Get the First Day of a Year using JavaScript

Get the first day of a Year in JavaScript #

To get the first day of a year, use the Date() constructor to create a date object, passing it a call to the getFullYear() method for the year, 0 for the month, and 1 for the day as parameters. The Date object will contain the first day of the year.

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function getFirstDayOfYear(year) {
  return new Date(year, 0, 1);
}

// 👇️ Current Year
const currentYear = new Date().getFullYear();
// 👇️ Sat Jan 01 2022
console.log(getFirstDayOfYear(currentYear));

// 👇️ Year 2025
console.log(getFirstDayOfYear(2025)); // 👉️ Wed Jan 01 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 0 because we want the first month of the year.

We provided 1 for the day because we want the first day of the year.

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

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function getFirstDayOfYear(year) {
  return new Date(year, 0, 1);
}

// 👇️ Current Year
const currentYear = new Date().getFullYear();
// 👇️ Sat Jan 01 2022
console.log(getFirstDayOfYear(currentYear));

console.log(getFirstDayOfYear(2027)); // 👉️ Fri Jan 01 2027
console.log(getFirstDayOfYear(2030)); // 👉️ Tue Jan 01 2030
console.log(getFirstDayOfYear(2035)); // 👉️ Mon Jan 01 2035

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, you can extract the month in a variable:

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function getFirstDayOfYear(year) {
  const january = 0;
  return new Date(year, january, 1);
}

Further Reading #

• Get the Last Day of the Year in JavaScript
• Get the Last Day of Next Month in JavaScript