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>