startOfWeek function

DateTime startOfWeek(
  1. DateTime date,
  2. int dayStartOfWeek
)

date 所在周的起始日（含 dayStartOfWeek 偏移，0 = 周日）。

Implementation

DateTime startOfWeek(DateTime date, int dayStartOfWeek) {
  final int weekday = date.weekday % 7; // DateTime.weekday: 周一 = 1 … 周日 = 7
  final int diff = (weekday - dayStartOfWeek + 7) % 7;
  return DateTime(date.year, date.month, date.day - diff);
}