In Dart why the code below (about MutationObserver) dose not work?
I modified one the Dart polymer example to test MutationObserver. It does not work! Any suggestion?
This is the HTML code:
-
It doesn't appear that mutation observer events can cross the shadow boundary.
If you put the
into a custom element, the mutation observers will work.Here is an example:
import 'package:polymer/polymer.dart'; import 'dart:html'; import 'dart:async'; @CustomTag("my-element") class MyElement extends PolymerElement with ObservableMixin { final Listtimestamps = toObservable([]); MutationObserver observer; created() { super.created(); observer = new MutationObserver(_onMutation); observer.observe(getShadowRoot('my-element').query('#timestamps'), childList: true, subtree: true); new Timer.periodic(const Duration(seconds: 1), (t) { timestamps.add(new DateTime.now().toString()); }); } // Bindings, like repeat, happen asynchronously. To be notified // when the shadow root's tree is modified, use a MutationObserver. _onMutation(List mutations, MutationObserver observer) { print('${mutations.length} mutations occurred, the first to ${mutations[0].target}'); } } The custom element:
- {{ts}}
The main HTML:
index
加载中...
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