What are recommanditions for @Output event names (to prevent native event name collision)?
I have played with Angular 2 components and their compositions and I have run into ugly behavior, which is caused by native event bubbling and @Output name collision.
I have component app-form with form in template
<form (ngSubmit)="submitButtonClicked($event)">
<input type="text"/>
<button type="submit">Send</button>
</form>
I use this form component in app-middle component, which has own event emitter with name submit.
@Component({
selector: 'app-middle',
templateUrl: './middle.component.html',
styleUrls: ['./middle.component.css']
})
export class MiddleComponent implements OnInit {
@Output() submit = new EventEmitter<string>();
constructor() { }
emitSubmitEvent() {
this.submit.emit("some data");
}
}
template:
<div>
<app-form></app-form>
</div>
And app component with template:
<app-middle (submit)="submitListener($event)"></app-middle>
Now, submitListener will be called
- when submit on app-middle is called (wanted behavior)
- when form is submitted, because native event bubble to the top ("parasitic" behavior)
I suppose, "parasitic" behavior is based on DOM event bubbling. I can stop it by event.stopPropagation() in submitButtonClicked handler, but if I forgot stop it, I get pretty ugly errors.
Generally, I consider this behavior quite dangerous. If I am not wrong, every event binding expression handler can be potentially called "parasitically" by native event from inner components. if has same name as any of DOM events (https://developer.mozilla.org/en-US/docs/Web/Events) And I don't talk about forward compatibility....
Same problem you can see here: https://bitbucket.org/winsik/submit-event-issue/src
Did you run into this problem? How do you name your @Outputs?
Answer
I'm prefixing @Output events with the name of my components, which seems to work pretty well and to provide a consistent and clear convention which avoids the problems you describe. For example, suppose I have a component named, e.g. TurnEditorComponent -- @Output events might be named turnEditorChange, turnEditorFocus, turnEditorBlur and so on.