JSFiddle - React, Tailwind, and code Playground

HTML

<div>jQuery object <span id="result_div"></span></div>
<div>jQuery.get <span id="result_div2"></span></div>
<div id="testing_child">&nbsp;</div>

JavaScript

jQuery(function($) {
    $('#result_div').text($.contains(document, $('#testing_child')).toString());
    $('#result_div2').text($.contains(document, $('#testing_child').get(0)).toString());
});