JSFiddle - React, Tailwind, and code Playground

HTML

<div id="content">Выделим этот элемент</div>
<div>fdvfdgfdsgg</div>
<div>5555555555</div>
<div>hhhhhhhhhhhh</div>
<div>fdvfdgfdsgg</div>

JavaScript

var elements = document.getElementsByTagName('div');
  for(var n in elements)
  {
  	elements[n].style.background = 'green';
  }