JSFiddle - React, Tailwind, and code Playground

JavaScript

//create custom test date
var d1 = new Date(2012, 9, 1, 13, 14, 0, 0);
//create current date
var d2 = new Date();
//get date times (ms)
var d1Time = (d1.getTime());
var d2Time = (d2.getTime());
//calculate the difference in date times
var diff = d2 - d1;
//create a new date using the time differences (starts at Jan 1, 1970)
var dDiff = new Date();
dDiff.setTime(diff);
//chop off 1970 and get year, month, day, and hour
var start = new Date(0);
var years = dDiff.getFullYear() - start.getFullYear();
var months = dDiff.getMonth() -  start.getMonth();
var days = dDiff.getDate() -  start.getDate();
var hours = dDiff.getHours() - start.getHours();;
console.log(years, months, days, hours);