Prototype ¬ Detail

author: LennyNero [+], Submitted: 08.23.05 7a • Last Edit: 07.04.08 12p

// Author: Cosimo Manfredonia
// www.cosimomanfredonia.it
Date.prototype.getRomanDate = function() {
	var monthDays = new Date(this.getFullYear(), this.getMonth()+1, 0).getDate();
	var date = this.getDate();
	var month = this.getMonth();
	var dayBefore = "pridie";
	var nDayBefore = "a. d.";	//  or "ante diem"
	var strYear = " Anno Domini "+arabToRoman(this.getFullYear());
	var nonae;
	var idus;
	if (month == 2 || month == 4 || month == 6 || month == 9) {
		nonae = 7;
		idus = 15;
	} else {
		nonae = 5;
		idus = 13;
	}
	if (monthDays == 29) {
		// Trivia
		// Why do we call "bissextile" an year that has 366 days?
		// A new day was inserted between 23rd end 24th Feb
		// 24th Feb was the sixth day before March kalends 'dies sextus ante Kalendas Martias'
		// the inserted day was called 'dies "bis sextus" ante Kalendas Martias'
		if (date == 24) {
			return nDayBefore+" bis VI Kalendas Martias"+strYear;
		} else if (date>24) {
			date--;
		}
		monthDays = 28;
	}
	if (date == 1) {
		return "Kalendis "+latinMonth(month, "g")+strYear;
	} else if (date<nonae-1) {
		return nDayBefore+" "+arabToRoman(nonae-date+1)+" Nonas "+latinMonth(month)+strYear;
	} else if (date == nonae-1) {
		return dayBefore+" Nonas "+latinMonth(month)+strYear;
	} else if (date == nonae) {
		return "Nonis "+latinMonth(month, "g")+strYear;
	} else if (date<idus-1) {
		return nDayBefore+" "+arabToRoman(idus-date+1)+" Idus "+latinMonth(month)+strYear;
	} else if (date == idus-1) {
		return dayBefore+" Idus "+latinMonth(month)+strYear;
	} else if (date == idus) {
		return "Idibus "+latinMonth(month, "g")+strYear;
	} else if (date<monthDays) {
		return nDayBefore+" "+arabToRoman(monthDays-date+2)+" Kalendas "+latinMonth((month<11) ? month+1 : 0)+strYear;
	} else if (date=monthDays) {
		return dayBefore+" Kalendas "+latinMonth((month<11) ? month+1 : 0)+strYear;
	}
	function latinMonth(month, theCase) {
		if (theCase == "g") {
			// genitive case
			var acc = false;
		} else {
			// accusative case - default value
			var acc = true;
		}
		switch (month) {
		case 0 :
			return acc ? "Ianuarias" : "Ianuariis";
		case 1 :
			return acc ? "Februarias" : "Februariis";
		case 2 :
			return acc ? "Martias" : "Martiis";
		case 3 :
			return acc ? "Apriles" : "Aprilibus";
		case 4 :
			return acc ? "Maias" : "Maiis";
		case 5 :
			return acc ? "Iunias" : "Iuniis";
		case 6 :
			return acc ? "Iulias" : "Iuliis";
		case 7 :
			return acc ? "Augustas" : "Augustis";
		case 8 :
			return acc ? "Septembres" : "Septembribus";
		case 9 :
			return acc ? "Octobres" : "Octobribus";
		case 10 :
			return acc ? "Novembres" : "Novembribus";
		case 11 :
			return acc ? "Decembres" : "Decembribus";
		}
	}
	function arabToRoman(num) {
		if (num>3999) {
			// this algorithm works if num <= 3999;
			return "????";
		} else {
			var tho = Math.floor(num/1000);
			var hun = Math.floor((num-tho*1000)/100);
			var ten = Math.floor((num-tho*1000-hun*100)/10);
			var uni = Math.floor(num-tho*1000-hun*100-ten*10);
			return toRoman(tho, 3)+toRoman(hun, 2)+toRoman(ten, 1)+toRoman(uni, 0);
		}
		function toRoman(dig, pow) {
			var str = '';
			var symbols = [];
			symbols[0] = ['I', 'V', 'X'];
			symbols[1] = ['X', 'L', 'C'];
			symbols[2] = ['C', 'D', 'M'];
			if (pow>2) {
				for (var i = 0; i<dig; i++) {
					str += 'M';
				}
				return str;
			} else {
				switch (dig) {
				case 1 :
					str = symbols[pow][0];
					break;
				case 2 :
					str = symbols[pow][0]+symbols[pow][0];
					break;
				case 3 :
					str = symbols[pow][0]+symbols[pow][0]+symbols[pow][0];
					break;
				case 4 :
					str = symbols[pow][0]+symbols[pow][1];
					break;
				case 5 :
					str = symbols[pow][1];
					break;
				case 6 :
					str = symbols[pow][1]+symbols[pow][0];
					break;
				case 7 :
					str = symbols[pow][1]+symbols[pow][0]+symbols[pow][0];
					break;
				case 8 :
					str = symbols[pow][1]+symbols[pow][0]+symbols[pow][0]+symbols[pow][0];
					break;
				case 9 :
					str = symbols[pow][0]+symbols[pow][2];
					break;
				}
				return str;
			}
		}
	}
};

usage

//Example:
today=new Date();
trace("today is -> "+today.getRomanDate());
day=new Date(2005, 1, 24);
trace("24/02/2005 is -> "+day.getRomanDate());
day=new Date(2004, 1, 24);
trace("...but");
trace("24/02/2004 is -> "+day.getRomanDate());