onColumnGroupCollapse

fires when grouped columns are either collapsed or expanded

void onColumnGroupCollapse(string column_id,string batch_id,boolean is_opened);

column_id	string	the ID of the aggregating column (the column that unites the batch)
batch_id	string	the ID of the batch to which the collapsed/expanded columns belong
is_opened	boolean	signals that the columns were collapsed (false) or expanded (true)

Example

const batchStates = {
  batch1:false,
  batch2:false
};
$$("datatable1").attachEvent("onColumnGroupCollapse",function(colId, btchId, open){
  batchStates[btchId] = open;
});