JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container-right">
  <h1>Title</h1>

</div>

JavaScript

function create(htmlStr) {
  var frag = document.createDocumentFragment(),
    temp = document.createElement('div');
  temp.innerHTML = htmlStr;
  while (temp.firstChild) {
    frag.appendChild(temp.firstChild);
  }
  return frag;
}

var target = document.querySelectorAll(".container-right");
var fragment = create(
  '<div class="freetext"><p>Some text that should be appended...</p></div>'
);
document.body.insertBefore(fragment, document.body.childNodes[0]);