Invalidating dates can be done a couple different ways. See options below.
Exact dates (2018/2/13, 2018/2/16, 2018/2/17)
Recurring dates (12/24, 12/25, 12/26)
Weekdays (Saturdays, Sundays)
Date ranges (between 2018/12/21 and 2018/12/31)
Invalid dates can be overriden to be valid. In the following example dates between 2018/12/23 and 2018/12/29 are invalid, except 26th and 27th.
Overriding inside invalid ranges
Besides date objects you can use date strings and moment.js for invalids.
String (2018/07/10, 2018/07/14)
Moment JS (2018/09/19, 2018/09/20)