>It seems something as simple as:
>
>

>   if (LevelExtremeListHeight)
>   {
>      var oH=LevelExtremeListHeight
>   }
>

>
>does it.

You may try using the TRY / CATCH.

var oH = 0;
try {
     if (LevelExteremaListHeight)
     {
         oH = LevelExteremaListHeight
     }
CATCH {
     oH = <somedefault value or don't change>
}

I thought there was a function similar to VARTYPE, but I may be thinking of VBscript.

I use too many languages.