I'm having this function in JavaScript for some reason the focusedKeyValue is not being set, I'm not sure that is the e.customArgs, I wanted to ask I someone else know about another way to do it it is a session variable.

    function OnBeginCallback(s, e) {
        e.customArgs["focusedKeyValue"] = s.GetRowKey(s.GetFocusedRowIndex());
    }