JSFiddle - React, Tailwind, and code Playground
HTML
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
</head>
<body>
<div id="myContentToFill">old stuff</div>
</body>
</html>
JavaScript
$().ready(function(){
var str1="<div id='item1'><h2>This is a heading1</h2><p>This is a paragraph1.</p></div><div id='item2'><h2>This is a heading2</h2><p>This is another paragraph.</p></div><div id='lastdiv'>last</div>";
$('#myContentToFill').html(str1);
});