Javascript DateTime Functions

dates.js

function getYearMonthDay(isoDateTime) {
	const year = date.getFullYear()
	const month = (date.getMonth() + 1 < 10 ? '0' : '') + (date.getMonth() + 1)
	const day = date.getDate();
	return year + '/' + month + '/' + day
}

function getDayMonthYear(isoDateTime) {
	const year = date.getFullYear()
	const month = (date.getMonth() + 1 < 10 ? '0' : '') + (date.getMonth() + 1)
	const day = date.getDate();
	return day + '/' + month + '/' + year
}

function getYearMonthDayWithHyphens(isoDateTime) {
	const year = date.getFullYear()
	const month = (date.getMonth() + 1 < 10 ? '0' : '') + (date.getMonth() + 1)
	const day = date.getDate();
	return year + '-' + month + '-' + day
}

function getOrdinalDate(isoDateTime: Date) {
	const date = isoDateTime.getDate();
	if (date == 11 || date == 12 || date == 13) return date + 'th'
	switch (date % 10) {
		case 1: return date + 'st'
		case 2: return date + 'nd'
		case 3: return date + 'rd'
		default: return date + 'th'
	}
}

function getDayName(isoDateTime: Date) {
	const days = [
		"Sunday",
		"Monday",
		"Tuesday",
		"Wednesday",
		"Thursday",
		"Friday",
		"Saturday"
	]
	return days[isoDateTime.getDay()]
}

function getMonthName(isoDateTime: Date) {
	const months = [
		"January", 
		"February", 
		"March", 
		"April", 
		"May", 
		"June",
		"July", 
		"August", 
		"September", 
		"October", 
		"November", 
		"December"
	];
	return months[isoDateTime.getMonth()]
}

function numberOfDaysBetweenNowAndAnother(isoDateTime: Date) {
	const currentDate = new Date().getTime();
	const destinationDate = isoDateTime.getTime();
	
	const numberOfSecondsBetweenDates = 
		Math.abs(destinationDate - currentDate)
	
	const numberOfDaysBetweenDates = 
		numberOfSecondsBetweenDates / (1000 * 3600 * 24)
	
	return Math.round(numberOfDaysBetweenDates * 10) / 10
}

function getTwelveHourTime(isoDateTime: Date) {
	let hour = isoDateTime.getHours();
	const minutes = isoDateTime.getMinutes();
	const meridiem = (hour < 12) ? 'am' : 'pm'
	
	if (hour > 12) hour = hour - 12
	else if (hour == 0) hour = 12
	
	return hour + ':' + minutes + meridiem
}