JSFiddle - React, Tailwind, and code Playground

HTML

<div id="level-1" class="foo">
    <div id="level-2" class="">
        <div id="level-3" class="foo">
            
        </div>
    </div>
</div>

<div id="level-a" class="foo">
    <div id="level-b">
        <div id="level-c" class="foo">
            
        </div>
    </div>
</div>

JavaScript

$.fn.findClosest = function(selector) {
     return this.is(selector) ? this.filter(selector).first() : this.find(selector).first();
 };


console.log($('#level-2').findClosest('.foo'))