Fix timezone offset

constructor.ts

const fn = (string: string /* yyyy-mm-dd */): Date => {
  const [year, month, day] = string.split('-').map(Number);
  const date = new Date(year, month - 1, day);
  return date;
};

impure.ts

const fn = (date: Date): Date => {
  date.setMinutes(date.getMinutes() + date.getTimezoneOffset());
  return date;
};

pure.ts

const fn = (date: Date): Date => {
  const copy = new Date(date)
  copy.setMinutes(copy.getMinutes() + copy.getTimezoneOffset());
  return copy;
};