Date.prototype.js

Date.prototype.days = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'];
Date.prototype.months = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'];

Date.prototype.military = !/\b(am|pm)\b/i.test(new Date().toLocaleTimeString());
Date.prototype.military = false;

(function () {
	var date = new Date();
	date.setFullYear(2013, 10, 11);
	var string = date.toLocaleDateString();
	var notation = '';
	if (string.indexOf(11) == 0)
		notation = '%d.%m.%Y';
	else
		if (string.indexOf('11') < string.indexOf('13'))
			notation = '%m/%d/%y';
		else
			notation = '%Y-%m-%d';
	Date.prototype.notation = notation;
}());


Date.prototype.parse = function(s) {
	with(Date.prototype)
		var methods = [
			/*  0: nothing */ null,
			/*  1: year    */ function(x) {this.setFullYear(x < 100 ? (x < 70 ? 2000 + x : 1900 + x) : x);},
			/*  2: month   */ function(x) {this.setMonth(x - 1);},
			/*  3: date    */ setDate,
			/*  4: hours   */ setHours,
			/*  5: minutes */ setMinutes,
			/*  6: seconds */ setSeconds,
			/*  7: am/pm   */ function (x) { if (x.toLowerCase() == 'pm') this.setHours(this.getHours() + 12); },
			/*  8: 1th     */ function (x) { var y = this.getDate(); this.setDate(x); if (y > x) this.setMonth(this.getMonth() + 1); },
			/*  9: 2y      */ function (x) { this.setFullYear(this.getFullYear() + x); },
			/* 10: 3m      */ function (x) { this.setMonth(this.getMonth() + x); },
			/* 11: 4w      */ function (x) { this.setDate(this.getDate() + x * 7); },
			/* 12: 5d      */ function (x) { this.setDate(this.getDate() + x); }
		];
	
	var patterns = [
		// 10th 1y 2m 3w 4d
		{e: /(-?\d+)\s*\-?\s*th\w*/i, p: [8]},
		{e: /(-?\d+)\s*y\w*/i, p: [9]},
		{e: /(-?\d+)\s*m\w*/i, p: [10]},
		{e: /(-?\d+)\s*w\w*/i, p: [11]},
		{e: /(-?\d+)\s*d\w*/i, p: [12]},
		// {часы:минуты {am|pm}}
		{e: /(^|[^\d])([012]?\d|21|22|23)\s*([\:\-\.]+)\s*([0-5]?\d)\s*(am|pm)?/i, p: [0, 4, 0, 5, 7], time: 1},
		
		// {mm/dd/yy, mm/dd/yyyy} (USA, etc.)
		{e: /(^|[^\d])(0?\d|10|11|12)\s*(\/+)\s*([012]?\d|30|31)\s*\3\s*((19|20)?\d\d)([^\d]|$)/, p: [0, 2, 0, 3, 1]},
		// {dd.mm.yy, dd.mm.yyyy, /.,-} (EU, Russia, etc.)
		{e: /(^|[^\d])([012]?\d|30|31)\s*([\.\-\,\/]+)\s*(0?\d|10|11|12)\s*\3\s*((19|20)?\d\d)([^\d]|$)/, p: [0, 3, 0, 2, 1]},
		// {yyyy-mm-dd, yy-mm-dd} (Canada, China, Japan, etc.)
		{e: /(^|[^\d])((19|20)?\d\d)\s*([\.\-\/]+)\s*(0?\d|10|11|12)\s*\4\s*([012]?\d|30|31)([^\d]|$)/, p: [0, 1, 0, 0, 2, 3]}
	];
	
	var allDay = true;
	
	for (var i = patterns.length; i--;) {
		var pattern = patterns[i],
			match = s.match(pattern.e);
		
		if (match) {
			if (pattern.time)
				allDay = false;
			var pointers = pattern.p;
			
			for (var j = 0; j < pointers.length; j++)
				if (pointers[j] && match[j + 1]) {
					var value = parseInt(match[j + 1], 10);
					methods[pointers[j]].call(this, isNaN(value) ? match[j + 1] : value);
				}
			
			s = s.replace(pattern.e, '');
		}
	}
	
	this.allDay(allDay);
	
	return this;
}

Date.prototype.format = function(format) {
	if (!format)
		format = '%c';
	
	function leadingZeros(d) {
		return (d < 10 ? '0' : '') + d;
	}
	
	// like Python, more: http://docs.python.org/library/time.html#time.strftime
	var patterns = {
		//'a':																				// Locale’s abbreviated weekday name.
		'A':	function() { return this.days[this.getDay()]; },							// Locale’s full weekday name.
		//'b':																				// Locale’s abbreviated month name.
		'B':	function() { return this.months[this.getMonth()]; },						// Locale’s full month name.
		'c':	function() { return this.format('%x' + (this.allDay() ? '' : ' %X')); },	// Locale’s appropriate date and time representation.
		'd':	function() { return leadingZeros(this.getDate()); },						// Day of the month as a decimal number [01,31].
		'H':	function() { return leadingZeros(this.getHours()); },						// Hour (24-hour clock) as a decimal number [00,23].
		'I':	function() { return leadingZeros(this.getHours() % 12); },					// Hour (12-hour clock) as a decimal number [01,12].
		//'j':																				// Day of the year as a decimal number [001,366].
		'm':	function() { return leadingZeros(this.getMonth() + 1); },					// Month as a decimal number [01,12].
		'M':	function() { return leadingZeros(this.getMinutes()); },						// Minute as a decimal number [00,59].
		'p':	function() { return this.getHours() < 12 ? 'AM' : 'PM'; },					// Locale’s equivalent of either AM or PM.
		'S':	function() { return leadingZeros(this.getSeconds()); },						// Second as a decimal number [00,61].
		//'U':																				// Week number of the year (Sunday as the first day of the week) as a decimal number [00,53]. All days in a new year preceding the first Sunday are considered to be in week 0.
		//'w':																				// Weekday as a decimal number [0(Sunday),6].
		//'W':																				// Week number of the year (Monday as the first day of the week) as a decimal number [00,53]. All days in a new year preceding the first Monday are considered to be in week 0.
		'x':	function() { return this.format(this.notation); },							// Locale’s appropriate date representation.
		'X':	function() { return this.format(this.military ? '%H:%M' : '%I:%M %p'); },	// Locale’s appropriate time representation.
		'y':	function() { return leadingZeros(this.getFullYear() % 100); },				// Year without century as a decimal number [00,99].
		'Y':	function() { return '' + this.getFullYear(); },								// Year with century as a decimal number.
		//'Z':																				// Time zone name (no characters if no time zone exists).
	};
	
	var context = this,
		result = format,
		pattern;
	
	function replacer() {
		return patterns[pattern].call(context);
	}
	
	for (pattern in patterns)
		result = result.replace(
			'%' + pattern,
			replacer
		);
	
	return result;
}

Date.prototype.timestamp = function(timestamp) {
	if (timestamp)
		this.setTime(timestamp * 1000);
	return parseInt(this.valueOf() / 1000);
}

Date.prototype.allDay = function(value) {
	if (value == undefined)
		return this.getSeconds() == 1;
	this.setSeconds(value ? 1 : 0);
	return this;
}

Date.prototype.clone = function() {
	return new Date(this.valueOf());
}

Date.prototype.date = function() {
	return new Date(this.getFullYear(), this.getMonth(), this.getDate());
}