JSFiddle - React, Tailwind, and code Playground
by orig
HTML
<div id="elem">
<div class="cls"></div>
</div>
<div id="output">
</div>
JavaScript
var output = $('#output');
function out(text) {
$('<div>').text(text).appendTo(output);
}
var elem = $('#elem');
out('IN .has '+elem.has('.cls').length);
out('IN :has '+elem.filter(':has(.cls)').length);
elem = elem.clone();
out('OUT .has '+elem.has('.cls').length);
out('OUT :has '+elem.filter(':has(.cls)').length);