JSFiddle - React, Tailwind, and code Playground

HTML

<nav>
        <ul>
           <li><a href="#">Item</a></li>
           <li><a href="#">Item</a></li>
           <li><a href="#">Item</a></li>
           <li><a href="#">Item</a>
                 <ul>
                    <li><a href="#">Sub Item</a>
                    <ul>
                    <li><a href="#">Sub Item</a></li>
                    <li><a href="#">Sub Item</a></li>
                    <li><a href="#">Sub Item</a></li>
                 </ul>
                    </li>
                    <li><a href="#">Sub Item</a></li>
                    <li><a href="#">Sub Item</a></li>
                 </ul>
           </li>
           <li><a href="#">Item</a>
                 <ul>
                    <li><a href="#">Sub Item</a></li>
                    <li><a href="#">Sub Item</a></li>
                    <li><a href="#">Sub Item</a></li>
                 </ul>
           </li>
        </ul>
    </nav>

CSS

a{
  font-family:arial,helvetica;
  font-size:14px;
  text-decoration:none;
  color:#444;
}
nav{
  width:200px;
  border:1px solid #9e9e9e;
  border-radius:4px;
}

ul,li{
  margin:0;
  padding:0;
  list-type:none;
   position:relative;
}

li a{
  display:block;
  position:relative;
  padding:6px 12px;
  border-bottom:1px solid #9e9e9e;
  
}

ul ul>li>a{
  padding-left:24px;
}

li > a::after{
  display:block;
	content:'⇩';
	padding:4px 6px;
	text-align:center;
	width:20px;
	position:absolute;
	right:0;
	top:0;
}
li>a:only-child::after{
  content:'';
}

li>ul{
  display:none;
}
li.open ul{
  display:block;
  }
}
li.open>a::after{
  content:'⇧';
}

li.active > a{
  background-color:#efefef;
  
}

JavaScript

var nav = $('nav');
    
    nav.find('li>a').on('click',function(e){
      
        e.preventDefault();
        
        var $this = $(this);
        var $li = $this.parent();

        //set active state to clicked menu item:
        $li.addClass('active').siblings().removeClass('active open');

				//look if there is a UL after the A, if so it contains submenu:
        if($this.next().is('ul')){
            $li.toggleClass('open');
        }

    });