Function floorTime

src/ui-react-dom-charts/common/wilkinson.ts:317–333

(timestamp: number, [unit, step]: TimeInterval)

};

const floorTime = (timestamp: number, [unit, step]: TimeInterval): number => {
  const date = dateNew(timestamp);
  const year = dateGetUTCFullYear(date);
  const month = dateGetUTCMonth(date);
  const monthStep = unit == QUARTER_UNIT ? step * 3 : step;
  const monthIndex = year * 12 + month;
  const flooredMonthIndex = mathFloor(monthIndex / monthStep) * monthStep;
  const fixedInterval = getFixedInterval(unit, step);
  return unit == YEAR_UNIT
    ? dateUtc(mathFloor(year / step) * step, 0, 1)
    : unit == QUARTER_UNIT || unit == MONTH_UNIT
      ? dateUtc(mathFloor(flooredMonthIndex / 12), flooredMonthIndex % 12, 1)
      : unit == WEEK_UNIT
        ? dateUtc(year, month, dateGetUTCDate(date)) -
          ((dateGetUTCDay(date) + 6) % 7) * DAY
        : mathFloor(timestamp / fixedInterval) * fixedInterval;
};

const addTime = (timestamp: number, [unit, step]: TimeInterval): number => {
  const date = dateNew(timestamp);