JSFiddle - React, Tailwind, and code Playground

HTML

<div id="about">
    about
</div>

CSS

div {
    width:100px;
    height:50px;
    background:red;
    text-align:center;
    line-height:50px;
    font-size:30px;
    opacity:0;
    
}

JavaScript

var myopacity = 0;

function MyFadeFunction() {
   if (myopacity<1) {
      myopacity += .075;
     setTimeout(function(){MyFadeFunction()},100);
   }
   document.getElementById('about').style.opacity = myopacity;
}

MyFadeFunction();