I am not sure about that but I remember reading somewhere that HTML5 datepickers are based on browser locale and might not give you desired output in all your visitors' browsers. E.g. in the US the date format is MM/dd/yyyy whereas in the UK it is dd/MM/yyyy.
I didn't want to deal with all that or leave it to luck so I ended up using jQueryUI datepicker.. Many events are already readily available for you there...