moment_dart 0.10.3

Immutable DateTime subclass for easier interaction with DateTime objects. Supports multiple localizations to convert DateTime into human-readable format

Inspired by moment.js

Features

Convert DateTime to human-readable text ✅

• Relative duration
• Calendar text
• Formatted dates
• Multiple localizations

Play with DateTime objects 😎

• Start of year/month/.../millis
• Find last or next weekday
• Is same year/month/.../moment as

Handful of other useful extension/functions

Demo 👁️

🔗 A Flutter web demo

Getting started ✨

Import the package

import 'package:moment_dart/moment_dart.dart';

Create Moment instance

final now = Moment.now();

final epoch = Moment.fromMillisecondsSinceEpoch(0, isUtc: true);

/// Using extension (DateTime.toMoment())
final bday = DateTime(2003, 6, 1, 5, 1).toMoment();
/// or from [DateTime]
final bday = Moment(DateTime(2003, 6, 1, 5, 1));

Please note that Moment is subclass of DateTime. (It is immutable, like its superclass)

final now = Moment.now();

assert(now is DateTime); // true
assert(now is Moment); // true

Usage 🌿

Relative durations

final Moment yesterday = Moment.now() - Duration(days: 1);

yesterday.fromNow(); // a day ago

// You can omit prefix/suffix
yesterday.fromNow(true); // a day

yesterday.from(yesterday - Duration(days: 365)); // a year ago

Calendar dates

now.subtract(const Duration(days: 1)).calendar(); // Yesterday at 10:02AM
now.calendar();                                   // Today at 10:02AM
now.subtract(const Duration(days: 1)).calendar(); // Tomorrow at 10:02AM

// [reference] - defaults to Moment.now(), acts as an anchor.
// [omitHours] - omits the hour part. Hour part is formatted by "LT" token.
now.calendar(
  reference: (now - const Duration(days: 1)),
  omitHours: true,
); // Tomorrow

Start of year/month/.../moment

final Moment tada =
      DateTime(2022, 6, 19, 21, 9, 33).toMoment(); // June 19 2022 09:09 PM

tada.startOf(DurationUnit.day); // June 19 2022 12:00 AM
// OR
tada.startOfDay(); // June 19 2022 12:00 AM

Find last/next weekday

Works on DateTime and Moment

We're always dealing with local date times here. If the date is UTC, it's converted to local beforehand.

final Moment tada =
      DateTime(2022, 6, 19, 21, 9, 33).toMoment(); // June 19 2022 09:09 PM

tada.nextMonday(); // June 20 2022 09:09 PM

tada.lastMonday(); // June 13 2022 09:09 PM

Note that this Sunday is neither last or next Sunday

tada.lastSunday(); // June 12 2022 09:09 PM

Is same unit as

Works on DateTime and Moment

final DateTime otherBday = DateTime(2003,6,19);
final Moment spiritRoverOnMars = DateTime(2003,6,10).toMoment();

otherBday.isAtSameMonthAs(spiritRoverOnMars); // true
otherBday.isAtSameYearAs(spiritRoverOnMars); // true

⚠️ It takes timezones into account

final DateTime bday = DateTime(2003,6,1,5,33); // 2003-05-31 21:33:00.000Z (Local time zone was GMT+08:00)
final Moment spiritRoverOnMars = DateTime(2003,6,10).toMoment(); // 2003-06-09 16:00:00.000Z

bday.isAtSameMonthAs(spiritRoverOnMars); // false; didn't happen in same month. Bday was in May, Spirit Rover landed in June.
bday.isAtSameYearAs(spiritRoverOnMars); // true

Formatting

See list of format tokens

now.format("YYYY MMMM Do - hh:mm:ssa");   //2003 June 1st - 05:01:00am
now.format("LTS", true);                  //5:01:00 AM (Converted to Local first)
now.format("dddd");                       //Sunday
DateTime.now().format("MMM Do YY", true); //Jun 1st 03 (Converted to Local first)

Escape strings by encasulating them in square brackets ([]).

epoch.format("YYYY [YYYY] MMMM [MMMM] Do [Do] LT [A]"); // 1970 YYYY January MMMM 1st Do 12:00 AM A

Alternatively, unmatched tokens will be left as is

epoch.format("YYYY년 MMM D일 ddd A h:mm"); // 1970년 1월 1일 목 오전 8:00 (Localization: KO)

There are functions for few commonly used formatters

// Shorthands

moment.formatDate(); // LL
moment.formatDateShort(); // ll
moment.formatDateTime(); // LLL
moment.formatDateTimeShort(); // lll
moment.formatDateTimeWithWeekday(); // LLLL
moment.formatDateTimeWithWeekdayShort(); // llll
moment.formatTime(); // LT
moment.formatTimeWithSeconds(); //LTS 

// OR formatter token as getter

moment.LL;
moment.ll;
moment.LLL;
moment.lll;
moment.LLLL;
moment.llll;
moment.LT;
moment.LTS;

