When you use now.setDate(-1), you're not actually rolling back the date to the previous month. Instead, you're setting the date to the 1st day of the current month minus 1 day.

Here's how it works:

1.Initial Date: Let's say today is October 23, 2024. 2.Setting the Date: When you call now.setDate(-1), you're telling it to set the date to the 1st of October (because the Date object rolls back to the start of the month) and then subtract 1 day, which results in September 29, 2024.

Use this to get the

const now = new Date();
const lastDayOfPreviousMonth = new Date(now.getFullYear(), now.getMonth(), 0);

console.log(`Last Day of Previous Month: ${lastDayOfPreviousMonth}`);

Explanation:

• new Date(year, monthIndex, day): This constructor creates a new date.
• The monthIndex is zero-based (0 for January, 1 for February, etc.).
• now.getFullYear(): Gets the current year. now.getMonth() - 1: Gets he previous month.