Get the Last Day of the Year in JavaScript

Get the Last Day of the Year #

To get the last day of the year, use the Date() constructor to create a date object, passing it a call to the getFullYear() method for the year, 11 for the month, and 31 for the day as parameters. The Date object will contain the last day of the year.

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function getLastDayOfYear(year) {
  return new Date(year, 11, 31);
}

// 👇️ Current Year
const currentYear = new Date().getFullYear();
console.log(getLastDayOfYear(currentYear)); // 👉️ Sat Dec 31 2022

// 👇️ Year 2025
console.log(getLastDayOfYear(2025)); // 👉️ Wed Dec 31 2025

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

1. The year
2. The month
3. The day

We used the Date.getFullYear method to get the current year.

For the month, we hard coded 11 because we want the last month of the year.

The getLastDayOfYear function works for any year, here are some examples.

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function getLastDayOfYear(year) {
  return new Date(year, 11, 31);
}

// 👇️ Current Year
const currentYear = new Date().getFullYear();
console.log(getLastDayOfYear(currentYear)); // 👉️ Sat Dec 31 2022

console.log(getLastDayOfYear(2030)); // 👉️ Tue Dec 31 2030
console.log(getLastDayOfYear(2035)); // 👉️ Mon Dec 31 2035
console.log(getLastDayOfYear(2040)); // 👉️ Mon Dec 31 2040

The only tricky thing here is to remember that months are zero-based and go from 0 (January) to 11 (December).

If you want to make the function easier to read and more intuitive, you can extract the digit 11 in a variable, like so.

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function getLastDayOfYear(year) {
  const december = 11;
  return new Date(year, december, 31);
}

Further Reading #

• Get the First Day of a Month in JavaScript
• How to get the First Day of the Year in JavaScript