fecha.format(<Date Object>, <String Format>);

// Custom formats
fecha.format(new Date(2015, 10, 20), 'DDDD MMMM Do, yyy'); // 'Friday November 20th, 2015'
fecha.format(new Date(1998, 5, 3, 15, 23, 10, 350), 'YYYY-MM-DD hh:mm:ss.SSS A'); // '1998-06-03 03:23:10.350 PM'

// Named masks
fecha.format(new Date(2015, 10, 20), 'mediumDate'); // 'Nov 20, 2015'
fecha.format(new Date(2015, 2, 10, 5, 30, 20), 'shortTime'); // '05:30'

// Literals
fecha.format(new Date(2001, 2, 5, 6, 7, 2, 5), '[on] MM-dd-yyyy [at] HH:mm'); // 'on 03-05-2001 at 06:07'

// Custom formats
fecha.parse('February 3rd, 2014', 'MMMM d, yyyy'); // new Date(2014, 1, 3)
fecha.parse('10-12-10 14:11:12', 'YY-MM-DD HH:mm:ss'); // new Date(2010, 11, 10, 14, 11, 12)

// Named masks
fecha.parse('5/3/98', 'shortDate'); // new Date(1998, 4, 3)
fecha.parse('November 4, 2005', 'longDate'); // new Date(2005, 10, 4)

// Override fecha.i18n to support any language
fecha.i18n = {
    dayNamesShort: ['Sun', 'Mon', 'Tue', 'Wed', 'Thur', 'Fri', 'Sat'],
    dayNames: ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'],
    monthNamesShort: ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'],
    monthNames: ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'],
    amPm: ['am', 'pm'],
    // D is the day of the month, function returns something like...  3rd or 11th
    DoFn: function (D) {
        return D + [ 'th', 'st', 'nd', 'rd' ][ D % 10 > 3 ? 0 : (D - D % 10 !== 10) * D % 10 ];
    }
}

fecha.masks = {
    default: 'DDD MMM dd YYYY HH:mm:ss',
    shortDate: 'M/d/YY',
    mediumDate: 'MMM d, yyyy',
    longDate: 'MMMM d, yyyy',
    fullDate: 'DDDD, MMMM d, yyyy',
    shortTime: 'HH:mm',
    mediumTime: 'HH:mm:ss',
    longTime: 'HH:mm:ss.SSS'
};

// Create a new mask
fecha.masks.myMask = 'HH:mm:ss yy/MM/dd';

// Use it
fecha.format(new Date(2014, 5, 6, 14, 10, 45), 'myMask'); // '14:10:45 14/06/06'