javascript datum addieren
strdate = "2018-03-20";
thedate = new Date(strdate);
thedate.setDate(thedate.getDate() + 1); // 1 Tag dazu addieren
d = thedate.getDate();
m = thedate.getMonth();
y = thedate.getFullYear();
alert(d+"."+m+"."+y);
alert(thedate);