JSFiddle - React, Tailwind, and code Playground

HTML

<ul id="listings">
  <li class="layer block color-blue" id="item-1">A</li>
  <li class="layer block color-red" id="item-2">B</li>
  <li class="layer block color-green" id="item-3">C</li>
</ul>

JavaScript

document.getElementById("listings").addEventListener("click", function(e) {
   var target = e.target || e.srcElement;
   alert(target.className);
});