JSFiddle - React, Tailwind, and code Playground
by cncent454518
HTML
<div id="div1" class="greeting">
hello
</div>
<div id="div2" class="greeting big-font">
hey
</div>
JavaScript
var div1 = document.getElementById('div1')
var div2 = document.getElementById('div2')
div1.className = div1.className + " border";
div2.className = div2.className + " border";
alert(div1.className)
alert(div2.className)