dateformat.js

/*
 * Date Format 1.2.3
 * (c) 2007-2009 Steven Levithan <stevenlevithan.com>
 * MIT license
 *
 * Includes enhancements by Scott Trenda <scott.trenda.net>
 * and Kris Kowal <cixar.com/~kris.kowal/>
 *
 * Accepts a date, a mask, or a date and a mask.
 * Returns a formatted version of the given date.
 * The date defaults to the current date/time.
 * The mask defaults to dateFormat.masks.default.
 */

'use strict';

var dateFormat = (function() {
  var token = /d{1,4}|m{1,4}|yy(?:yy)?|([HhMsTt])\1?|[LloSZWN]|'[^']*'|'[^']*'/g;
  var timezone = /\b(?:[PMCEA][SDP]T|(?:Pacific|Mountain|Central|Eastern|Atlantic) (?:Standard|Daylight|Prevailing) Time|(?:GMT|UTC)(?:[-+]\d{4})?)\b/g;
  var timezoneClip = /[^-+\dA-Z]/g;

  // Regexes and supporting functions are cached through closure
  return function (date, mask, utc, gmt) {

    // You can't provide utc if you skip other args (use the 'UTC:' mask prefix)
    if(arguments.length === 1 && kindOf(date) === 'string' && !/\d/.test(date)) {
      mask = date;
      date = undefined;
    }

    date = date || new Date;

    if(!(date instanceof Date)) {
      date = new Date(date);
    }

    if (isNaN(date)) {
      throw TypeError('Invalid date');
    }

    mask = String(dateFormat.masks[mask] || mask || dateFormat.masks['default']);

    // Allow setting the utc/gmt argument via the mask
    var maskSlice = mask.slice(0, 4);
    if (maskSlice === 'UTC:' || maskSlice === 'GMT:') {
      mask = mask.slice(4);
      utc = true;
      if (maskSlice === 'GMT:') {
        gmt = true;
      }
    }

    var _ = utc ? 'getUTC' : 'get';
    var d = date[_ + 'Date']();
    var D = date[_ + 'Day']();
    var m = date[_ + 'Month']();
    var y = date[_ + 'FullYear']();
    var H = date[_ + 'Hours']();
    var M = date[_ + 'Minutes']();
    var s = date[_ + 'Seconds']();
    var L = date[_ + 'Milliseconds']();
    var o = utc ? 0 : date.getTimezoneOffset();
    var W = getWeek(date);
    var N = getDayOfWeek(date);
    var flags = {
      d:    d,
      dd:   pad(d),
      ddd:  dateFormat.i18n.dayNames[D],
      dddd: dateFormat.i18n.dayNames[D + 7],
      m:    m + 1,
      mm:   pad(m + 1),
      mmm:  dateFormat.i18n.monthNames[m],
      mmmm: dateFormat.i18n.monthNames[m + 12],
      yy:   String(y).slice(2),
      yyyy: y,
      h:    H % 12 || 12,
      hh:   pad(H % 12 || 12),
      H:    H,
      HH:   pad(H),
      M:    M,
      MM:   pad(M),
      s:    s,
      ss:   pad(s),
      l:    pad(L, 3),
      L:    pad(Math.round(L / 10)),
      t:    H < 12 ? 'a'  : 'p',
      tt:   H < 12 ? 'am' : 'pm',
      T:    H < 12 ? 'A'  : 'P',
      TT:   H < 12 ? 'AM' : 'PM',
      Z:    gmt ? 'GMT' : utc ? 'UTC' : (String(date).match(timezone) || ['']).pop().replace(timezoneClip, ''),
      o:    (o > 0 ? '-' : '+') + pad(Math.floor(Math.abs(o) / 60) * 100 + Math.abs(o) % 60, 4),
      S:    ['th', 'st', 'nd', 'rd'][d % 10 > 3 ? 0 : (d % 100 - d % 10 != 10) * d % 10],
      W:    W,
      N:    N
    };

    return mask.replace(token, function (match) {
      if(match in flags) {
        return flags[match];
      }
      return match.slice(1, match.length - 1);
    });
  };
})();

dateFormat.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':             'h:MM TT',
  'mediumTime':            'h:MM:ss TT',
  'longTime':              'h:MM:ss TT Z',
  'isoDate':               'yyyy-mm-dd',
  'isoTime':               'HH:MM:ss',
  'isoDateTime':           'yyyy-mm-dd\'T\'HH:MM:sso',
  'isoUtcDateTime':        'UTC:yyyy-mm-dd\'T\'HH:MM:ss\'Z\'',
  'expiresHeaderFormat':   'ddd, dd mmm yyyy HH:MM:ss Z'
};

// Internationalization strings
dateFormat.i18n = {
  dayNames: [
    'Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat',
    'Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'
  ],
  monthNames: [
    'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec',
    'January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September',
    'October', 'November', 'December'
  ]
};

function pad(val, len) {
  val = String(val);
  len = len || 2;
  while(val.length < len) {
    val = `0${val}`;
  }
  return val;
}

/**
 * Get the ISO 8601 week number
 * Based on comments from
 * http://techblog.procurios.nl/k/n618/news/view/33796/14863/Calculate-ISO-8601-week-and-year-in-javascript.html
 *
 * @param  {Object} `date`
 * @return {Number}
 */
function getWeek(date) {
  // Remove time components of date
  var targetThursday = new Date(date.getFullYear(), date.getMonth(), date.getDate());

  // Change date to Thursday same week
  targetThursday.setDate(targetThursday.getDate() - ((targetThursday.getDay() + 6) % 7) + 3);

  // Take January 4th as it is always in week 1 (see ISO 8601)
  var firstThursday = new Date(targetThursday.getFullYear(), 0, 4);

  // Change date to Thursday same week
  firstThursday.setDate(firstThursday.getDate() - ((firstThursday.getDay() + 6) % 7) + 3);

  // Check if daylight-saving-time-switch occured and correct for it
  var ds = targetThursday.getTimezoneOffset() - firstThursday.getTimezoneOffset();
  targetThursday.setHours(targetThursday.getHours() - ds);

  // Number of weeks between target Thursday and first Thursday
  var weekDiff = (targetThursday - firstThursday) / (86400000*7);
  return 1 + Math.floor(weekDiff);
}

/**
 * Get ISO-8601 numeric representation of the day of the week
 * 1 (for Monday) through 7 (for Sunday)
 *
 * @param  {Object} `date`
 * @return {Number}
 */
function getDayOfWeek(date) {
  var dow = date.getDay();
  if(dow === 0) {
    dow = 7;
  }
  return dow;
}

/**
 * kind-of shortcut
 * @param  {*} val
 * @return {String}
 */
function kindOf(val) {
  if (val === null) {
    return 'null';
  }

  if (val === undefined) {
    return 'undefined';
  }

  if (typeof val !== 'object') {
    return typeof val;
  }

  if (Array.isArray(val)) {
    return 'array';
  }

  return {}.toString.call(val)
    .slice(8, -1).toLowerCase();
};

export default dateFormat;