Right,
Maybe I should explain my case. I don't use the toolbar button to trigger the export to excel, but a different button:
$("#export-to-excel").on("click", function(e) {
grid.saveAsExcel();
});
So the export starts, but then e.sender.saveAsExcel(); triggers the export once again.
And in my case, it means a second call to the server, to get the data.
Which is not a good idea, because some customers have a lot of records to export.
So I need to trigger the excelExport event only once.