JSFiddle - React, Tailwind, and code Playground

HTML

<nav id="leftMenu">
  <ul class="menuList" data-title="О нас">
    <li>1</li>
    <li>2</li>
  </ul>
  <ul class="menuList" data-title="Выберите услугу">
    <li>3</li>
    <li>4</li>
  </ul>
  <ul class="menuList">
    <li>5</li>
    <li>6</li>
    <li>7</li>
  </ul>
</nav>

JavaScript

$('#leftMenu .menuList').each(function(){
	var title = $(this).data('title');
    if(title) $(this).prepend('<h4>'+title+'</h4>');
});