How can I observe data-attributes of ZK elements?

Question

I want to execute something in backend, when the data-attribute of a ZK element changes.
There's a MutationObserver in Javascript, is there something similar in ZK that I can use?

I already checked the ZK Events class but there doesn't seem to be an event that listens to attribute changes.

Answer 1

There is no event listener or similar by default that would be triggered when changing a clientAttribute on a component.

Where does the change originate from? Is it an event happening at client-side? Or a change done on the component object in Java? Could you explain the use case? there might be a different way to achieve it:)

Edit: technical solution after exchanges. firing an event from client to server side: https://www.zkoss.org/wiki/ZK_Client-side_Reference/Communication/AU_Requests/Client-side_Firing#Fire_Event_Directly_to_Server

I'd recommend firing a "onCustom" event instead (any event name starting by "on"+yourEventName ). You will also need to use toServer:true in the event optional arguments to have it fired to the server directly. this one is a good option: zAu.send(new zk.Event(wgt, "onFoo", {foo: 'my data'}, {toServer:true})); where wgt is the widget object, "onFoo" is the custom event name, {foo: 'my data'} is the payload, if you need to send anything back to the server, and {toServer: true} is the optional arguments, with the toServer entry

the issue with firing onChange is that is is a default event sent by default actions. there is already behaviors tied to onChange on most components. you might trigger a default workflow which expects a specific payload and create an error situation. By sending a onCustomName (whathever it is, just not a default event) event, you are sure to only trigger the listener in by invoking the zAu.send