previousDayOfTheWeek function

DateTime previousDayOfTheWeek(
  1. DateTime from,
  2. int weekday
)

Return a new instance DateTime with previous day of the week

from DateTime that will have incremented days weekday use 1 for Sunday .. 7 for Saturday

Implementation

DateTime previousDayOfTheWeek(DateTime from, int weekday) {
  assert(weekday <= 7, 'weekday:$weekday must be less or equal then 7');
  assert(weekday > 0, 'weekday:$weekday must be grater then 0');
  var result = from.copyWith();
  while (result.weekday != weekday) {
    result = result.add(Duration(days: -1));
  }
  return result;
}