I only update when I feel like it.

collapse（いわゆるアコーディオン）は、一般的に閉じるボタンなど使わずに閉じますが、敢えて、閉じるボタンで閉じる場合の覚書。

bootstrap4のCollapse
https://getbootstrap.com/docs/4.3/components/collapse/

HTML

<a class="btn btn-primary" data-toggle="collapse" href="#collapseExample" role="button" aria-expanded="false" aria-controls="collapseExample">Link with href</a>

<button class="btn btn-primary" type="button" data-toggle="collapse" data-target="#collapseExample" aria-expanded="false" aria-controls="collapseExample">Button with data-target</button>

<div class="collapse" id="collapseExample">
  <div class="card card-body">
    <p>Anim pariatur cliche reprehenderit, enim eiusmod high life accusamus terry richardson ad squid. Nihil anim keffiyeh helvetica, craft beer labore wes anderson cred nesciunt sapiente ea proident.</p>
    <p class="text-center mb-0"><a class="btn btn-link collapse-close" href="#">閉じる</a></p>
  </div>
</div>

Javascript/jQuery

$(function(){
  $('.collapse-close').click( function () {
    $(".collapse").collapse('hide');
  });
});