JSFiddle - React, Tailwind, and code Playground

HTML

<div id="one"></div>
<div id="two"></div>
<div id="three"></div>
<div id="four"></div>

JavaScript

$('#one').append('<span>'); // Its this one which is not being inserted
$('#one').append('<span></span>');

$('<span>').appendTo('#three');
$('<span></span>').appendTo('#four');

alert( 'Number of spans: '+$('span').length+' (should be 4)' );