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I want a child element to dispatch a custom event and the parent element to listen for it, and take some action. How do I do this when working with Polymer?
568
You can dispatch a custom event from a polymer-element like this:
dispatchEvent(new CustomEvent('nameOfEvent'));
Then, parent element can listen for the custom event like this:
<child-element on-childspeaks="fireAway"></child-element>
Here is a more complete example showing how this works. First, here is the code for the child element:
<!DOCTYPE html>
<polymer-element name="child-element">
<template>
<div on-click="dispatch">I am a child</div>
</template>
<script type="application/dart">
import 'dart:html';
import 'package:polymer/polymer.dart';
@CustomTag('child-element')
class ChildElement extends PolymerElement with ObservableMixin {
dispatch(Event e, var detail, Node sender) {
print('dispatching from child');
dispatchEvent(new CustomEvent('childspeaks'));
}
}
</script>
</polymer-element>
And here is the code for the parent element:
<!DOCTYPE html>
<link rel="import" href="child_element.html">
<polymer-element name="parent-element">
<template>
<div>I am the parent</div>
<child-element on-childspeaks="fireAway"></child-element>
</template>
<script type="application/dart">
import 'dart:html';
import 'package:polymer/polymer.dart';
@CustomTag('parent-element')
class ParentElement extends PolymerElement with ObservableMixin {
void fireAway() {
window.alert('The child spoke, I hear');
}
}
</script>
</polymer-element>
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