JSFiddle - React, Tailwind, and code Playground

HTML

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

CSS

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

JavaScript

function fading(){
    var increment = 0.045;
    var opacity = 0;
    var instance = window.setInterval(function() {
        document.getElementById('about').style.opacity = opacity
        opacity = opacity + increment;
        if(opacity > 1){
            window.clearInterval(instance);
        }
    },100)
}

fading();