JSFiddle - React, Tailwind, and code Playground

HTML

<script>
    window.onload = function(){
       var body = window.document.querySelector("body");
       body.innerHTML = "HTML Document Loaded";
       body.style.backgroundColor = 'red';
       
       var header = window.document.querySelector("h1");
       header.innerHTML = "this is header";
       header.style.color = 'red';
        
    }
</script>