How to Get the Number of Days in a Specified Month using JavaScript?

Last Updated : 11 Jul, 2025

Here are different methods to get the number of days in specified month in JavaScript.

1. JavaScript getDate() Method

The getDate() method returns the number of days in a month (from 1 to 31) for the defined date. 

Syntax

Date.getDate();

Example: This example gets the days in the month (February) of the year (2020) by passing the month (1-12) and year to the function daysInMonth. 

JavaScript 
function daysInMonth(month, year) {
    return new Date(year, month, 0).getDate();
}

let date = new Date();
let month = 2;
let year = 2020;
console.log("Number of days in " + month
    + "and month of the year " + year
    + " is " + daysInMonth(month, year));

Output
Number of days in 2and month of the year 2020 is 29

2. Using Array

In this approach, we are using the array to store the month days for each month. We are using the ternary operator to build the logic, on using tat we are returning the number of days according to the month.

JavaScript 
function daysInMonth(month, year) {
    const daysInMonths = [31, (year % 4 === 0 && (year % 100 !== 0 || year % 400 === 0)) 
    ? 29 : 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];
    return daysInMonths[month - 1];
}

let month = 2;
let year = 2024;
console.log("Number of days in " + month + "th month of the year " 
	+ year + " is " + daysInMonth(month, year));

Output
Number of days in 2th month of the year 2024 is 29

3. Using Switch Statement

In this approach, a switch statement is used to return the number of days based on the specified month. This approach is straightforward and allows for direct mapping of month numbers to the corresponding number of days.

JavaScript 
function daysInMonth(month, year) {
    switch (month) {
        case 1: // January
        case 3: // March
        case 5: // May
        case 7: // July
        case 8: // August
        case 10: // October
        case 12: // December
            return 31;
        case 4: // April
        case 6: // June
        case 9: // September
        case 11: // November
            return 30;
        case 2: // February
            return (year % 4 === 0 && (year % 100 !== 0 || year % 400 === 0)) ? 29 : 28;
        default:
            return -1; // Invalid month
    }
}

// Driver code
let month = 2;
let year = 2024;

console.log("Number of days in " + month + "th month of the year " 
	+ year + " is " + daysInMonth(month, year));

Output
Number of days in 2th month of the year 2024 is 29
Comment

Explore