JSFiddle - React, Tailwind, and code Playground

HTML

<div class="crazy">Text</div>
<div class="crazy">Text</div>
<div class="crdazy">Different Text</div>
<div class="crazy life">Text</div>

JavaScript

function findByClass(matchClass) {
    var elems = document.getElementsByTagName('*');
    var resp = [];
    for (var i = 0; i < elems.length; i++) {
        if((" "+elems[i].className+" ").indexOf(" "+matchClass+" ") > -1) {
            resp.push(elems[i]);
        }
    }
    return resp;
}

window.onload = function () {
    var elementos = findByClass("crazy");
    for (var i = 0; i < elementos.length; i++) {
        console.log(elementos[i].innerHTML);
    }
}