JSFiddle - React, Tailwind, and code Playground

HTML

<ul class="b-menu__dropdown topnav">
	<li class="b-menu__item level2">
		<a>test 1</a>
		<b class="caret"></b>
		<ul class="ul_2">
			<li class="b-menu__item level3">
				<a>test2</a>
				<b class="caret"></b>
				<ul class="ul_3">
					<li class="b-menu__item level4">
						<a>.test3</a>
					</li>
				</ul>
			</li>
		</ul>
	</li>
	<li class="b-menu__item level2">lol</li>
	<li class="b-menu__item level2">
		<a>ppp</a>
		<ul class="ul_2">
			<li class="b-menu__item level3">
				<a>kkk</a>
			</li>
		</ul>
	</li>
</ul>

JavaScript

$(document).ready(function(){
	$('.b-menu__item').click(function(e){
		$(this).find('ul').slideToggle('fast');
		e.preventDefault();
	});
});