JSFiddle - React, Tailwind, and code Playground

HTML

<body>
<ul class="sp-methods">
  <li class="  ">Hide me</li>
  <li class="  ">Dont hide me</li>
</ul>
<script>
    document.addEventListener('DOMContentLoaded', function(){ 
        var el = document.querySelectorAll(".sp-methods li:first-child");
        for (i = 0; i < el.length; i++) {
            alert('sad')
            el[i].style.display='none';
        }  
    }, false);
</script>
</body>