How to determine if a bootstrap collapse is opening or closing?

Question

If I have a bootstrap collapse how can I determine from a click event wether the collapse is opening or closing?

Here is my click event or maybe there is a better way then to use a click event?

$(document).on("click", "a.register-student-link", function() {     // do some stuff to check if opening or closing } 

<div>    <a [email protected] class="register-student-link" data-toggle="collapse" href=@spaceIdWith aria-expanded="false" aria-controls="collapseExample">                                                      Register Student                                                  </a>  </div>

Answer 1

Bootstrap uses the aria-expanded attribute to show true or false if the region is collapsed or not.

var isExpanded = $(collapsableRegion).attr("aria-expanded"); 

Answer 2

Try:

$('#collapseDiv').on('shown.bs.collapse', function () {     console.log("Opened")  });    $('#collapseDiv').on('hidden.bs.collapse', function () {     console.log("Closed")  });

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>  <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/js/bootstrap.min.js"></script>  <link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css" rel="stylesheet"/>  <div>    <a [email protected] class="register-student-link" data-toggle="collapse" href="#collapseDiv" aria-expanded="false" aria-controls="collapseExample">Register Student</a>  </div>    <div class="collapse" id="collapseDiv">This is the collapsible content!</div>

(based on https://stackoverflow.com/a/18147817/2033574 (Kevin mentioned) and http://www.bootply.com/73101)