this.$el.querySelectorAll is not a function code example

Example: queryselectorall is not a function

<article class="article first">
  <div class="wrapper"> 
    <div class="oferts"> 
      <div class="pro"></div> 
      <h1>This is the Pro Version</h1>  
    </div>
    <div class="oferts"> 
      <div class="normal"></div> 
      <h1>This is the normal Version</h1>  
    </div>
  </div>
</article>


<!-- You will get a NodeList as Output -->
<!-- Try to do : console.log(typeof(oferts)) And you will see the type-->
<script>
var articleFirst = document.querySelectorAll("article.first");
console.log(articleFirst)
var oferts = articleFirst[0].querySelectorAll(".oferts");
console.log(oferts)
</script>