JSFiddle - React, Tailwind, and code Playground

HTML

<div class="find_class mediumCell">
    <div class="new1">
        <div class="select1"></div>
    </div>
    <div class="new2">
        <div class="select2"></div>
    </div>
    <div class="new3">
        <div class="select3"></div>
    </div>
</div>

JavaScript

var find = $('div.find_class div:last').attr('class');
alert(find);