JSFiddle - React, Tailwind, and code Playground
by brigand
HTML
<div id="outer">
<div class="foo">
<div class="foo bar"></div>
</div>
<div class="bar"></div>
<div class="foo"></div>
</div>
JavaScript
let els = document.querySelector('#outer').querySelectorAll(':scope > .foo');
console.log(Array.from(els, el => el.className))