JSFiddle - React, Tailwind, and code Playground

HTML

<div class="submenu">Hello</div>
<div class="submenu">Hello</div>
<div class="submenu">Hello</div>
<div class="submenu">Hello</div>
<div class="submenu">Hello</div>
<div class="submenu">Hello</div>

JavaScript

var submenus = document.getElementsByClassName("submenu");
	for (var i = 0; i < submenus.length; i++) {
	    submenus[i].onclick = function() {
	        alert(i);
	    }
	}