Edit in JSFiddle

var html = document.getElementById('main').innerHTML;
document.getElementById('result').innerHTML = html;

<div id="main">
    <ul>
        <li>coffee</li>
        <li>coke</li>
        <li>red bull</li>
    </ul>
</div>
<textarea id="result" rows="6" cols="50"></textarea>

#main { display: none; }