Get the Number of Days in the Current Month in JavaScript

Get the Number of Days in the Current Month #

To get the number of days in the current month:

1. Use the new Date() constructor to get a date object, that corresponds to the last day in the current month.

2. Call the getDate() method to get an integer representing the last day of the month.

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function getDaysInCurrentMonth() {
  const date = new Date();

  return new Date(
    date.getFullYear(),
    date.getMonth() + 1,
    0
  ).getDate();
}

const result = getDaysInCurrentMonth();
console.log(result);

We passed the following 3 parameters to the new Date() constructor:

1. The current year
2. The current month index. Month indexes are zero based - 0 is January and 11 is December. This is why we added 1 to the result.
3. The day for which to create a date object. When 0 is used as the day, we get back the last day of the previous month. We use this approach to balance out the zero-based month index.

It's quite confusing but the getMonth method returns a zero-based index.

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const date = new Date('January 04, 2025 05:24:07');
console.log(date.getMonth()); // 👉️ 0

To balance this out, we pass 0 to the days parameter to get the last day of the prior month.

For example, passing a month index of 2, gives us the last day for February and not March.

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console.log(new Date(2025, 1, 0)); // 👉️ Fri January 31 2025
console.log(new Date(2025, 2, 0)); // 👉️ Fri Feb 28 2025

The last step is to call the Date.getDate method. The method returns an integer from 1 to 31, which represents the day of the month for a given date.

Getting the integer representation of the last day of the current month is the equivalent of getting the number of days in the month.

Further Reading #

• How to get the Current Month in JavaScript
• Get the Number of Days in a Month using JavaScript