Some methods that should be in this calendar library.

* what's the last day of this month (typically "first of next month - 1")

• today + 1 day
• today + 1 week
• what's the date one week from now
• what's the date N minutes from now (is it still today?)
• when was the last Sunday
• when is the next Saturday?
• When does a week start?

This comment was originally written by @seaneagan

It would be awesome if this library could be on github! I would love to
contribute.

I think a time unit enum would be useful for a lot of these APIs:

enum TimeUnit SECOND, MINUTE, HOUR, DAY, WEEK, MONTH, YEAR;

Example APIs:

DateTime floor(DateTime dt, TimeUnit unit);
DateTime ceil(DateTime dt, TimeUnit unit);
DateTime addTimeUnits(DateTime dt, TimeUnit unit, [int count = 1]);

(of course they could be instance methods on DateTime if TimeUnit were in
dart:core)

Usage:

var now = new DateTime.now();

var startOfDay = floor(now, TimeUnit.DAY); // see issue #10003
var startOfWeek = floor(now, TimeUnit.WEEK);
var endOfMonth = ceil(now, TimeUnit.MONTH);
var inOneDay = addTimeUnits(now, TimeUnit.DAY);
var inOneWeek = addTimeUnits(now, TimeUnit.WEEK);

This comment was originally written by wshadd...@gmail.com

I'd like to also request that a method to return the week # would be great. Possibly just implementing the ISO 8601 standard or giving the option to using Jan 1st as the first week.

Details of the algorithm in javascript can be found at http://techblog.procurios.nl/k/news/view/33796/14863/calculate-iso-8601-week-and-year-in-javascript.html

This comment was originally written by wsh...@gmail.com

I'm just now learning the dart language so here is my first attempt at translating the javascript code to dart. Not optimized and probably buggy, but the couple of spot tests I ran seemed ok.

https://gist.github.com/wshaddix/8797934

I have some needs around this and have started an implementation of a Calendar/GregorianCalendar. https://github.com/dnfield/dart_calendar on pub as date_calendar

Maybe also related to #33014? Functionality similar to Joda Time (in Java) or moment.js (in JavaScript) greatly appreciated :)