Date.prototype.setYear()

The legacy setYear() method 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 to 1900; so date.setYear(22) results in the year value being set to 1922, and date.setYear(61) results in the year value being set to 1961. (In contrast, while new Date(61, 1) also results in the year value being set to 1961, new Date("2/1/22") results in the year value being set to 2022; 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 to 0061, and date.setFullYear(22) results in the year value being set to 0022.

Because of those differences in behavior, you should no longer use the legacy setYear() method, but should instead use the preferred setFullYear() method.

yearValue

An integer.

The number of milliseconds between 1 January 1970 00:00:00 UTC and the updated date.

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.

The first two lines set the year to 1996. The third sets the year to 2000.

var theBigDay = new Date();

theBigDay.setYear(96);
theBigDay.setYear(1996);
theBigDay.setYear(2000);

• Polyfill of Date.prototype.setYear in core-js
• Date.prototype.getFullYear()
• Date.prototype.getUTCFullYear()
• Date.prototype.setFullYear()
• Date.prototype.setUTCFullYear()