Disabling aspxgridviews on server-side, how to handle on client-side?

Question

I've just started a project where our BA guy needs me to disable all of our aspxgridviews past a certain time.

C#
     public void CutoffDateTime()
      {
          //DateTime today = DateTime.Now; // this will be for live code
          DateTime today = new DateTime(2016, 4, 15, 7, 00, 00); // for testing
          DateTime cutoff = new DateTime(2016, 4, 19, 7, 00, 00);

          if (today >= cutoff.AddDays(7))
          {
              cutoff = cutoff.AddDays(7);
          }
          // if today is past cutoff, disable all grids
          if (today < cutoff.AddHours(-55))
          {
              gvProduction.Enabled = false;
              gvProductionSummary.Enabled = false;
              gvDowntimeSummary.Enabled = false;
              gvNonProd.Enabled = false;
              cbCutoff.Checked = false;
          }
          else
              cbCutoff.Checked = true;
    }

The grids are disabled correctly, but this affects some client-side code that calls the grid.Refresh() methods.

I've added the checkbox as an invisible control so that I can easily interface with the client-side and I'm trying to add:

JS
    if (cbCutoff.GetChecked()==true)
        grid.Refresh();

But I am still getting JavaScript runtime errors stating that 'cbCutoff is undefined' but I can't think of another way to accomplish this task.

Thanks

EDIT :

Here is part of my asp.net markup that I'm trying to fix via DexExpress' GetChecked() method that returns true if checked:

aspx

<ClientSideEvents ActiveTabChanged="function(s, e) {
    if (e.tab.index.toString() ==  1 && cbCutoff.GetChecked()==true)
        gridProductionSummary.Refresh();
}" />

Answer 1

Fixed by using

    if (cb.GetChecked())
grid.Refresh();

and set the checkbox to enabled on server-side