Angular

Passing event data

• You can pass value when emitting data
• The value is available to all subscribers of the event

this.change.emit(this.isSelected);

• In eventbinding, specify event object
• $event built-in object in angular
• In custom components $event represents custom event data
• In button click $event represents standard DOM event object

(change)="onFavoriteChanged($event)"

• In the handler add parameter

onFavoriteChanged(isSelected) {
}

Passing event data - complex value

• You can pass complex data when emitting event

this.change.emit({newValue: this.isSelected});

• In eventbinding, specify event object

 (change)="onFavoriteChanged($event)"

• In the handler add parameter

onFavoriteChanged(eventArgs) {
	console.log(eventArgs)
}

Using inline type annotation for event args

onFavoriteChanged(eventArgs: {newValue: boolean}) {
	console.log(eventArgs)
}

Using interface for event args

interface FavoriteChangedEventArgs {
	newValue: boolean
}
onFavoriteChanged(eventArgs: FavoriteChangedEventArgs) {
	console.log(eventArgs)
}