const getDaysInMonth = (year, month) => new Date(year, month, 0).getDate()

const addMonths = (input, months) => {
  const date = new Date(input)
  date.setDate(1)
  date.setMonth(date.getMonth() + months)
  date.setDate(Math.min(input.getDate(), getDaysInMonth(date.getFullYear(), date.getMonth()+1)))
  return date
}