SMART datagrid v.1 > Classes > GroupRow
When summaryMode of GridBase.rowGroup is not NONE, it will return the sum of field values specified by parameter field among data row of belonging to this group.
$('#getSum').click(function () {
var row = grid.focusedRow();
if (row instanceof GroupRow) {
var avg = row.getSum(0);
$('#sum').val(sum);
}
});