Day of next or previous month

Let's find out the day of the week on the first of the previous month. To do this, subtract one from the current month:

javascriptlet now = new Date();

let date = new Date(now.getFullYear(), now.getMonth() - 1, 1);
console.log(date.getDay());

Задание 1

Question: will there be a problem if the current month is January? After all, it has the number 0, and when subtracting one from it, we get minus the first month.

Задание 2

Determine what day of the week was a month ago on the same day of the month as today.