JSFiddle - React, Tailwind, and code Playground

HTML

<!doctype html>
<html>
  <head>
    <title>My website</title>
  </head>
  <body>
    <h1 id="title">Hello world</h1>
    <script src="script.js"></script>
  </body>
</html>

JavaScript

let titleElement = document.getElementById("title");
titleElement.innerHTML = "Hello JavaScript";