strftime/strftime.js

//
// strftime
// github.com/samsonjs/strftime
// @_sjs
//
// Copyright 2010 - 2013 Sami Samhuri <sami@samhuri.net>
//
// MIT License
// http://sjs.mit-license.org
//

;
(function () {
    //// Where to export the API
    var namespace;

    try {
        // CommonJS / Node module
        namespace = module.exports = strftime;
    } catch (error) {
        // Browsers and other environments
        // Get the global object. Works in ES3, ES5, and ES5 strict mode.
        namespace = new Function('return this')();
    }

    var DefaultLocale = {
        days: 'Sunday Monday Tuesday Wednesday Thursday Friday Saturday'.split(' '),
        shortDays: 'Sun Mon Tue Wed Thu Fri Sat'.split(' '),
        months: 'January February March April May June July August September October November December'.split(' '),
        shortMonths: 'Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec'.split(' '),
        AM: 'AM',
        PM: 'PM',
        am: 'am',
        pm: 'pm'
    };

    var RequiredDateMethods = [
        'getTime',
        'getTimezoneOffset',
        'getDay',
        'getDate',
        'getMonth',
        'getFullYear',
        'getYear',
        'getHours',
        'getMinutes',
        'getSeconds'
    ];

    function strftime(fmt, d, locale) {
        return _strftime(fmt, d, locale);
    }

    function strfTimeTZ(fmt, d, locale, timezone) {
        var _locale = locale;
        var _timezone = timezone;

        if ((typeof locale === 'number' || typeof locale === 'string') && timezone == null) {
            _timezone = locale;
            _locale = undefined;
        }

        return _strftime(fmt, d, _locale, {
            timezone: _timezone
        });
    }

    function strftimeUTC(fmt, d, locale) {
        return _strftime(fmt, d, locale, {
            utc: true
        });
    }

    function localizedStrftime(locale) {
        return function (fmt, d, options) {
            return _strftime(fmt, d, locale, options);
        };
    }

    // d, locale, and options are optional, but you can't leave
    // holes in the argument list. If you pass options you have to pass
    // in all the preceding args as well.
    //
    // options:
    //   - locale   [object] an object with the same structure as DefaultLocale
    //   - timezone [number] timezone offset in minutes from GMT
    function _strftime(format, d, locale, options) {
        var _options = options || {};
        var _locale = locale;
        var _d = d;

        // d and locale are optional so check if d is really the locale
        if (_d && !quacksLikeDate(_d)) {
            _locale = _d;
            _d = undefined;
        }

        _d = _d || new Date();

        _locale = _locale || DefaultLocale;
        _locale.formats = _locale.formats || {};

        // Hang on to this Unix timestamp because we might mess with it directly below.
        var timestamp = _d.getTime();
        var tz = _options.timezone;
        var tzType = typeof tz;

        if (_options.utc || tzType === 'number' || tzType === 'string') {
            _d = dateToUTC(_d);
        }

        if (tz) {
            // ISO 8601 format timezone string, [-+]HHMM
            // Convert to the number of minutes and it'll be applied to the date below.
            if (tzType === 'string') {
                var sign = tz[0] === '-' ? -1 : 1;
                var hours = parseInt(tz.slice(1, 3), 10);
                var mins = parseInt(tz.slice(3, 5), 10);

                tz = sign * (60 * hours) + mins;
            }

            _d = new Date(_d.getTime() + (tz * 60000));
        }

        // Most of the specifiers supported by C's strftime, and some from Ruby.
        // Some other syntax extensions from Ruby are supported: %-, %_, and %0
        // to pad with nothing, space, or zero (respectively).
        return format.replace(/%([-_0]?.)/g, function (_, c) {
            var padding;
            var _c = c;

            if (_c.length === 2) {
                switch (_c[0]) {
                    // omit padding
                    case '-':
                        padding = '';
                        break;

                    // pad with space
                    case '_':
                        padding = ' ';
                        break;

                    // pad with zero
                    case '0':
                        padding = '0';
                        break;

                    // unrecognized, return the format
                    default:
                        return _;
                }

                _c = _c[1];
            }

            switch (_c) {
                // Examples for new Date(0) in GMT

                // 'Thursday'
                case 'A':
                    return _locale.days[_d.getDay()];

                // 'Thu'
                case 'a':
                    return _locale.shortDays[_d.getDay()];

                // 'January'
                case 'B':
                    return _locale.months[_d.getMonth()];

                // 'Jan'
                case 'b':
                    return _locale.shortMonths[_d.getMonth()];

                // '19'
                case 'C':
                    return pad(Math.floor(_d.getFullYear() / 100), padding);

                // '01/01/70'
                case 'D':
                    return _strftime(_locale.formats.D || '%m/%d/%y', _d, _locale);

                // '01'
                case 'd':
                    return pad(_d.getDate(), padding);

                // '01'
                case 'e':
                    return _d.getDate();

                // '1970-01-01'
                case 'F':
                    return _strftime(_locale.formats.F || '%Y-%m-%d', _d, _locale);

                // '00'
                case 'H':
                    return pad(_d.getHours(), padding);

                // 'Jan'
                case 'h':
                    return _locale.shortMonths[_d.getMonth()];

                // '12'
                case 'I':
                    return pad(hours12(_d), padding);

