export const diffInDays = (a: Date, b: Date) => {
  const msPerDay = 1000 * 60 * 60 * 24;
  const diff = a.getTime() - b.getTime();
  return Math.round(diff / msPerDay);
};

// Usage
const today = new Date();
const lastWeek = new Date(today.getTime() - 7 * 24 * 60 * 60 * 1000);
diffInDays(today, lastWeek); // 7