JSFiddle - React, Tailwind, and code Playground

JavaScript

var date=new Date("2018-09-02")
document.body.innerHTML=calculateAge(date)

function calculateAge(date) { 
   var ageDifMs = Date.now() - date;
   var ageDate = new Date(ageDifMs); 
   return Math.abs(ageDate.getUTCFullYear() - 1970);
 }