JSFiddle - React, Tailwind, and code Playground

HTML

<div class="test">Test
    <div class="bu">Bu</div>test</div>

CSS

.test, .bu, .tu {
    border: 1px solid gray;
    padding: 10px;
    margin: 10px;
}

JavaScript

function hasClass(elem, className) {
    return elem.className.split(' ').indexOf(className) > -1;
}

document.addEventListener('click', function (e) {
		alert(e.target.className);
    if (hasClass(e.target, 'test')) {
        alert('has test');
    }
}, false);