JSFiddle - React, Tailwind, and code Playground

JavaScript

var days_to_add = 5;
var $myyear = 2012;
var $mymonth = 11; // november
var $myday = 29;
var date = new Date($myyear,$mymonth-1,$myday);
date.setDate(date.getDate()+(days_to_add));
document.write(
         (date.getDate()<10 ? "0" : "") + date.getDate()
         +'/'+
         (date.getMonth()<9 ? "0" : "") + (date.getMonth()+1)
         +'/'+
         date.getFullYear() 
    );