Number of days in a month

1  // 'month' is starting from 0
2  // daysInMonth(2022, 1) -> 28
3  const daysInMonth = (year, month) => {
4    const dayInMs = 1000 * 60 * 60 * 24;
5    const nextMonthFirstDay = new Date(year, month + 1, 1);
6  
7    return new Date(nextMonthFirstDay - dayInMs).getDate();
8  };