Feature request: Port Moment.js and Moment Timezone to Dart

[matthewlloyd]

The DateTime classes provided by the Dart runtime library are okay but lacking many of the features of e.g. Moment and Moment Timezone. It would be great to have a powerful, world-class library for this, either provided by Flutter itself (to integrate properly with iOS/Android native APIs) or as a package.

https://momentjs.com/

[jonahwilliams]

Does this package accomplish those goals? https://pub.dartlang.org/packages/timezone

[dnfield]

It's not full featured and not moment.js, but I did write a Gregorian calendar package at some point (https://pub.dartlang.org/packages/date_calendar). There's also intl (https://pub.dartlang.org/packages/intl) which can help with formatting and parsing of DateTimes in various locales.

[matthewlloyd]

I took a deep dive into Dart's datetime and timezone libraries, and compared them with Moment and Moment.timezone. This table summarizes what I found. TLDR; Dart has perhaps 2/3 of the features implemented, but they are scattered across various packages, some official, some 3rd party. Most of what I need has already been written (thanks!), but I still think it would be really nice to have one official and comprehensive package. ;)

Feature	Moment.js / Moment.timezone	Dart
locale-aware datetime formatting	yes, 100+ locales	yes, 100+ locales
relative time formatting ("5 minutes ago")	yes, 100+ locales	use timeago package, supports 21 locales
calendar time formatting ("tomorrow at 2pm")	yes, 100+ locales	no
datetime parsing	yes, RFC 2822	yes, RFC 3339
manipulation: add, subtract, durations, etc.	yes	yes
humanized duration formatting ("5 minutes 10 seconds")	yes, 100+ locales	no
timezone database	yes	use timezone package
timezone names, abbreviations, formatting etc.	yes	use timezone package
get user's timezone	yes	use flutter_native_timezone package; full compatibility with timezone package not guaranteed

[stuartmorgan]

Based on the updated guidance in https://github.com/flutter/flutter/wiki/Issue-hygiene#closing-issues, I'm going to close this issue, better reflecting the expectation that this is not something that the Flutter team plans to implement.

[github-actions]

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