Auto generate login name basis on user first initial and last name... LC designer

Question

First initial + last name= login name...
Text field   + text field  = text field....
can I use javascript to generate the loginname form first name (first Int) and last name???
For ex... First name: John
             middle int: k
             last Name: Doe
            LoginName: jdoe
var LoginName = getField("LastName").value;
         var FirstName = getField("FirstName").value;
         if (FirstName!="")
         LoginName += " " + FirstName.substring(0,1) + "."
         event.value = LoginName;
not sure if this is right... please help

Answer 1

You guys are both using Acrobat JS notation so you're not going to have much luck.
In LC there's no getField or event.value and values are returned from fields using fieldName.rawValue (or .formattedValue).
I put this on the Calculate event of the LoginName field:
var vFirstName = FirstName.rawValue;
var vLastName = LastName.rawValue;
if (!(FirstName.isNull || LastName.isNull)) { // if both fields have data
this.rawValue = vFirstName.substring(0,1) + vLastName;