JSFiddle - React, Tailwind, and code Playground

HTML

<body>
    <div id="frameId">
      <ul>
        <li id="item1">Coffee</li>
        <li id="item2">Tea</li>
      </ul>
    </div>

    <p>Click the button get the HTML content of the iframe.</p>

    <textarea id="demo"></textarea><br/>

    <button onclick="myFunction()">Try it</button>

  <script>
    function myFunction() {
        var frameContent = document.getElementById("frameId").innerHTML;
        document.getElementById("demo").innerHTML = frameContent;
    }
  </script>
</body>