dateFormat

dateformat.js

var startTime = new Date();

function dateFormat(timestamp, past, in24Hours) {

	timestamp = isNaN(Number(timestamp)) ? timestamp : Number(timestamp);

	let formatedString = '';

	let listMonths 	= ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'],
		weekdays 	= ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'];

	let nowDate 		= new Date(),
		timestampDate 	= new Date(timestamp),
		elapsedMin 		= (nowDate - timestampDate) / 1000 / 60,
		elapsedHours;

	elapsedHours = Math.floor(elapsedMin / 60)
	elapsedMin = Math.floor(elapsedMin);

	let ordinal = function(number) {
		let b = number % 10,
			output = (~~(number % 100 / 10) === 1) ? 'th' :
			(b === 1) ? 'st' :
			(b === 2) ? 'nd' :
			(b === 3) ? 'rd' : 'th';
		return output;
	}

	let oneDigitNumber = function(num) {
	  num = '' + num;
	  return (num.indexOf('0') == 0 && num != '0') ? num.substring(1) : num;
	}

	let twoDigitNumber = function(num) {
	  num = Number(num);
	  return isNaN(num) ? '00' : (((num < 10) ? '0' : '') + num);
	}

	let hours = timestampDate.getHours();

	let dateParts = {
		month: twoDigitNumber(timestampDate.getMonth() + 1),
		date: twoDigitNumber(timestampDate.getDate()),
		year: twoDigitNumber(timestampDate.getFullYear()),
		day: timestampDate.getDay(),
		hour24: hours,
		hour12: hours,
		minutes: twoDigitNumber(timestampDate.getMinutes()),
		ampm: 'AM'
	}

	// Format the date
	dateParts.ordinal = ordinal(dateParts.date);
	dateParts.date_1 = oneDigitNumber(dateParts.date);

	// Format minutes
	dateParts.minutes_1 = oneDigitNumber(dateParts.minutes)

	// Format hours
	if (dateParts.hour24 > 11) {
		dateParts.ampm = 'PM';
	}

	dateParts.hour24 = twoDigitNumber(dateParts.hour24);
	dateParts.hour24_1 = oneDigitNumber(dateParts.hour24);

	if (dateParts.hour12 == 0) {
		dateParts.hour12 = 12;
	}

	if (dateParts.hour12 > 12) {
		dateParts.hour12 = dateParts.hour12 - 12;
	}

	dateParts.hour12 = twoDigitNumber(dateParts.hour12);
	dateParts.hour12_1 = oneDigitNumber(dateParts.hour12);

	// Format the elapsed time (X m ago or X h ago)
	if (elapsedHours < 1) {
		dateParts.elapsed = oneDigitNumber(elapsedMin) + 'm';
	} else {
		dateParts.elapsed = oneDigitNumber(elapsedHours) + 'h';
	}

	let patternReplace = function(formattedPart) {

		let weekDay 	= weekdays[dateParts.day],
			month 		= listMonths[Number(dateParts.month) - 1],
			monthShort 	= month.substring(0, 3),
			yearShort 	= dateParts.year.substring(2),
			weekDayMid 	= weekDay.substring(0, 3),
			weekDayShort = weekDay.substring(0, 2),
			amPmLowercase = dateParts.ampm.toLowerCase();

		formattedPart = formattedPart
					// AM/PM - am/pm
					.replace(/AA/g, dateParts.ampm)
					.replace(/aa/g, amPmLowercase)

					// Hours (24)
					.replace(/HH/g, dateParts.hour24)
					.replace(/H/g, dateParts.hour24_1)

					// Hours (12)
					.replace(/hh/g, dateParts.hour12)
					.replace(/h/g, dateParts.hour12_1)

					// Minutes
					.replace(/II/g, dateParts.minutes)
					.replace(/I/g, dateParts.minutes_1)

					// Date
					.replace(/DD/g, dateParts.date)
					.replace(/D/g, dateParts.date_1)

					// Ordinal for date
					.replace(/O/g, dateParts.ordinal)

					// Year
					.replace(/YYYY/g, dateParts.year)
					.replace(/YY/g, yearShort)

					// Elapsed time (Hours and Minutes)
					.replace(/GG/g, dateParts.elapsed)

					// Month
					.replace(/MM/g, month)
					.replace(/M/g, monthShort)

					// Week day
					.replace(/EEEE/g, weekDay)
					.replace(/EEE/g, weekDayMid)
					.replace(/EE/g, weekDayShort);

		return formattedPart;
	}

	let formatParts = function(pattern) {

		let formatPatternParts = pattern.replace('\\\'', '%Q%')
						.replace('\'\'', '%Q%')
						.split('\'');
		for (let i = 0; i < formatPatternParts.length; i++) {
			if (i % 2 == 0) {
				formatPatternParts[i] = patternReplace(formatPatternParts[i]);
			}
		}

		return formatPatternParts.join('').replace('%Q%', '\'');

	}

	if (elapsedHours < 24 && in24Hours) {
		formatedString = formatParts(in24Hours);
	} else {
		formatedString = formatParts(past);
	}
	return formatedString;

}

let t = 'Fri Jan 20 2017 22:33:28 GMT+1100 (AEDT)';
//let t = '1484897633537';


for (var i=0;i<1000;i++) {
	dateFormat(t, 'DD M ', 'GG \'ago\'');
	dateFormat(t, 'EEE, DD M');
	dateFormat(t, 'DDO M YY HH:II');
	dateFormat(t, 'hh:Iaa');
	dateFormat(t, 'GG \'ago\'');
}


/*
	AA - AM/PM
	aa - am/pm
	HH - hours (24) - 2 digits
	H - hours (24) - 1 digit
	hh - hours (12) - 2 digits
	h - hours (12) - 1 digit
	II - minutes - 2 digits
	I - minutes - 1 digit
	DD - date - 2 digits
	D - date - 1 digit
	O - date - ordinal
	MM - month - Long name
	M - month - Short name
	EEEE - week - long name
	EEE - week - 3 letters name
	EE - week - 2 letters name
	YYYY - year - Long
	YY - year - Short
	GG - elapse min/hours
*/


// later record end time
var endTime = new Date();

// time difference in ms
var timeDiff = endTime - startTime;
timeDiff /= 1000;

console.log(timeDiff);