JSFiddle - React, Tailwind, and code Playground

HTML

<button onclick="run()">run</button>
<div id="out"></div>
<div class="foo"></div>
<img class="bar">

JavaScript

function run() {
    document.querySelector('#out').innerHTML = JSON.stringify(parseDocument(document));
}

function parseDocument(doc) {
    var els = [].slice.call(doc.querySelectorAll('body *[class]'));
    
    return els.map(function(el) {
       var type = getType(el);
        return {
            class: el.className,
            type: type
        };
    });
}

function getType(el) {
    if(el.nodeName == 'img') {
        return 'image';
    }
    
    return 'other';
}