JSFiddle - React, Tailwind, and code Playground

HTML

<ul id="ul1">
  <li>1</li>
  <li>2</li>
  <li>3</li>
  <li>
    <ul id="ul2">
      <li>4</li>
      <li>
        <ul id="ul3">
          <li>5</li>
          <li>6</li>
        </ul>
      </li>
      <li>7</li>
      <li>8</li>
    </ul>
  </li>
  <li>9</li>
</ul>

<div id="out"></div>

JavaScript

var eles = [];
$("#ul1").find("li").each(function (e) {
    eles.push(e);
});

$("#out").append(JSON.stringify(eles));