— now I unterstand what you want. Look of this works for you
| Global number year = 0
| Global number month = 0
| Global number day = 0
| Global number myUnixtime =0
| Global string DateV = "2018.4.29"
| Global number daysToAdd = 21
+ System: On start of layout
-> System: Set myUnixtime to Browser.ExecJS("Date.parse("&DateV&")")
-> System: Set myUnixtime to myUnixtime+daysToAdd×86400000
-> Browser: Execute javascript "this.myDate = new Date("&myUnixtime&")"
-> System: Set day to Browser.ExecJS("this.myDate.getDate()")
-> System: Set month to Browser.ExecJS("this.myDate.getMonth()")+1
-> System: Set year to Browser.ExecJS("this.myDate.getFullYear()")
-> Text: Set text to year&"."&month&"."&day