNIpG9mGCD8wGNIcPD7Txa" crossorigin="anonymous"></script>


<nav class="navbar navbar-toggleable-md navbar-inverse bg-inverse">
  <button class="navbar-toggler navbar-toggler-right" type="button" data-toggle="collapse" data-target="#navbarCollapse" aria-controls="navbarCollapse" aria-expanded="false" aria-label="Toggle navigation">
  <span class="navbar-toggler-icon"></span>
</button>
  <a class="navbar-brand" href="#">Portfolio</a>

  <div class="collapse navbar-collapse" id="navbarCollapse">
    <ul class="navbar-nav mr-auto">
      <li class="nav-item active">
        <a class="nav-link" href="#">About</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Images</a>
      </li>
    </ul>
    <ul class="navbar-nav">
      <li class="nav-item">
        <a class="nav-link" href="#">View on github</a>
      </li>
    </ul>
  </div>