JSFiddle - React, Tailwind, and code Playground

HTML

<ul class="menu">
  <li>144</li>
    <ul class="sub-menu">
      <li>123</li>
      <li>123</li>
      <li>123</li>
      <li>123</li>
      <li>123</li>
      <li>123</li>
      <li>123</li>
      <li>123</li>
  </ul>
  <li>155</li>
    <ul class="sub-menu">
      <li>123</li>
      <li>123</li>
  </ul>
</ul>

JavaScript

$(document).ready(function() {
 
  $('.sub-menu').each(function(i, el) {
  	var height = $(el).height();
    
  	if (height > 120) {  
    	$(el).addClass('scroll')
  	}
		else {
    	$(el).removeClass('scroll')
		}
	});
  
});