strftime.js

/**
 * Formatter
 *
 * date(Object Date, String)
 * http://pubs.opengroup.org/onlinepubs/007908799/xsh/strftime.html
 * + bonus: milliseconds as %SSS
 */


/**
 * Accept source object for converting
 * @param  {Date|String|Number} obj
 * @param  {String}             str
 * @param  {String=}            locale
 * @return {String}
 */
export default function date (obj, str, locale = navigator.language) {
    // Fix time string for some JS engine and convert it to a Date

    if (!obj) {
       obj = new Date();
    }

    /**
     * bad time string format  "2014-08-22T12:06:30+0200" (for iOS with spaces)
     * good time string format "2014-08-19T18:59:21+02:00"
     */
    if (typeof obj === 'string' && /(\-|\+)\d{4}$/.test(obj)) {
        obj = new Date(obj.slice(0, obj.length - 2) + ':' + obj.slice(obj.length - 2));
    }
    /**
     * bad time string format "2014-08-22 12:06:30.0200" (for iOS with spaces)
     * goot time string format "2014-08-22T12:06:30.0200"
     */
    else if (typeof obj === 'string' && / /.test(obj)) {
        obj = new Date(obj.replace(' ', 'T'));
    } else if (!(obj instanceof Date)) {
        obj = new Date(obj);
    }

    /**
     * Convert Date to a String
     * @private
     * @param  {String} str
     * @return {String}
     */
    var _formatDate = function(str) {

        if (typeof str !== 'string') {
            str = String(str);
        }

        return str.replace(/%%|%(SSS|[abcCdDeEHIjmMprRSTxXyYzZ])/g, function(match, code, index, str) {
            if (match === '%%') {
                return '%';
            } else {
                return _formatDate[code](obj);
            }
        });
    };
    /**
     * Pad a number with leading zeros
     * @private
     * @param  {Number} n
     * @param  {String} placer
     * @param  {Number} len
     * @return {String}
     */
    _formatDate._padZero = function(n, placer, len) {
        if (typeof placer === 'undefined') {
            placer = '0';
        }
        if (typeof len === 'undefined') {
            len = 2;
        }
        n = placer + n.toString();
        return n.substr(-len);
    };

    _formatDate.a = function(date) {
        return date.toDateString().split(' ')[0];
    };

    _formatDate.b = function(date) {
        return date.toDateString().split(' ')[1];
    };

    _formatDate.C = function(date) {
        return date.getFullYear().toString().substr(0, 2);
    };

    _formatDate.c = function(date) {
        return date.toLocaleString();
    };

    _formatDate.D = function() {
        return _formatDate('%m/%d/%y');
    };

    _formatDate.d = function(date) {
        return _formatDate._padZero(date.getDate());
    };

    _formatDate.e = function(date) {
        return _formatDate._padZero(date.getMonth() + 1, ' ');
    };

    _formatDate.E = function(date) {
        var sufix,
            value,
            month = date.getMonth() + 1;

        switch (locale) {
            case 'en-US':
                sufix = ['th', 'st', 'nd', 'rd'];
                value = month % 100;
                month += sufix[(value - 20) % 10] || sufix[value] || sufix[0];
                break;
            case 'ru-RU':
                month += '-e';
                break;
            case 'da-DK':
            case 'sv-SE':
                month += ':e';
                break;
            case 'de-DE':
                month += '.';
                break;
            case 'nl-NL':
            case 'fr-FR':
                month += 'e';
                break;
            case 'ro-RO':
                month += 'a';
                break;
            default:
                month += '';
                break;
        }
        return month;
    };

    _formatDate.H = function(date) {
        return _formatDate._padZero(date.getHours());
    };

    _formatDate.I = function(date) {
        return _formatDate._padZero(date.getHours() % 12);
    };

    _formatDate.j = function(date) {
        var day = 0,
            i = 0,
            len = date.getMonth();
        for (; i < len; i++) {
            day += 30;
        }
        return _formatDate._padZero(day + date.getDate(), '0', 3);
    };

    _formatDate.m = function(date) {
        return _formatDate._padZero(date.getMonth() + 1);
    };

    _formatDate.M = function(date) {
        return _formatDate._padZero(date.getMinutes());
    };

    _formatDate.p = function(date) {
        return ['AM', 'PM'][Math.floor(date.getHours() / 12)];
    };

    _formatDate.r = function(date) {
        return _formatDate('%I:%M:%S %p');
    };

    _formatDate.R = function(date) {
        return _formatDate('%H:%M');
    };

    _formatDate.S = function(date) {
        return _formatDate._padZero(date.getSeconds());
    };

    _formatDate.SSS = function(date) {
        return date.getMilliseconds();
    };

    _formatDate.T = function() {
        return _formatDate('%H:%M:%S');
    };

    _formatDate.x = function(date) {
        return date.toLocaleDateString();
    };

    _formatDate.X = function(date) {
        return date.toLocaleTimeString();
    };

    _formatDate.y = function(date) {
        return date.getFullYear().toString().substr(2);
    };

    _formatDate.Y = Date.prototype.getFullYear.bind(obj);

    _formatDate.Z = function(date) {
        var timeZone = date.getTimezoneOffset();

        return (timeZone > 0 ? '+' : '-') + _formatDate._padZero(Math.abs(timeZone), '0', 4);
    };

    if (Object.prototype.toString.call(obj) === '[object Date]') {
        /**
         * Date formatter
         * @param  {String} str
         * @return {String}
         */
        return _formatDate(str);
    }
};