JavaScript 1.0; JScript 1.0; ECMAScript v1
date.setMonth(month) date.setMonth(month, day)
month
An integer between 0 ( January) and 11 (December) that is set as the month value (in local time) for the Date object date. Note that months are numbered beginning with 0, while days within the month are numbered beginning with 1.
day
An optional integer, between 1 and 31 that is used as the new value (in local time) of the day-of-month field of date. This argument is not supported prior to ECMAScript standardization.
The millisecond representation of the adjusted date. Prior to ECMAScript standardization, this method returns nothing.