I am using pikaday and it is a really decent datapicker. Is it possible to mark or highlight certain dates? This can help users distinguish "normal" dates from some "important" dates for them at first glance.
You can add an array of dates to the property events :
events
an array of events that you would like to distinguish from regular days (for example, [Sat 28 Jun 2017, "Sun 29 Jun 2017", "Tuesday 01.07.2017",])
https://github.com/dbushell/Pikaday#configuration