How to animate the chevron glyphicon when toggling a bootstrap 3 panel?

Question

I have a working solution for a panel wrapped in an bootstrap 3 accordion.

How can I animate change of the chevron state from ">" to "^" with a 90 degrees rotation?

.panel-heading .accordion-toggle:after {
    font-family: 'Glyphicons Halflings';
    content: "\e114";
    float: right;
    color: grey;
}

.panel-heading .accordion-toggle.collapsed:after {
    content: "\e080";
}

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">


<div class="panel-group" id="accordion">
    <div class="panel panel-default">
        <div class="panel-heading">
            <h3 class="panel-title">
                <a class="accordion-toggle" data-toggle="collapse" data-parent="#accordion" href="#importationCollapse">Importation</a>
            </h3>
        </div>
        <div id="importationCollapse" class="panel-collapse collapse in">
            <div class="panel-body">
            <p>Content: blahblah</p>
            </div>
        </div>
    </div>
</div>

[EDIT] I am looking for a smooth rotation, I already how to change the chevron state.

Answer 1

You can simply replace

.panel-heading .accordion-toggle.collapsed:after {
    content: "\e080";
}

With the following

.panel-heading .accordion-toggle.collapsed:after {
    transform: rotateX(180deg);
}

That should do the trick, instead of using another character. Demo on Codepen

To animate the rotation you can add the following

.panel-heading .accordion-toggle:after {
    font-family: 'Glyphicons Halflings';
    content: "\e114";
    float: right;
    color: grey;
    transition: transform 0.5s;
    transform-origin: 8px 7px;
}

And to rotate along Z axis

.panel-heading .accordion-toggle.collapsed:after {
    transform: rotateZ(180deg);
}

You can experiment with transform-origin to get your desired result.

Demo on Codepen

Answer 2

Instead of changing content you can try with transition and transform: rotate() to get it done. check below snippet for reference.

.panel-heading .accordion-toggle:after {
  font-family: 'Glyphicons Halflings';
  content: "\e114";
  float: right;
  color: grey;
  transition: all 0.5s ease;
}

.panel-heading .accordion-toggle.collapsed:after {
  /*content: "\e080";*/
  transform: rotate(180deg);
}

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


<div class="panel-group" id="accordion">
  <div class="panel panel-default">
    <div class="panel-heading">
      <h3 class="panel-title">
        <a class="accordion-toggle" data-toggle="collapse" data-parent="#accordion" href="#importationCollapse">Importation</a>
      </h3>
    </div>
    <div id="importationCollapse" class="panel-collapse collapse in">
      <div class="panel-body">
        <p>Content: blahblah</p>
      </div>
    </div>
  </div>
</div>