strftime.js

;(function () {
  var strftime = function (fmt, d) {
    if (!(d instanceof Date)) {
      var _d = new Date();
      if (!isNaN(d)) {
        _d.setTime(d * 1000); /* epoch s -> ms */
      }
      d = _d;
    }
    if (typeof(d) === 'undefined') {
      return "";
    }

    en_US = {
      pref: {
        /* %c */ datetime: function (d) { return strftime("%a %b %e %H:%M:%S %Y", d); },
        /* %x */ date:     function (d) { return strftime("%m/%d/%Y", d); },
        /* %X */ time:     function (d) { return strftime("%H:%M:%S", d); }
      },
      weekday: {
        abbr: ['Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat'],
        full: ['Sunday',
               'Monday',
               'Tuesday',
               'Wednesday',
               'Thursday',
               'Friday',
               'Saturday']
      },
      month: {
        abbr: ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun',
               'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'],
        full: ['January',
               'February',
               'March',
               'April',
               'May',
               'June',
               'July',
               'August',
               'September',
               'October',
               'November',
               'December']
      },
      AM: "AM", am: "am", PM: "PM", pm: "pm",
      ordinal: ['th', 'st', 'nd', 'rd', 'th', 'th', 'th', 'th', 'th', 'th', 'th', //  1 - 10
                      'th', 'th', 'th', 'th', 'th', 'th', 'th', 'th', 'th', 'th', // 11 - 20
                      'st', 'nd', 'rd', 'th', 'th', 'th', 'th', 'th', 'th', 'th', // 21 - 30
                      'st'],
      zero:  ['00', '01', '02', '03', '04', '05', '06', '07', '08', '09',
              '10', '11', '12', '13', '14', '15', '16', '17', '18', '19',
              '20', '21', '22', '23', '24', '25', '26', '27', '28', '29',
              '30', '31', '32', '33', '34', '35', '36', '37', '38', '39',
              '40', '41', '42', '43', '44', '45', '46', '47', '48', '49',
              '50', '51', '52', '53', '54', '55', '56', '57', '58', '59'],

      space: [' 0', ' 1', ' 2', ' 3', ' 4', ' 5', ' 6', ' 7', ' 8', ' 9',
              '10', '11', '12', '13', '14', '15', '16', '17', '18', '19',
              '20', '21', '22', '23', '24', '25', '26', '27', '28', '29',
              '30', '31', '32', '33', '34', '35', '36', '37', '38', '39',
              '40', '41', '42', '43', '44', '45', '46', '47', '48', '49',
              '50', '51', '52', '53', '54', '55', '56', '57', '58', '59'],
    };

    var lc = en_US;

    var inspec = false;
    var alt_o  = false;

    var s = '';
    for (var i = 0; i < fmt.length; i++) {
      var c = fmt.charCodeAt(i);
      if (inspec) {
        switch (c) {
        // %%   A literal '%' character
        case 37:
          s += '%';
          break;

        // %a   The abbreviated name of the day of the week according to the
        //      current locale.
        case 97:
          s += lc.weekday.abbr[d.getDay()];
          break;

        // %A   The full name of the day of the week according to the current
        //      locale.
        case 65:
          s += lc.weekday.full[d.getDay()];
          break;

        // %b   The abbreviated month name according to the current locale.
        case 98:
          s += lc.month.abbr[d.getMonth()];
          break;

        // %h   Equivalent to %b.
        case 104:
          s += lc.month.abbr[d.getMonth()];
          break;

        // %B   The full month name according to the current locale.
        case 66:
          s += lc.month.full[d.getMonth()];
          break;

        // %c   The preferred date and time representation for the current
        //      locale.
        case 99:
          s += lc.pref.datetime(d);
          break;

        // %C   The century number (year/100) as a 2-digit integer
        case 67:
          s += parseInt(d.getFullYear() / 100);
          break;

        // %d   The day of the month as a decimal number (range 01 to 31).
        case 100:
          s += lc.zero[d.getDate()];
          break;

        // %D   Equivalent to %m/%d/%y.  (Yecch—for Americans only.  Americans
        //      should note that in other countries %d/%m/%y is rather common.
        //      This means that in international context this format is
        //      ambiguous and should not be used.)
        case 68:
          s += strftime("%m/%d/%y", d);
          break;

        // %e   Like %d, the day of the month as a decimal number, but a
        //      leading zero is replaced by a space.
        case 101:
          s += d.getDate().toString()+(alt_o ? lc.ordinal[d.getDate()] : '');
          break;

        // %E   Modifier: use alternative format, see below.
        case 69:
          // not supported; just skip it
          continue;

        // %F   Equivalent to %Y-%m-%d (the ISO 8601 date format).
        case 70:
          s += strftime("%Y-%m-%d", d);
          break;

        // %G   The ISO 8601 week-based year (see NOTES) with century as a
        //      decimal number.  The 4-digit year corresponding to the ISO
        //      week number (see %V).  This has the same format and value as
        //      %Y, except that if the ISO week number belongs to the previous
        //      or next year, that year is used instead.
        case 71:
          throw "this strftime() does not support '%G'";

        // %g   Like %G, but without century, that is, with a 2-digit year
        //      (00-99).
        case 103:
          throw "this strftime() does not support '%g'";

        // %H   The hour as a decimal number using a 24-hour clock (range 00 to 23).
        case 72:
          s += lc.zero[d.getHours()]
          break;

