JSFiddle - React, Tailwind, and code Playground

HTML

<div id="1">
    <div id="2">
        <div id="3"></div>
        <div id="4">
            <div id="5"></div>
        </div>
        <div id="6"></div>
    </div>
    <div id="7"></div>
    <div id="8">
        <div id="9">
            <div id="10">
                <div id="11"></div>
            </div>
        </div>
    </div>
</div>
<div id="log"></div>

JavaScript

var depthFirstTraversal = function($root, callback) {
    $root.children().each(function() {
        depthFirstTraversal($(this), callback);
    });
    callback($root);
};
depthFirstTraversal($("#1"), function($node) {
    $("#log").append('<br>' + $node.attr("id"));
});