JSFiddle - React, Tailwind, and code Playground

HTML

<div id="main">
     <div class="pre1">
      <div class="prop1">1</div>
      <div class="prop2">2</div>
      <div class="prop3">3</div>
     </div>
     <div class="pre2">
      <div class="prop1">1</div>
      <div class="prop2">2</div>
      <div class="prop3">3</div>
     </div>
     <div class="pre3">
      <div class="prop1">1</div>
      <div class="prop2">2</div>
      <div class="prop3">3</div>
     </div>
    </div>

JavaScript

var el = document.getElementById('main').firstElementChild;
    while (el) {
      var el2 = el.firstElementChild;
      while (el2) {
        if (el2.className == 'prop2')
          el2.textContent = 'hola';
	      el2 = el2.nextElementSibling;
      }
      el = el.nextElementSibling;
    }