The setYear() method of Date instances sets the year for a specified date according to local time.
However, the way the legacy setYear() method sets year values is different from how the preferred setFullYear() method sets year values — and in some cases, also different from how new Date() and Date.parse set year values. Specifically, given two-digit numbers, such as 22 and 61:
setYear()interprets any two-digit number as an offset to1900; sodate.setYear(22)results in the year value being set to1922, anddate.setYear(61)results in the year value being set to1961. (In contrast, whilenew Date(61, 1)also results in the year value being set to1961,new Date("2/1/22")results in the year value being set to2022; and similarly for Date.parse).setFullYear() does no special interpretation but instead uses the literal two-digit value as-is to set the year; so
date.setFullYear(61)results in the year value being set to0061, anddate.setFullYear(22)results in the year value being set to0022.
Because of those differences in behavior, you should no longer use the legacy setYear() method, but should instead use the preferred setFullYear() method.
Syntax
setYear(yearValue)
Parameters
yearValue- : An integer.
Return value
Changes the Date object in place, and returns its new timestamp. If yearValue is NaN (or other values that get coerced to NaN, such as undefined), the date is set to Invalid Date and NaN is returned.
Description
If yearValue is a number between 0 and 99 (inclusive), then the year for
dateObj is set to 1900 + yearValue. Otherwise, the year for
dateObj is set to yearValue.
Examples
Using setYear()
The first two lines set the year to 1996. The third sets the year to 2000.
const theBigDay = new Date();
theBigDay.setYear(96);
theBigDay.setYear(1996);
theBigDay.setYear(2000);