JSFiddle - React, Tailwind, and code Playground

HTML

<div id='parent_id'>
    <div> Please change my background</div>
    <div> me too</div>
    <div> me three </div>
    </div>
    <button onclick='changeme();'>Change 'em</button>

JavaScript

function changeme() {
    var nodes = document.getElementById('parent_id').childNodes;
    for(var i=0; i<nodes.length; i++) {
         if (nodes[i].nodeName.toLowerCase() == 'div') {
        nodes[i].style.background = '#f3f3f3';
         }
    }
}