Date

`Date.prototype.setFullYear`

Sets the full year for a specified date according to local time and returns the updated timestamp

Syntax

JavaScript

date.setFullYear(yearValue, monthValue?, dateValue?)

Parameters

Parameter	Type	Description
yearValue	number	The full year
monthValue	number	Optional month (0-11)
dateValue	number	Optional day of month (1-31)

Return Value

The number of milliseconds from epoch for the updated date

Examples

Basic Usage

const date = new Date();
date.setFullYear(2025);
console.log(date.getFullYear()); // 2025

Practical Example

const date = new Date('2024-06-15');
date.setFullYear(2024, 0, 1); // Jan 1, 2024
console.log(date.toISOString());

Advanced Usage

function addYears(date: Date, years: number) {
  const d = new Date(date);
  d.setFullYear(d.getFullYear() + years);
  return d;
}

Understanding Date.prototype.setFullYear

The Date.prototype.setFullYear method in JavaScript sets the full year for a specified date according to local time and returns the updated timestamp. It belongs to the Date object and is one of the most widely used methods for working with date values in modern JavaScript and TypeScript applications.

The method signature is date.setFullYear(yearValue, monthValue?, dateValue?). It accepts 3 parameters: yearValue, monthValue, dateValue. When called, it returns the number of milliseconds from epoch for the updated date. Understanding when and how to use setFullYear() helps you write more expressive, readable code.

Common use cases for Date.prototype.setFullYear include data transformation, input validation, API response processing, and building reusable utility functions. It works well alongside related methods like date-getfullyear, date-setmonth, date-setdate, enabling you to chain operations together for complex data manipulation pipelines.

Browser support for Date.prototype.setFullYear is excellent across all modern browsers including Chrome, Firefox, Safari, and Edge. It is also fully supported in Node.js and Deno. For older environments, transpilation with Babel or a polyfill may be needed.