cal.pub0.org/packages/lib/date-fns/index.ts

import dayjs, { Dayjs } from "dayjs";

// converts a date to 2022-04-25 for example.
export const yyyymmdd = (date: Date | Dayjs) =>
  date instanceof Date ? dayjs(date).format("YYYY-MM-DD") : date.format("YYYY-MM-DD");

export const daysInMonth = (date: Date | Dayjs) =>
  date instanceof Date ? dayjs(date).daysInMonth() : date.daysInMonth();