이번주 첫째 날, 마지막 날 이번달 첫째 날, 마지막 날 구하기

// 이번 주 첫째날
const getFirtDayOfWeek = date => {
  const currentDate = new Date(date);
  const firstDate = new Date(currentDate.setDate(currentDate.getDate() - currentDate.getDay() + 1)).setHours(0, 0, 0, 0)

  return new Date(firstDate);
}

// 이번 주 마지막째날
const getLastDayOfWeek = date => {
  const currentDate = new Date(date);
  const lastDate = new Date(currentDate.setDate(currentDate.getDate() - currentDate.getDay() + 7)).setHours(23, 59, 59, 0)

  return new Date(lastDate);
}

// 이번 달 첫째 날
const getFirtDayOfMonth = date => {
  const currentDate = new Date(date);
  const firstDate = new Date(currentDate.getFullYear(), currentDate.getMonth(), 1).setHours(0, 0, 0, 0)

  return new Date(firstDate);
}

// 이번 달 마지막째날
const getLastDayOfMonth = date => {
  const currentDate = new Date(date);
  const lastDate = new Date(currentDate.getFullYear(), currentDate.getMonth() + 1, 0).setHours(23, 59, 59, 0)

  return new Date(lastDate);
}