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Anubhav Kumar

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The Anubhav portal was launched in March 2015 at the behest of the Hon'ble Prime Minister for retiring government officials to leave a record of their experiences while in Govt service .

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Anubhav Kumar

Anubhav Kumar

22-Dec-2025

In Angular, @Output() is used to send data or events from a child component to its parent component.

@Output() allows a child component to emit events that the parent component can listen to and react to.

Think of it as:

Child → Parent communication

Why @Output is Needed

Angular components are isolated. A child component cannot directly change parent data.

So Angular provides:

  • @Input() → Parent ➜ Child
  • @Output() → Child ➜ Parent

Basic Definition

@Output() eventName = new EventEmitter<T>();
  • @Output() marks an event
  • EventEmitter emits data
  • Parent listens using event binding

Simple Example

Child Component

import { Component, Output, EventEmitter } from '@angular/core';

@Component({
  selector: 'app-child',
  template: `
    <button (click)="sendData()">Send to Parent</button>
  `
})
export class ChildComponent {
  @Output() message = new EventEmitter<string>();

  sendData() {
    this.message.emit('Hello Parent!');
  }
}

Parent Component

<app-child (message)="receiveMessage($event)"></app-child>
export class ParentComponent {
  receiveMessage(data: string) {
    console.log(data); // Hello Parent!
  }
}

How It Works (Internally)

  • Child emits event:
this.message.emit(value);
  • Parent listens:
(message)="receiveMessage($event)"
  • $event contains emitted value

Custom Event Names

@Output('close') closePopup = new EventEmitter<void>();
<app-child (close)="onClose()"></app-child>

Emitting Objects

@Output() userSelected = new EventEmitter<User>();
this.userSelected.emit({ id: 1, name: 'Anna' });
<app-child (userSelected)="onUser($event)"></app-child>

@Output vs Callback Function

Bad practice:

@Input() callback!: Function;

Correct Angular way:

@Output() action = new EventEmitter();

Best Practices

  • Use @Output only for events, not data storage
  • Keep event names verb-based (saved, deleted)
  • Avoid heavy logic inside child
  • Prefer Observable for complex streams

Real-World Example

  • Modal close button
  • Form submit event
  • Delete confirmation
  • Dropdown selection change
  • Summary (One Line)
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