set the year and, optionally, the month and date fields of a Date
date.setFullYear(year) date.setFullYear(year, month) date.setFullYear(year, month, day)
year The year, expressed in local time, to be set in date. This argument should be an integer that includes the century, such as 1999; it should not be an abbreviation, such as 99.
month An optional integer between 0 and 11 that is used as the new value (in local time) of the month field of date.
day An optional integer between 1 and 31 that is used as the new value (in local time) of the day-of-the-month field of date.
The internal millisecond representation of the adjusted date.