How do I fire a custom event from Polymer Dart?

Question

I want to fire/send/emit a custom event from inside a Polymer element. For example, I want to convert a normal DOM event like \"changed\" to a more semantic event like \"tod

Answer 1

Step 1

Capture the change events on the . Notice the on-change below.

Step 2

Handle the change event in the custom element code that contains the checkbox.

import 'package:polymer/polymer.dart';
import 'dart:html';
import 'models.dart';

@CustomTag('todo-item')
class TodoItemElement extends PolymerElement with ObservableMixin {
  @observable Item item;

  bool get applyAuthorStyles => true;

  void change(Event e, var details, Node target) {
    // do stuff here
  }
}

Notice the change event handler. That method is run any time the checkbox state changes.

Step 3

Dispatch a custom event.

  void change(Event e, var details, Node target) {
    dispatchEvent(new CustomEvent('todochange'));
  }

NOTE: the custom event name must not contain dashes.

Step 4

Listen for the custom event in a parent custom element.

Notice the use of on-todochange.

Enjoy!