date_utility.ts

const getWeekStart = (date: Date=new Date(), mondayStart: boolean=false): Date => {
  const offset = mondayStart ? 1 : 0
  date.setDate(date.getDate() - date.getDay() +offset)
  date.setHours(0,0,0,0)
  return new Date(date)
}

const getWeekEnd = (date: Date=new Date(), mondayStart: boolean=false): Date => {
  const offset = mondayStart ? 1 : 0
  date.setDate(date.getDate() - date.getDay() + 6 + offset)
  date.setHours(23,59,59,59)
  return new Date(date)
}

const getMonthStart = (date: Date=new Date()): Date => {
  date.setDate(1)
  date.setHours(0,0,0,0)
  return new Date(date)
}

const getMonthEnd = (date: Date=new Date()): Date => {
  date.setMonth(date.getMonth()+1)
  date.setDate(0)
  date.setHours(23,59,59,59)
  return new Date(date)
}