CODEWITHSUNDEEP
javascript
Sam
Sam

Reputation: 30342

Number of days in a month giving strange results

I've created the following function that should return the number of days in a month but I'm not getting expected results.

export const getNumberOfDaysInMonth = (year, month) => {

    const myDate = new Date(year, month - 1, 0);
    return myDate.getDate();
}

I'm passing year = 2017 and month = 6. As you'll see I'm subtracting 1 from month because as I understand it, JS uses a 0 based numbering system for months.

This sets myDate to May 31, 2017 and the function returns 31 days.

If I change the formula to const myDate = new Date(year, month - 1, 1);, it does set the date to June 1, 2017 and returns 1 day as the number of days.

I can use a switch statement to return the number of days in a month but that seems cumbersome and it wouldn't even take into account leap years, etc. Is there an elegant way to get the total number of days in a particular month in a particular year?

For example, if I pass year = 2016 and month = 2, I should get 29 not 28.

Upvotes: 1

Views: 65

Answers (1)

Aakash Sigdel
Aakash Sigdel

Reputation: 9310

When doing

const myDate = new Date(year, month - 1, 0);

you don't need to subtract 1 from the month. This is because the third parameter in the date function here, represents the day of the month, is set to 0 which actually means last day of the previous month. So just doing this

const myDate = new Date(year, month, 0);

should give you the desired result of number of days in a month.

Upvotes: 1

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