The setYear() method sets the year in the Date object to the argument year. The argument can be either a four-digit or two-digit integer.
To create a two-digit representation, subtract 1900 from the desired date. The method returns an integer representing the number of milliseconds between midnight January 1, 1970 (GMT) to the new date.
<html>
<script language="JavaScript">
<!--
theDate = new Date();
document.write("Initial milliseconds=",theDate.getTime());
document.write("<br>setYear returned ");
document.write(theDate.setYear(83)," milliseconds.")
document.write("<br>Final milliseconds=",theDate.getTime());