        // %I   The hour as a decimal number using a 12-hour clock (range 01 to 12)
        case 73:
          s += lc.zero[d.getHours() % 12 == 0 ? 12 : d.getHours() % 12];
          break;

        // %j   The day of the year as a decimal number (range 001 to 366).
        case 106:
          throw "this strftime() does not support '%j'";

        // %k   The hour (24-hour clock) as a decimal number (range 0 to 23);
        //      single digits are preceded by a blank.  (See also %H.)
        case 107:
          s += lc.space[d.getHours()];
          break;

        // %l   The hour (12-hour clock) as a decimal number (range 1 to 12);
        //      single digits are preceded by a blank.  (See also %I.)
        case 108:
          s += lc.space[d.getHours() % 12 == 0 ? 12 : d.getHours() % 12];
          break;

        // %m   The month as a decimal number (range 01 to 12).
        case 109:
          s += lc.zero[d.getMonth()+1];
          break;

        // %M   The minute as a decimal number (range 00 to 59).
        case 77:
          s += lc.zero[d.getMinutes()];
          break;

        // %n   A newline character.
        case 110:
          s += "\n";
          break;

        // %O   Modifier: use alternative format, see below.
        case 79:
          alt_o = true;
          continue;

        // %p   Either "AM" or "PM" according to the given time value, or the
        //      corresponding strings for the current locale.  Noon is treated
        //      as "PM" and midnight as "AM".
        case 112:
          s += (d.getHours() < 12 ? lc.AM : lc.PM);
          break;

        // %P   Like %p but in lowercase: "am" or "pm" or a corresponding
        //      string for the current locale.
        case 80:
          s += (d.getHours() < 12 ? lc.am : lc.pm);
          break;

        // %r   The time in a.m. or p.m. notation.  In the POSIX locale this
        //      is equivalent to %I:%M:%S %p.
        case 114:
          s += lc.zero[d.getHours() % 12 == 0 ? 12 : d.getHours() % 12] + ":" +
               lc.zero[d.getMinutes()]                                  + ":" +
               lc.zero[d.getSeconds()]                                  + " " +
               (d.getHours() < 12 ? lc.AM : lc.PM);
          break;

        // %R   The time in 24-hour notation (%H:%M).  For a version
        //      including the seconds, see %T below.
        case 82:
          s += lc.zero[d.getHours()] + ":" +
               lc.zero[d.getMinutes()];
          break;

        // %s   The number of seconds since the Epoch,
        //      1970-01-01 00:00:00+0000 (UTC).
        case 115:
          s += d.getTime().toString();
          break;

        // %S   The second as a decimal number (range 00 to 60).  (The range
        //      is up to 60 to allow for occasional leap seconds.)
        case 83:
          s += lc.zero[d.getSeconds()];
          break;

        // %t   A tab character.
        case 116:
          s += "\t";
          break;

        // %T   The time in 24-hour notation (%H:%M:%S).
        case 84:
          s += lc.zero[d.getHours()]   + ":" +
               lc.zero[d.getMinutes()] + ":" +
               lc.zero[d.getSeconds()];
          break;

        // %u   The day of the week as a decimal, range 1 to 7, Monday being 1.
        //       See also %w.
        case 117:
          var wday = d.getDay();
          if (wday == 0) { wday = 7 };
          s += (wday).toString()+(alt_o ? lc.ordinal[wday] : '');
          break;

        // %U   The week number of the current year as a decimal number, range
        //      00 to 53, starting with the first Sunday as the first day of
        //      week 01.  See also %V and %W.
        case 85:
          throw "this strftime() does not support '%U'";

        // %V   The ISO 8601 week number (see NOTES) of the current year as a
        //      decimal number, range 01 to 53, where week 1 is the first week
        //      that has at least 4 days in the new year.  See also %U and %W.
        case 86:
          throw "this strftime() does not support '%V'";

        // %w   The day of the week as a decimal, range 0 to 6, Sunday being 0
        //      See also %u.
        case 119:
          s += (d.getDay()).toString();
          break;

        // %W   The week number of the current year as a decimal number, range
        //      00 to 53, starting with the first Monday as the first day of
        //      week 01.
        case 87:
          throw "this strftime() does not support '%W'";

        // %x   The preferred date representation for the current locale
        //      without the time.
        case 120:
          s += lc.pref.date(d);
          break;

        // %X   The preferred time representation for the current locale
        //      without the date.
        case 88:
          s += lc.pref.time(d);
          break;

        // %y   The year as a decimal number without a century (range 00 to 99).
        case 121:
          s += lc.zero[d.getFullYear() % 100];
          break;

        // %Y   The year as a decimal number including the century.
        case 89:
          s += d.getFullYear();
          break;

        // %z   The +hhmm or -hhmm numeric timezone (that is, the hour and
        //      minute offset from UTC).
        case 122:
          throw "this strftime() does not support '%z'";

        // %Z   The timezone name or abbreviation.
        case 90:
          throw "this strftime() does not support '%Z'";

        default:
          throw "unrecognized strftime sequence '%"+fmt[i]+"'";
        }

        inspec = false;
        alt_o  = false;
        continue;
      }

      if (c == 37) { // %
        inspec = true
        continue;
      }

      s += fmt[i];
    }
    return s;
  };

  Lens.strftime = strftime;
  window.strftime = strftime;
})();