A function that adds and subtracts decades from a Date object.
Date
Copy CodeaddDecades(new Date(2016, 5, 1), 5); // 2066-6-1 addDecades(new Date(2016, 5, 1), -5); // 1966-6-1
addDecades(new Date(2016, 5, 1), 5); // 2066-6-1 addDecades(new Date(2016, 5, 1), -5); // 1966-6-1
The number of decades to add or subtract from the date.
Date - A new Date instance.