Date.prototype.format = function(str) {
	var output = [];
	function pad(c, s, l) {
		s = String(s);
		while (s.length < l)
			s = c + s;
		return s;
	}
	var dnames = [ "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday" ];
	var mnames = [ "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December" ];
	var suffixes = {};
	suffixes[1] = "st";
	suffixes[21]= "st";
	suffixes[31]= "st";
	suffixes[2] = "nd";
	suffixes[22]= "nd";
	suffixes[3] = "rd";
	suffixes[23]= "rd";
	
	for (var i = 0; i < str.length; i++) {
		switch (str.charAt(i)) {
			case "d": output.push(pad("0", this.getDate(), 2)); break;
			case "D": output.push(dnames[this.getDay()].substring(0, 3)); break;
			case "j": output.push(this.getDate()); break;
			case "l": output.push(dnames[this.getDay()]); break;
			case "N": output.push(this.getDay() + 1); break;
			case "S": if (suffixes[this.getDate()]) output.push(suffixes[this.getDate()]); else output.push("nd"); break;
			case "w": output.push(this.getDay()); break;
			case "z": 
				var d = new Date(this.getTime()); 
				d.setHours(0); 
				d.setMinutes(0);
				d.setSeconds(0);
				d.setMilliseconds(0);
				d.setMonth(0);
				d.setDate(1);
				var diff = Math.floor((this.getTime() - d.getTime()) / 86400000);
				output.push(diff);
				break;
			case "F": output.push(mnames[this.getMonth()]); break;
			case "m": output.push(pad(0, this.getMonth() + 1, 2)); break;
			case "M": output.push(mnames[this.getMonth()].substring(0, 3)); break;
			case "n": output.push(this.getMonth() + 1); break;
			case "t":
				var d = new Date();
				d.setMonth(this.getMonth());
				d.setYear(this.getFullYear());
				d.setDate(0);
				output.push(d.getDate());
				break;
			case "L":
				var d = new Date();
				d.setMonth(2);
				d.setYear(this.getFullYear());
				d.setDate(0);
				output.push(d.getDate() == 29 ? "1" : "0");
				break;
			case "Y": output.push(this.getFullYear()); break;
			case "y": output.push(String(this.getFullYear()).substring(2)); break;
			case "a": output.push(this.getHours() >= 12 ? 'pm' : 'am'); break;
			case "A": output.push(this.getHours() >= 12 ? 'PM' : 'AM'); break;
			case "g": var p = this.getHours() % 12; if (p == 0) p = 12; output.push(p); break;
			case "G": output.push(this.getHours()); break;
			case "h": var p = this.getHours() % 12; if (p == 0) p = 12; output.push(pad("0", p, 2)); break;
			case "H": output.push(pad("0", this.getHours(), 2)); break;
			case "i": output.push(pad("0", this.getMinutes(), 2)); break;
			case "s": output.push(pad("0", this.getSeconds(), 2)); break;
			case "u": output.push(pad("0", this.getMilliseconds() * 100, 2)); break;
			default: output.push(str.charAt(i));
		}
	}
	return output.join("");
}