JSFiddle - React, Tailwind, and code Playground
HTML
<p class="main"></p>
<div class="d"></div>JavaScript
var p = $('p.main').children().length;
var e = $('p.main').is(':empty');
var d = $('div.d').is(':empty');
console.log(p);
console.log(e);
console.log(d);