jQuery addClass example

Change class name on click in jQuery

HTML

<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/select2/4.0.6-rc.1/css/select2.css">
<script src="https://cdnjs.cloudflare.com/ajax/libs/select2/4.0.6-rc.1/js/select2.js"></script>
<select id="mySelect" multiple="multiple">
  <option value="volvo">Volvo</option>
  <option value="saab">Saab</option>
  <option value="mercedes">Mercedes</option>
  <option value="audi">Audi</option>
</select>

CSS

body {
  background: #20262E;
  padding: 20px;
  font-family: Helvetica;
}

#banner-message {
  background: #fff;
  border-radius: 4px;
  padding: 20px;
  font-size: 25px;
  text-align: center;
  transition: all 0.2s;
  margin: 0 auto;
  width: 300px;
}

button {
  background: #0084ff;
  border: none;
  border-radius: 5px;
  padding: 8px 14px;
  font-size: 15px;
  color: #fff;
}

#banner-message.alt {
  background: #0084ff;
  color: #fff;
  margin-top: 40px;
  width: 200px;
}

#banner-message.alt button {
  background: #fff;
  color: #000;
}

JavaScript

$("#mySelect").select2({  
 width: '100%',
        allowClear: true,
        closeOnSelect: false
        
 }).on('select2:open', function () {
        let a = $(this).data('select2');
        if (!$('.select2-link').length) {
            a.$results.parents('.select2-results')
                .append('<div class="select2-link2 select2-close"><button>Close</button></div>')
                .on('click', function (b) {
                    
                    //Why does uncommenting this cause the select2 to close when selecting an item
                    //a.trigger('close');
                    
                });
        }
    });