var spread = new GC.Spread.Sheets.Workbook(document.getElementById("ss"), { sheetCount: 3 });
var sheet = spread.getActiveSheet();
sheet.suspendPaint();
var sourceDataArray = [["Date", "Buyer", "Type", "Amount"],
["01-Jan", "Mom", "Fuel", 74],
["15-Jan", "Mom", "Food", 235],
["17-Jan", "Dad", "Sports", 20],
["19-Jan", "David", "Books", 120],
["20-Jan", "Dad", "Food", 160],
["21-Jan", "David", "Sports", 15],
["21-Jan", "Kelly", "Books", 125]];
sheet.setArray(3, 0, sourceDataArray);
sheet.tables.add('Table1', 3, 0, 8, 4);
sheet.setColumnWidth(6, 130);
sheet.setColumnWidth(8, 100);
var layout = GC.Spread.Pivot.PivotTableLayoutType.compact;
var theme = GC.Spread.Pivot.PivotTableThemes.medium2;
var options = {showRowHeader: true, showColumnHeader: true};
var pivotTable = sheet.pivotTables.add("PivotTable1", 'Table1', 3, 6, layout, theme, option);
var groupInfo = {
    originFieldName: "Buyer",
    textGroup: {
        "parent": ["Mom", "Dad"],
        "children": ["David", "Kelly"]
    }
};
pivotTable.group("FamilyMembers", groupInfo);
pivotTable.add("FamilyMembers", "FamilyMembers", GC.Spread.Pivot.PivotTableFieldType.rowField);
pivotTable.add("Buyer", "Buyer", GC.Spread.Pivot.PivotTableFieldType.rowField);
pivotTable.add("Amount", "Sum of Amount", GC.Spread.Pivot.PivotTableFieldType.valueField, GC.Pivot.SubtotalType.sum);
sheet.resumePaint();

pivotTable.ungroup("FamilyMembers");