What is setFullYear() in JavaScript?

The setFullYear function in JavaScript is a method of the Date class with the following syntax:

setFullYear(yearValue)
setFullYear(yearValue, monthValue)
setFullYear(yearValue, monthValue, dateValue)

Parameters

yearValue is an integer that denotes the year.
monthValue is an integer in the range 0 to 11, where 0 represents January and 11 represents December.
dateValue is an integer in the range 1 to 31 which denotes the date of the current month. The monthValue must also be specified if the dateValue is used.

Note: Only the yearValue parameter is required, the rest are optional.

Return value

setFullYear() returns the number of milliseconds elapsed since 1 January 1970 00:00:00 UTC till the updated time.

The setFullYear function is called on a Date object, which results in the specified parameters being changed in the Date object.

Example

The following code demonstrates the usage of the setFullYear function:

let d1 = new Date('June 29, 2021 15:39:05:32');
let d2 = new Date('June 29, 2021 15:39:05:32');
let d3 = new Date('June 29, 2021 15:39:05:32');
console.log('Dates Before Changing:');
console.log('d1: ', d1);
console.log('d2: ', d2);
console.log('d3: ', d3);
console.log('Return Values:');
console.log(d1.setFullYear(2008));
console.log(d2.setFullYear(2008, 8));
console.log(d3.setFullYear(2008, 8, 8));
console.log('Dates After Changing:');
console.log('d1: ', d1);
console.log('d2: ', d2);
console.log('d3: ', d3);

In the example above, the variables d1, d2, and d3 are Date objects that initially have the same date, June 29, 2021 15:39:05:32. The setFullYear function is applied to all of the variables, with varying parameters. For d1, only the year is set to 2008. For d2, both year and month are set to 2008 and September respectively. And for d3, year, month, and date are set to 2008, September, and 8 respectively.

The example above also shows the return value from the function calls after Return Values: is printed onto the standard output.

Free Resources