Modifying TJSArray object members

[rlsdevine]

I'm actually using pas2js from TMS WebCore (Delphi) but this question seems to be a pas2js thing. I have a TJSArray (retrieved via JSON from an API call) that holds a number of objects that define users, e.g. in Object Pascal:

Code: Pascal  [Select][+][-]

1.   TUser = record
2.     FirstName: string;
3.     Surname: string;
4.     DisplayName: string;
5.   end;

My TJSArray is a private field variable of the class:

Code: Pascal  [Select][+][-]

1.   private
2.     FUserList: TJSArray;

I'm testing different ways of modifying members of the array:

Code: Pascal  [Select][+][-]

1.   // -- The following works correctly.
2.   asm
3.     this.FUserList[0].DisplayName = "Bob1";
4.   end;
5.   console.log('DisplayName: ' + TUser(FUserList[0]).DisplayName);
6.  
7.   // -- The following line fails to compile: "Variable identifier expected".
8.   //TUser(FUserList[0]).DisplayName := 'Bob2';
9.   //console.log('DisplayName: ' + TUser(FUserList[0]).DisplayName);
10.  
11.   // -- The following works correctly.
12.   TJSObject(FUserList[0]).Properties['DisplayName'] := 'Bob3';
13.   console.log('DisplayName: ' + TUser(FUserList[0]).DisplayName);

The puzzle is that I can hard cast TUser(FUserList[0]) to get the DisplayName for the console output, but can't get it to compile when setting the value. Obviously not a show-stopper but curious how to get around this. I also tried (FUserList[0] as TUser) but that won't compile either.

Thanks, Bob