JSFiddle - React, Tailwind, and code Playground

HTML

<div id="a">A
    <div id="b">B
        <div id="c">C
            <div id="d">D
                <div id="e">E</div> <span id="f">F</span>

                <button>Bc</button> <span>1<span>2<span>3
                </span></span>
                </span>
            </div>
        </div>
    </div>
</div>

JavaScript

var isADescendentOf = function (child, parent) {
    if (child === parent) {
        return true;
    }
    if (child === null) {
        return false;
    }
    return isADescendentOf(child.parentNode, parent);
};


var nodes = document.querySelectorAll("*");

for (var i = 0; i < nodes.length; i++) {
    nodes[i].addEventListener("click", function (event) {
        alert(isADescendentOf(event.target, this));
    });
}