a/21589970/1636522

by wared

HTML

<ul>
    <li id="li1">1</li>
    <li id="li2">2</li>
    <li id="li3">3</li>
</ul>

JavaScript

var list = document.getElementsByTagName('ul')[0],
    items = list.getElementsByTagName('li'),
    i = items.length;
while (i--) list.appendChild(items[i]);