JSFiddle - React, Tailwind, and code Playground

HTML

<div class="test">Test</div>
<div class="test">Test</div>
<div class="test">Test</div>
<div class="test">Test</div>

JavaScript

Array.prototype.slice.call(
    document.getElementsByClassName("test")
).forEach(function(element) {
    element.style.color = "blue"
});