JSFiddle - React, Tailwind, and code Playground

HTML

<ul>

  <li>Café</li>
  <li>Mate</li>
  <li>Té</li>
</ul>

JavaScript

var d = document;
var ul = d.getElementsByTagName('ul');
for (var u = 0; u < ul.length; u++) {
  var li = ul[u].getElementsByTagName('li')
  for (var i = 0; i < li.length; i++) {
    li[i].className = 'Bebida';
  }
}