Parrent add class to parrent

Parrent add class to parrent.html

<div class="side-box">
  <h4 class="side-title">Schermdiogonaal <i class="fa fa-angle-down"></i></h4>
	<ul class="side-list">
		<li><label><input type="checkbox"><span> Check me out</span></label></li>
		<li><label><input type="checkbox"><span> Check me out</span></label></li>
		<li><label><input type="checkbox"><span> Check me out</span></label></li>
		<li><label><input type="checkbox"><span> Check me out</span></label></li>
		<li><label><input type="checkbox"><span> Check me out</span></label></li>
  </ul>
</div>
<div class="side-box">
	<h4 class="side-title">Processor <i class="fa fa-angle-down"></i></h4>
	<ul class="side-list">
		<li><label><input type="checkbox"><span> Check me out</span></label></li>
		<li><label><input type="checkbox"><span> Check me out</span></label></li>
		<li><label><input type="checkbox"><span> Check me out</span></label></li>
		<li><label><input type="checkbox"><span> Check me out</span></label></li>
		<li><label><input type="checkbox"><span> Check me out</span></label></li>
	</ul>
</div>
<div class="side-box">
	<h4 class="side-title">Merk <i class="fa fa-angle-down"></i></h4>
	<ul class="side-list">
		<li><label><input type="checkbox"><span> Check me out</span></label></li>
		<li><label><input type="checkbox"><span> Check me out</span></label></li>
		<li><label><input type="checkbox"><span> Check me out</span></label></li>
		<li><label><input type="checkbox"><span> Check me out</span></label></li>
		<li><label><input type="checkbox"><span> Check me out</span></label></li>
	</ul>
</div>

Parrent add class to parrent.js

$('.side-box .side-title').on({
    click: function (){
		$(this).parent().toggleClass('open');
    }
  });