JSFiddle - React, Tailwind, and code Playground
HTML
<ul class="top">
<li>A</li>
<li>B</li>
<li>
<ul>
<li>1</li>
<li>2</li>
</ul>
</li>
</ul>
<div></div>
JavaScript
$("div").append($(".top").children().map(function(k, v){
if($(this).children().length == 0)
return this;
}).clone());