In virtual mode, the Tree Grid is created on demand. In this case, Child records are created and initialized when the parent record is expanded. For example when you expand a record, jqxTreeGrid makes an Ajax request to http://services.odata.org. The request contains the expanded record's EmployeeID and as a result we get all sub records whose "ReportsTo" data field match the "EmployeeID" data field. Data Source: "http://services.odata.org"