Handle Grid Exception in Javascript

[Atchut]

Hello,
           var strClientID = getClientID(obj.id, "chkSelectAll") + "RgGridCt";
            var stClientRi = getClientID(obj.id, "chkSelectAll") + "RgGridR";
            var strClientRe = getClientID(obj.id, "chkSelectAll") + "rgGridRe";
       
    tableView = $find(strClientID).get_masterTableView();

In the above code, if the grid is not rgGridCt, tableview is throwing error.

In my page, I am having 3 different grids. If I select one of them, how can I pass the correct value so that tableview will not throw error.

TIA