Use the following JavaScript for the calculation script for DateField1:
var AddDays = 0;
// select action on value of DropList1 to set days to add
switch(DropDownList1.formattedValue) {
case "1":
AddDays = 1;
break;
case "2":
case "4":
AddDays = 2;
break;
case "3":
AddDays = 3;
break;
case "5":
case "7":
AddDays = 4;
break;
case "6":
AddDays = 5;
break;
default:
AddDays = 0;
break;
} // end shitch
var oCurrDate = new Date(); // get the curred date object
var fYear = oCurrDate.getFullYear(); // get full year
var fMonth = oCurrDate.getMonth(); // get current month
var fDate = oCurrDate.getDate(); // get current date
// fix text display for days to add
if (AddDays == 1) $.TextField2.formattedValue = AddDays + " day";
else $.TextField2.formattedValue = AddDays + " days";
// some debugging and tracing information
console.show(); console.clear();
console.println(DropDownList1.rawValue + " a:" + AddDays + " y:" + fYear + " m:" + fMonth + " d:" + fDate);
console.println( new Date(fYear, fMonth, (fDate + AddDays) ) );
console.println(util.printd("mm/dd/yyyy", new Date(fYear, fMonth, (fDate + AddDays)) ) );
console.println(AddDays + " days");
// format comuted date for display
$.formattedValue = util.printd("mm/dd/yyyy", new Date(fYear, fMonth, (fDate + AddDays)) );