                // '000'
                case 'j':
                    var y = new Date(_d.getFullYear(), 0, 1);
                    var day = Math.ceil((_d.getTime() - y.getTime()) / (1000 * 60 * 60 * 24));
                    return pad(day, null, 3);

                // ' 0'
                case 'k':
                    return pad(_d.getHours(), padding == null ? ' ' : padding);

                // '000'
                case 'L':
                    return pad(Math.floor(timestamp % 1000), null, 3);

                // '12'
                case 'l':
                    return pad(hours12(_d), padding == null ? ' ' : padding);

                // '00'
                case 'M':
                    return pad(_d.getMinutes(), padding);

                // '01'
                case 'm':
                    return pad(_d.getMonth() + 1, padding);

                // '\n'
                case 'n':
                    return '\n';

                // '1st'
                case 'o':
                    return String(_d.getDate()) + ordinal(_d.getDate());

                // 'am'
                case 'P':
                    return _d.getHours() < 12 ? _locale.am : _locale.pm;

                // 'AM'
                case 'p':
                    return _d.getHours() < 12 ? _locale.AM : _locale.PM;

                // '00:00'
                case 'R':
                    return _strftime(_locale.formats.R || '%H:%M', _d, _locale);

                // '12:00:00 AM'
                case 'r':
                    return _strftime(_locale.formats.r || '%I:%M:%S %p', _d, _locale);

                // '00'
                case 'S':
                    return pad(_d.getSeconds(), padding);

                // '0'
                case 's':
                    return Math.floor(timestamp / 1000);

                // '00:00:00'
                case 'T':
                    return _strftime(_locale.formats.T || '%H:%M:%S', _d, _locale);

                // '\t'
                case 't':
                    return '\t';

                // '00'
                case 'U':
                    return pad(weekNumber(_d, 'sunday'), padding);

                // '4'
                case 'u':
                    var day = _d.getDay();
                    return day === 0 ? 7 : day; // 1 - 7, Monday is first day of the week

                // '1-Jan-1970'
                case 'v':
                    return _strftime(_locale.formats.v || '%e-%b-%Y', _d, _locale);

                // '00'
                case 'W':
                    return pad(weekNumber(_d, 'monday'), padding);

                // '4'
                case 'w':
                    return _d.getDay(); // 0 - 6, Sunday is first day of the week

                // '1970'
                case 'Y':
                    return _d.getFullYear();

                // '70'
                case 'y':
                    return String(_d.getFullYear()).slice(-2);

                // 'GMT'
                case 'Z':
                    if (_options.utc) {
                        return 'GMT';
                    } else {
                        var tzString = _d.toString().match(/\((\w+)\)/);
                        return tzString && tzString[1] || '';
                    }

                // '+0000'
                case 'z':
                    if (_options.utc) {
                        return '+0000';
                    } else {
                        var off = typeof tz === 'number' ? tz : -_d.getTimezoneOffset();
                        return (off < 0 ? '-' : '+') + pad(Math.abs(off / 60)) + pad(off % 60);
                    }

                default:
                    return _c;
            }
        });
    }

    function dateToUTC(d) {
        var msDelta = (d.getTimezoneOffset() || 0) * 60000;

        return new Date(d.getTime() + msDelta);
    }

    function quacksLikeDate(x) {
        var index = RequiredDateMethods.length;

        while (index--) {
            if (typeof x[RequiredDateMethods[index]] !== 'function') {
                return false;
            }
        }

        return true;
    }

    // Default padding is '0' and default length is 2, both are optional.
    function pad(n, padding, length) {
        var _padding = padding == null ? '0' : padding;
        var _n = String(n);
        var _length = length || 2;

        // padding may be an empty string, don't loop forever if it is
        if (_padding) {
            while (_n.length < _length) {
                _n = _padding + _n;
            }
        }

        return _n;
    }

    function hours12(d) {
        var hour = d.getHours();

        if (hour === 0) {
            hour = 12;
        } else if (hour > 12) {
            hour -= 12;
        }

        return hour;
    }

    // Get the ordinal suffix for a number: st, nd, rd, or th
    function ordinal(n) {
        var i = n % 10;
        var ii = n % 100;

        if ((ii >= 11 && ii <= 13) || i === 0 || i >= 4) {
            return 'th';
        }

        switch (i) {
            case 1:
                return 'st';
            case 2:
                return 'nd';
            case 3:
                return 'rd';
        }
    }

    // firstWeekday: 'sunday' or 'monday', default is 'sunday'
    // Pilfered & ported from Ruby's strftime implementation.
    function weekNumber(d, firstWeekday) {
        var firstDayOfYear = new Date(d.getFullYear(), 0, 1);
        // This works by shifting the weekday back by one day if we
        // are treating Monday as the first day of the week.
        var wDay = d.getDay();
        var yDay = (d - firstDayOfYear) / 86400000;

        if (firstWeekday === 'monday') {
            if (wDay === 0) {
                // Sunday
                wDay = 6;
            } else {
                wDay--;
            }
        }

        return Math.floor((yDay + 7 - wDay) / 7);
    }

    namespace.strftime = strftime;
    namespace.strftimeTZ = strftime.strftimeTZ = strfTimeTZ;
    namespace.strftimeUTC = strftime.strftimeUTC = strftimeUTC;
    namespace.localizedStrftime = strftime.localizedStrftime = localizedStrftime;

}());