Hide a column if corresponding cell "is blank"/"formula is null" upon sheet's activation - vba

Question

I am new to VBAing but have a small amount of javascript knowledge and hoping for a bit of guidance/help as I can't seem to get the code working. There's probably some glaring mistakes so thanks for the patience.
I'm trying to get a spreadsheet to update a sheet upon that sheet's activation, where it will hide columns whose 2nd row cell is "blank" (or the formula x(y) in the cell is null).
Below is what have tried so far.
Private Sub Workbook_SheetActivate(ByVal Sh As Object)
If Sh.Name = "FSM" Then
Function hideBlankColumns()
i = 2
For i = 2 To 30
If IsNull(Cells(2, i).Value) = True Then
Columns(i).EntireRow.Hidden = True
Else: Columns(i).EntireRow.Hidden = False
End If
Next i
End Function
End If
End Sub
Thanks in advance!

Answer 1

You have three errors in your code:
you cannot define a function inside another sub.
you are talking about hiding/unhiding columns, but in the code you hide rows: Columns(lCol).EntireRow.Hidden = True
function IsNull always returns False if you pass Excel cell or its value as a parameter. In this case you should use function IsEmpty instead.
This code should work properly:
Private Sub Workbook_SheetActivate(ByVal Sh As Object)
Dim i As Integer
If Sh.Name = "FSM" Then
For i = 2 To 30
Columns(i).EntireColumn.Hidden = IsEmpty(Cells(2, i).value)
Next i
End If
End Sub

Answer 2

Try something like this.
Private Sub Workbook_SheetActivate(ByVal Sh As Object)
If Sh.Name = "FSM" Then
lCol = 2
Do While lCol <= ws.UsedRange.Columns.count
If IsNull(Cells(2, lCol).Value) = True Then
Columns(lCol).EntireColumn.Hidden = True
Else
Columns(lCol).EntireColumn.Hidden = False
End If
lCol = lCol + 1
Loop
End if
End sub