Function setDay

pkgs/core/src/setDay/index.ts:44–72

(
  date: DateArg<DateType>,
  day: number,
  options?: SetDayOptions<ResultDate>,
)

 * //=> Sun Sep 07 2014 00:00:00
 */
export function setDay<
  DateType extends Date,
  ResultDate extends Date = DateType,
>(
  date: DateArg<DateType>,
  day: number,
  options?: SetDayOptions<ResultDate>,
): ResultDate {
  const defaultOptions = getDefaultOptions();
  const weekStartsOn =
    options?.weekStartsOn ??
    options?.locale?.options?.weekStartsOn ??
    defaultOptions.weekStartsOn ??
    defaultOptions.locale?.options?.weekStartsOn ??
    0;

  const date_ = toDate(date, options?.in);
  const currentDay = date_.getDay();

  const remainder = day % 7;
  const dayIndex = (remainder + 7) % 7;

  const delta = 7 - weekStartsOn;
  const diff =
    day < 0 || day > 6
      ? day - ((currentDay + delta) % 7)
      : ((dayIndex + delta) % 7) - ((currentDay + delta) % 7);
  return addDays(date_, diff, options);
}