Function roundToNearestHours

pkgs/core/src/roundToNearestHours/index.ts:63–92

(
  date: DateArg<DateType>,
  options?: RoundToNearestHoursOptions<ResultDate>,
)

 * //=> Thu Jul 10 2014 08:00:00
 */
export function roundToNearestHours<
  DateType extends Date,
  ResultDate extends Date = DateType,
>(
  date: DateArg<DateType>,
  options?: RoundToNearestHoursOptions<ResultDate>,
): ResultDate {
  const nearestTo = options?.nearestTo ?? 1;

  if (nearestTo < 1 || nearestTo > 12)
    return constructFrom(options?.in || date, NaN);

  const date_ = toDate(date, options?.in);
  const fractionalMinutes = date_.getMinutes() / 60;
  const fractionalSeconds = date_.getSeconds() / 60 / 60;
  const fractionalMilliseconds = date_.getMilliseconds() / 1000 / 60 / 60;
  const hours =
    date_.getHours() +
    fractionalMinutes +
    fractionalSeconds +
    fractionalMilliseconds;

  const method = options?.roundingMethod ?? "round";
  const roundingMethod = getRoundingMethod(method);

  const roundedHours = roundingMethod(hours / nearestTo) * nearestTo;

  date_.setHours(roundedHours, 0, 0, 0);
  return date_;
}