JSFiddle - React, Tailwind, and code Playground
by Yure Pereira
HTML
<li style="display:none;" id="12-05-2016">Para o dia: 12-05-2016
<ul><li id="08:00"> Esta hora esta indisponivel: 08:00</li></ul>
<ul><li id="09:00"> Esta hora esta indisponivel: 09:00</li></ul>
</li>
<div id="datatime"></div>
<li style="display:none;" id="13-05-2016">Para o dia: 13-05-2016
</li>
JavaScript
var pai = document.getElementById('12-05-2016'),
filhos = pai.getElementsByTagName('li');