jQuery addClass example
Change class name on click in jQuery
HTML
<div class="box">
</div>CSS
.box { width:200px; height: 100px; border: 1px solid red; background:#000; position:relative; }
.box:after { content:''; width: 15px; height: 15px; border-radius: 50%; background:#0f0; top:calc(50% - 15px); border:2px solid #fff; right: -10px; display: block; position: absolute; }