JSFiddle - React, Tailwind, and code Playground

HTML

<p align="center"><font face="arial" size="-2">This free script provided by</font><br>
<font face="arial, helvetica" size="-2"><a href="http://javascriptkit.com">JavaScript
Kit</a></font></p>

JavaScript

var montharray=new Array("Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec")

function countup(yr,m,d){
var today=new Date()
var todayy=today.getYear()
if (todayy < 1000)
todayy+=1900
var todaym=today.getMonth()
var todayd=today.getDate()
var todaystring=montharray[todaym]+" "+todayd+", "+todayy
var paststring=montharray[m-1]+" "+d+", "+yr
var difference=(Math.round((Date.parse(todaystring)-Date.parse(paststring))/(24*60*60*1000))*1)
difference+=" days"
function formatNumber (difference) {
    return difference.toString().replace(/(\d)(?=(\d{3})+(?!\d))/g, "$1,")
}
document.write("It\'s been "+formatNumber(difference)+" since the launch of JavaScript Kit!")
}
//enter the count up date using the format year/month/day
countup(1997,12,05)