getDayNumberInWeek method
Returns number of the day in week (starting with 1).
Difference from DateTime.weekday is that
you can define first weekday (Monday, Sunday or Saturday) with
parameter firstWeekday
. It should be one of the constant values
DateTime.monday, ..., DateTime.sunday.
By default it's DateTime.monday.
Implementation
int getDayNumberInWeek(DateTime date, {int firstWeekday = DateTime.monday}) {
var res = date.weekday - (firstWeekday) + 1;
if (res <= 0) res += DateTime.daysPerWeek;
return res;
}