Parsing

Currently uses DateTime.parse()

COMING SOON 💫

Changing localization 🌐

Localization defaults to MomentLocalizations.enUS()

final Moment hangulday2022 = Moment(DateTime(2022,10,9), localization: MomentLocalizations.ko());

hangulday2022.format("ll"); // 2022년 10월 9일
hangulday2022.LL; // 2022년 10월 9일 (same as Moment.format("LL"))
hangulday2022.formatTime(); // 오전 12:00 (same as Moment.format("LT"))

Available Localization classes:

Localizations are classes that extend MomentLocalization

See how you can create your own localization

Class	LCID	Language	Country
LocalizationEnUs	EnUs	English	United States
LocalizationKoKr	KoKr	Korean	South Korea
LocalizationFrFr	FrFr	French	France
LocalizationEsEs	EsEs	Spanish	Spain
LocalizationItIt	ItIt	Italian	Italy
LocalizationDeDe	DeDe	German	Germany
LocalizationMnMn	MnMn	Mongolian	Mongolia
LocalizationMnMongMn	MnMongMn	Traditional Mongolian	Mongolia
LocalizationMnQaaqMn	MnQaaqMn	Traditional Mongolian with Traditional Numbers	Mongolia

Batteries included 🔋

Moment provides an extension with set of useful functions. Can be called on either Moment or DateTime instance

final Moment date = DateTime(2022,03,29).toMoment();
// It can also work on [DateTime] too!
final DateTime date = DateTime(2022,03,29);

//Returns the ISO Week number of the year
//
// [1,2,3,...,52,53]
date.week == 13; // true

// Returns the year according to ISO Week
date.weekYear == 2022; // true

// Returns the quarter of the year. [][Jan,Feb,Mar][Apr,May,Jun][Jul,Aug,Sep][Oct,Nov,Dec]
//
// [1,2,3,4]
date.quarter == 1; // true

// Returns if the [year] is leap year
date.isLeapYear == false; // true

/// Returns ordinal day of the year
/// 
/// [1,2,3,...,365,366]
date.dayOfYear == 88; // true

Comparison can be called on either Moment or DateTime. Accounts UTC/Local timezone.

Available for all units: year, month, day, hour, minute, second, millisecond, microsecond

final DateTime local = DateTime(1972, 1, 1, 7); // Jan 1, 1972 at 7AM @GMT+8
final DateTime utc = local.toUtc();             // Dec 31, 1971 at 11PM @UTC

local.isAtSameYearAs(utc); // true;

Read more about ISO week on Wikipedia

Creating your own Localization ➕

Extend MomentLocalization class to get started.

Almost everything is declared as function, so you can freely achieve the unique features of your language.

I highly recommend copying one of the existing implementations then work on top of it!

import 'package:moment_dart/src/formatters/token.dart';
import 'package:moment_dart/src/calendar.dart';
import 'package:moment_dart/src/localizations.dart';

class LocalizationEnMeowKC extends MomentLocalization {
  @override
  CalenderLocalizationData get calendarData => CalenderLocalizationData(
        keywords: CalenderLocalizationKeywords(
          at: (date, time) => "meow $time",
          lastWeekday: (weekday) => "Last meow $weekday",
          nextWeekday: (weekday) => weekday,
        ),
        relativeDayNames: {
          -1: "Yestermeow",
          0: "Meowday",
          1: "Tomeowow",
        },
      );

  @override
  String? get countryCode => "KC"; // Kingdom of Cats

  @override
  String get endonym => "Meow!";

  @override
  String get languageCode => "en";

  @override
  String get languageNameInEnglish => "Meowlish!";

  @override
  String get locale => "en_Meow_KC"; // You may want to override this one

  @override
  Map<FormatterToken, FormatterTokenFn?> overrideFormatters() => {
        // Localization aware formats - Highly recommend implementing these :)
        FormatterToken.L: (dateTime) => reformat(dateTime, "YYYY/MM/DD"),
        FormatterToken.l: (dateTime) => reformat(dateTime, "YYYY/M/D"),
        FormatterToken.LL: (dateTime) =>
            reformat(dateTime, "MMMM D, [meow] YYYY"),
        FormatterToken.ll: (dateTime) =>
            reformat(dateTime, "MMM D, [meow] YYYY"),
        FormatterToken.LLL: (dateTime) =>
            reformat(dateTime, "MMMM D, [meow] YYYY, HH:mm [meow!]"),
        FormatterToken.lll: (dateTime) =>
            reformat(dateTime, "MMM D, [meow] YYYY, HH:mm [meow!]"),
        FormatterToken.LLLL: (dateTime) =>
            reformat(dateTime, "dddd, MMMM D, [meow] YYYY, HH:mm [meow!]"),
        FormatterToken.llll: (dateTime) =>
            reformat(dateTime, "ddd, MMM D, [meow] YYYY, HH:mm [meow!]"),
        FormatterToken.LT: (dateTime) => reformat(dateTime, "HH:mm"),
        FormatterToken.LTS: (dateTime) => reformat(dateTime, "HH:mm:ss"),
      };

