Possible Duplicate:
How to add months to a date in JavaScript?
What’s the simplest way to add X numbers of months to a date object but keep the day number? My date’s will always be the first of the month.
Examples:
If my start date is “04/01/2012” and i need to add 4 months to it, the result will be “08/01/2012”.
If my start date is “10/01/2012” and i need to add 4 months to it, the result will be “02/01/2013”.
Try something like
date.setMonth(date.getMonth()+4). This will automatically catch the overflow condition and add one to the Year.