JSFiddle - React, Tailwind, and code Playground

HTML

<div id="result">

</div>

JavaScript

var elem = document.getElementById("result");
fetch('/echo/html/', {
  method: "POST",
  body: "html=" + encodeURIComponent("This is a test")
}).then(function(response) {
  return response.text();
}).then(function(string) {
  elem.innerHTML = string;
});