JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container">
    <div id="1">1</div>
    <div id="2">2</div>
</div>

CSS

div {
    width: 50em;
    height: 2em;
    background-color: #eee;
    text-align: center;
    margin: 1em;
}

JavaScript

document.getElementById('container').addEventListener('click', function(e) {
    var target = e.target || e.srcElement;
    alert(target.id);
});