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
}

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");