Define custom event listener in dart code, not html markup

Question

In this useful post we can learn how to listen to dispatched custom events by way of inline markup in the template: How do I fire a custom event from Polymer Dart? I wonder if it's possible to do the same in the dart-script when custom elements are dynamically created, like this:

var myElement = new Element.tag('my-element');

possible duplicate of [How do you register for custom events in Dart using the new streams API](http://stackoverflow.com/questions/14820756/how-do-you-register-for-custom-events-in-dart-using-the-new-streams-api) — Günter Zöchbauer, Feb 14 '14 at 10:33
The referenced question is not about polymer so I added an answer. — Günter Zöchbauer, Feb 14 '14 at 10:49

score 4 · Accepted Answer · answered Feb 14 '14 at 10:48

4

You need for each event handler in your component an EventStreamProvider (static)
and a getter for easy access.

static const EventStreamProvider<CustomEvent> logoutEvent = 
    const EventStreamProvider<CustomEvent>("my-logout");
Stream<CustomEvent> get onLogout =>  MyElement.logoutEvent.forTarget(this);

You fire an event like

this.dispatchEvent(new CustomEvent("my-logout", detail: {'someData': 'bla'}));

// Polymer provides a shortcut for this
fire('my-logout', detail: {'someData': 'bla'});

You subscribe to this event like

mySesson.onLogout.listen((e) => doSomething());

answered Feb 14 '14 at 10:48

Günter Zöchbauer

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Just a little note. I suppose 'mySesson' is a little copy/paste typo. It's supposed to be the dynamically created custom element. – burktelefon Feb 14 '14 at 11:15
I just used a name that fit with the example logout event. That is just the name of a variable referencing a component. – Günter Zöchbauer Feb 14 '14 at 11:17

Define custom event listener in dart code, not html markup

1 Answers1