JSFiddle - React, Tailwind, and code Playground

JavaScript

var firstDayTimestamp = Date.parse("2009/07/13 00:00:00" + "-0500") / 1000;


var enddate = '31/12/2011'; //DD/MM/YYYY
var split = enddate.split('/');
var date = new Date(split[2], split[1], split[0]); //Y M D
var timestamp = date.getTime();

document.write(firstDayTimestamp);