how to get the value of particular cell value in JsGrid using "OnCellEditCompleted"

how to get the value of particular cell value instead of column title in JsGrid using "OnCellEditCompleted" event as below:

<script type="text/javascript">
    Type.registerNamespace("GridManager");

    GridManager = function () {
        this.Init = function (jsGridControl, initialData, props) {
            control = jsGridControl;
            var dataSource = new SP.JsGrid.StaticDataSource(initialData);
            var jsGridParams = dataSource.InitJsGridParams();

            // This event is triggered after the standard grid error checking.
            jsGridControl.AttachEvent(SP.JsGrid.EventType.OnCellEditCompleted, GotHere);

            jsGridControl.Init(jsGridParams);
        }
    };
    function GotHere(obj) {
        alert('Got Here, ' + obj.fieldKey);

    }
</script>

Thanks & Regards, Krishna