JSFiddle - React, Tailwind, and code Playground

HTML

<div class="leftsidebar_templ1">
                    <ul id="nav">
                        <li class="expanded"><a class="on">Form a Compalny</a>
                                <ul class="submuneu">
                                    <li><a>United Kingdom (UK)</a></li>
                                    <li><a>United States of America (USA)</a></li>
                                    <li><a>Classic Offshore</a></li>
                                    <li><a>Alternative offshore Companies</a></li>
                                </ul>
                        </li>

                        <li class="expanded"><a class="on">Office and address services</a>
                                <ul class="submuneu">
                                    <li><a>Lorem Ipsum is simply</a></li>
                                    <li><a>Contrary to popular belief</a></li>
                                    <li><a>The standard chunk</a></li>
                                    <li><a>There are many variations</a></li>
                                </ul>
                        </li>
                        <li class="expanded"><a class="on">Nominee Services</a>
                                <ul class="submuneu">
                                    <li><a>Lorem Ipsum is simply</a></li>
                                    <li><a>Contrary to popular belief</a></li>
                                    <li><a>The standard chunk</a></li>
                                    <li><a>There are many variations</a></li>
                                </ul>
                        </li>

                        <li class="expanded"><a class="on">Corporate Banking</a>
                                <ul class="submuneu">
                                    <li><a>Lorem Ipsum is simply</a></li>
                                    <li><a>Contrary to popular belief</a></li>
                                    <li><a>The standard chunk</a></li>
                                   ...

JavaScript

$(document).ready(function(){   
    $('ul li.expanded > a')
    .attr('data-active','0')
    .click(function(event){
       $('.submuneu').hide();    
        if($(this).attr('data-active')==0){
            $(this).parent().find('ul').slideToggle('slow');
            $(this).attr('data-active','1');
        }
        else
          $(this).attr('data-active','0');        
    });
        $('a.on').click(function(){
        $('a.on').removeClass("active");
        $(this).addClass("active");
    });

});