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() %  12  ||  12 ; },
    G: function() { return this.getHours(); },
    h: function() { return ((this.getHours() %  12  ||  12 ) <  10  ? '0' : '') + (this.getHours() %  12  ||  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  ? '-' : '+') + (Math.abs(this.getTimezoneOffset() /  60 ) <  10  ? '0' : '') + (Math.abs(this.getTimezoneOffset() /  60 )) + '00'; },
    T: function() { var m = this.getMonth(); this.setMonth( 0 ); var result = this.toTimeString().replace(/^.+ \(?([^\)]+)\)?$/, '$1'); this.setMonth(m); return result; },
    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 ; }
};