JSFiddle - React, Tailwind, and code Playground

HTML

<div id="checkboxlist" >
    <ul class="checkboxlist_list">
        <li>
            <input type="checkbox" class="checkbox keys" name="keys" value="150" />Keys<br>
        </li>
        <li>
            <input type="checkbox" class="checkbox elec_guit" name="elec_guit" value="150" />Electric Guitar<br>
        </li>
        <li>
            <input type="checkbox" class="checkbox acou_guit" name="acou_guit" value="150" />Acoustic Guitar<br>
        </li>
        <li>
            <input type="checkbox" class="checkbox bass" name="bass" value="150" />Bass<br>
        </li>
        <li>
            <input type="checkbox" class="checkbox drums" name="drums" value="150" />Drums<br>
        </li>
    </ul>
</div>
Summary:<br>
<div class="summary_musicians"></div>

JavaScript

$('.checkbox').change(function() {
    $(".summary_musicians").html(function() {
        return $('.checkbox:checked').map(function() {
               return this.nextSibling.nodeValue;
        }).get().join(', ');
    });
});