object.IsRootFolder 

function DisplayLevelDepth(pathspec)
{
   var fso, f, n, s = "";
   fso = new ActiveXObject("Scripting.FileSystemObject");
   f = fso.GetFolder(pathspec);
   n = 0;
   if (f.IsRootFolder)
      s = "The specified folder is the root folder."
   else
   {
      do
      { 
         f = f.ParentFolder;
         n++;
      }
      while (!f.IsRootFolder)
      s = "The specified folder is nested " + n + " levels deep."
   }
   return(s);
}

Function DisplayLevelDepth(pathspec)
   Dim fso, f, n
   Set fso = CreateObject("Scripting.FileSystemObject")
   Set f = fso.GetFolder(pathspec)
   If f.IsRootFolder Then
      DisplayLevelDepth = "The specified folder is the root folder."
   Else
      Do Until f.IsRootFolder
         Set f = f.ParentFolder
         n = n + 1
      Loop
      DisplayLevelDepth = "The specified folder is nested " & n & " levels deep."
   End If
End Function