  @override
  String relative(Duration duration, [bool dropPrefixOrSuffix = false]) =>
      "(in) Meow $duration (ago)";

  @override
  Map<int, String> get weekdayName => {
        DateTime.monday: "Meowday #1",
        ...,
        DateTime.sunday: "Meowday #7",
      };
}

You may want to use mixins to make your experience easier. Take a look at other localization implementations, but I'll provide an example anyways:

class MewLocale extends MomentLocalization with Ordinal, MonthNames {
  /* ... folded code ... */

  @override
  Map<int, String> get monthNames => {
    DateTime.january: "Janmeow",
    ...,
    DateTime.december: "Decemeow",
  };

  @override
  Map<int, String> get monthNamesShort => monthNames.map((key, value) => MapEntry(key, value.substring(0,3)));

  @override
  String ordinalNumber(int n) => "meow $nº";

  @override
  Map<FormatterToken, FormatterTokenFn?> overrideFormatters() => {
        // From [EnglishLikeOrdinal] mixin
        ...formattersWithOrdinal, // Provided by mixin `Ordinal`
        // From [MonthNames] mixin
        ...formattersForMonthNames, // Provided by mixin MonthNames
        
        /* Other formatters */
      };
}

Format Tokens 🔑

Encapsulate string in square brackets ([]) to escape.

Type	Token	Examples	Description
Month	M	1 2 ... 11 12
	Mo	1st 2nd ... 11th 12th
	MM	01 02 ... 11 12
	MMM	Jan Feb ... Nov Dec
	MMMM	January February ... November December
Quarter of year	Q	1 2 3 4
	Qo	1st 2nd 3rd 4th
Day of month	D	1 2 ... 30 31
	Do	1st 2nd ... 30th 31st
	DD	01 02 ... 30 31
Day of year	DDD	1 2 ... 364 365
	DDDo	1st 2nd ... 364th 365th
	DDDD	001 002 ... 364 365
Day of week	d	1 2 ...6 7	Moment.js uses `0-6`. However, we'll be using `1-7` to be in accordance with [DateTime]
	d_o	1st 2nd ... 6th 7th	"do" is Dart language keyword
	dd	Mo Tu ... Sa Su
	ddd	Mon Tue ... Sat Sun
	dddd	Monday ... Saturday Sunday
Day of week (ISO)	e	1 2 ... 6 7
Week of year (ISO)	w	1 2 ... 52 53
	wo	1st 2nd ... 52nd 53rd
	ww	01 02 ... 52 53
Year	YY	70 71 ... 29 30
	YYYY	1970 1971 ... 2029 2030
Era Year	y	1 2 ... 2020 ...
Era	NN	BC AD	Abbr era name
	NNNN	Before Christ, Anno Domini	Full era name
	NNNNN	BC AD	Narrow era name
Week year	gg	70 71 ... 29 30
	gggg	1970 1971 ... 2029 2030
AM/PM	A	AM PM	UPPERCASE
	a	am pm	lowercase
Hour	H	0 1 ... 22 23
	HH	00 01 ... 22 23
	h	1 2 ... 11 12
	hh	01 02 ... 11 12
	k	1 2 ... 23 24
	kk	01 02 ... 23 24
Minute	m	0 1 ... 58 59
	mm	00 01 ... 58 59
Second	s	0 1 ... 58 59
	ss	00 01 ... 58 59
Fractional second	S	0 1 ... 8 9
	SS	00 01 ... 98 99
	SSS	000 001 ... 998 999
	SSSS	0000 0001 ... 9998,9999
	SSSSS	00000 00001 ... 99998,99999
	SSSSSS	000000 000001 ... 999998,999999
Timezone	Z	-07:00 -06:00 ... +06:00 +07:00
	ZZ	-0700 -0600 ... +0600 +0700
Timezone name	ZZZ		Returns [DateTime.timeZoneName], result may not be consistent across platforms
Unix timestamp in seconds	X	1654063960
Unix timestamp	x	1654063974620
Localization Defaults	l	9/4/1986	Date (in local format, shorter)
	L	09/04/1986	Date (in local format)
	ll	Sep 4 1986	Month name, day of month, year (shorter)
	LL	September 04 1986	Month name, day of month, year
	lll	Sep 4 1986 8:30 PM	Month name, day of month, year, time
	LLL	September 04 1986 8:30 PM	Month name, day of month, year, time
	llll	Thu, Sep 4 1986 8:30 PM	Day of week, month name, day of month, year, time (shorter)
	LLLL	Thursday, September 04 1986 8:30 PM	Day of week, month name, day of month, year, time
	LT	8:30 PM	Time (without seconds)
	LTS	8:30:00 PM	Time (with seconds)

TODO ✔️

• Add more localizations
• Implement parsing