If you want to you can add days, minutes etc. to a date to change it.  Add this to dates.html:

var myDate=new Date('January 16, 1988');

This creates a date then changes one part by adding 1.  The second line might not make sense at first but keep looking:

  1. the bit in brackets is run first and it:
    1. gets the current date part
    2. adds 1 to that
  2. that new value is then stored in myDate by using the setDate method

You could have added years or seconds instead.

There are now quite a few dates in date.html so you might want to comment the various lines of code (or at least the blocks) so that it is clear what each one shows.