Как преобразовать следующую таблицу в JSON с помощью JavaScript?

Еще один способ:

Private Sub dgvGroups_CellValueChanged(sender As System.Object, e As System.Windows.Forms.DataGridViewCellEventArgs) Handles dgvGroups.CellValueChanged

    If Me.Visible = False Then Exit Sub ' Sub gets called on form load which causes problems

    wksGroups.Cells(e.RowIndex + 1, 1) = dgvGroups.Item(e.ColumnIndex, e.RowIndex).Value
    wksGroups.Cells(1, 5) = dgvGroups.RowCount