How to attach event "onAfterLoad" (or other needed event after get data) to combo?

I want to set value in combo after load data by url.
Some code:
var client_list = $$(“client”).getPopup().getList();
client_list.clearAll();
var setIdEvent = $$(“client”).attachEvent(“onAfterLoad”, webix.once(function(){
console.log($$(“client”).getPopup().getList());
$$(‘client’).setValue(data);
}) );
client_list.load(‘someUrL’);

And I tried this but unfortunately.
client_list.waitData.then(function(){
console.log(‘w’);
$$(‘client’).setValue(data);
});

I found mistake → must attach event to ‘client_list’