JSFiddle - React, Tailwind, and code Playground

HTML

<ul>
	<li><a href="#" onclick="toggle(1);" >one</a>
		<ul class="submenu">
			<li>sacd</li>
			<li>safsdf</li>
		</ul>
	</li>
	
</ul>

CSS

.submenu {
	display: none;
}

JavaScript

function toggle(n) {
    var menus = document.getElementsByClassName("submenu");
    for(var i=0;i<menus.length;i++){
        if((i == (n-1)) && (menus[i].style.display != "block")){
            menus[i].style.display = "block";
        }else{
            menus[i].style.display = "none";
        }
    } 
};