Date.SECOND = 1000;
Date.MINUTE = 60 * Date.SECOND;
Date.HOUR   = 60 * Date.MINUTE;
Date.DAY    = 24 * Date.HOUR;
Date.WEEK   =  7 * Date.DAY;

Date.prototype.getMonthDays = function() {
	var _md = new Array(31,28,31,30,31,30,31,31,30,31,30,31);
	var year = this.getFullYear();
	var month = this.getMonth();

	if (((0 == (year%4)) && ( (0 != (year%100)) || (0 == (year%400)))) && month == 1) {
		return 29;
	} else {
		return _md[month];
	}
};

Date.prototype.getWeekDay = function(week_starts_with) {
	do_day = this.getDay();
	rday = do_day - week_starts_with;
	if (rday < 0) {
		return (6+rday+1);
	} else {
		return rday;
	}
};

Date.prototype.isToday = function() {
	var now = new Date();
	
	if (now.getDate() != this.getDate()) {
		return false;
	}
	if (now.getMonth() != this.getMonth()) {
		return false;
	}
	if (now.getFullYear() != this.getFullYear()) {
		return false;
	}
	
	return true;
}


/**
* Returns the week number for this date. dowOffset is the day of week the week
* "starts" on for your locale - it can be from 0 to 6. If dowOffset is 1 (Monday),
* the week returned is the ISO 8601 week number.
* @param int dowOffset
* @return int
*/
Date.prototype.getWeek = function (dowOffset) {
/*getWeek() was developed by Nick Baicoianu at MeanFreePath: http://www.meanfreepath.com */

	dowOffset = typeof(dowOffset) == 'int' ? dowOffset : 0; //default dowOffset to zero
	
	var newYear = new Date(this.getFullYear(),0,1);
	var day = newYear.getDay() - dowOffset; //the day of week the year begins on
	day = (day >= 0 ? day : day + 7);
	var daynum = Math.floor((this.getTime() - newYear.getTime() - (this.getTimezoneOffset()-newYear.getTimezoneOffset())*60000)/86400000) + 1;
	var weeknum;
	var nYear, nday;
	
	//if the year starts before the middle of a week
	if(day < 4) {
		weeknum = Math.floor((daynum+day-1)/7) + 1;
		if(weeknum > 52) {
			nYear = new Date(this.getFullYear() + 1,0,1);
			nday = nYear.getDay() - dowOffset;
			nday = nday >= 0 ? nday : nday + 7;
/*if the next year starts before the middle of
the week, it is week #1 of that year*/
			weeknum = nday < 4 ? 1 : 53;
		}
	} else {
		weeknum = Math.floor((daynum+day-1)/7);
	}
	return weeknum;
};






// Simulates PHP's date function
Date.prototype.format = function(format) {
	var returnStr = '';
	var replace = Date.replaceChars;
	
	for (var i = 0; i < format.length; i++) {
		var curChar = format.charAt(i);
		if (replace[curChar])
			returnStr += replace[curChar].call(this);
		else
			returnStr += curChar;
	}
	return returnStr;
};
Date.replaceChars = {
	shortMonths: ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'],
	longMonths: ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'],
	shortDays: ['Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat'],
	longDays: ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'],
	
	// Day
	d: function() { return (this.getDate() < 10 ? '0' : '') + this.getDate(); },
	D: function() { return Date.replaceChars.shortDays[this.getDay()]; },
	j: function() { return this.getDate(); },
	l: function() { return Date.replaceChars.longDays[this.getDay()]; },
	N: function() { return this.getDay() + 1; },
	S: function() { return (this.getDate() % 10 == 1 && this.getDate() != 11 ? 'st' : (this.getDate() % 10 == 2 && this.getDate() != 12 ? 'nd' : (this.getDate() % 10 == 3 && this.getDate() != 13 ? 'rd' : 'th'))); },
	w: function() { return this.getDay(); },
	z: function() { return "Not Yet Supported"; },
	// Week
	W: function() { return "Not Yet Supported"; },
	// Month
	F: function() { return Date.replaceChars.longMonths[this.getMonth()]; },
	m: function() { return (this.getMonth() < 9 ? '0' : '') + (this.getMonth() + 1); },
	M: function() { return Date.replaceChars.shortMonths[this.getMonth()]; },
	n: function() { return this.getMonth() + 1; },
	t: function() { return "Not Yet Supported"; },
	// Year
	L: function() { return "Not Yet Supported"; },
	o: function() { return "Not Supported"; },
	Y: function() { return this.getFullYear(); },
	y: function() { return ('' + this.getFullYear()).substr(2); },
	// Time
	a: function() { return this.getHours() < 12 ? 'am' : 'pm'; },
	A: function() { return this.getHours() < 12 ? 'AM' : 'PM'; },
	B: function() { return "Not Yet Supported"; },
	g: function() { return this.getHours() == 0 ? 12 : (this.getHours() > 12 ? this.getHours() - 12 : this.getHours()); },
	G: function() { return this.getHours(); },
	h: function() { return (this.getHours() < 10 || (12 < this.getHours() < 22) ? '0' : '') + (this.getHours() < 10 ? this.getHours() + 1 : this.getHours() - 12); },
	H: function() { return (this.getHours() < 10 ? '0' : '') + this.getHours(); },
	i: function() { return (this.getMinutes() < 10 ? '0' : '') + this.getMinutes(); },
	s: function() { return (this.getSeconds() < 10 ? '0' : '') + this.getSeconds(); },
	// Timezone
	e: function() { return "Not Yet Supported"; },
	I: function() { return "Not Supported"; },
	O: function() { return (this.getTimezoneOffset() < 0 ? '-' : '+') + (this.getTimezoneOffset() / 60 < 10 ? '0' : '') + (this.getTimezoneOffset() / 60) + '00'; },
	T: function() { return "Not Yet Supported"; },
	Z: function() { return this.getTimezoneOffset() * 60; },
	// Full Date/Time
	c: function() { return "Not Yet Supported"; },
	r: function() { return this.toString(); },
	U: function() { return this.getTime() / 1000; }
}