Angular, a powerful front-end framework, provides developers with various tools to create dynamic and interactive web applications.

Among these tools are Input and Output decorators, essential features that enhance the modularity and flexibility of Angular components.

Input Decorator

The Input decorator in Angular is a mechanism for passing data from a parent component to a child component.

This is particularly useful when you want to make your components more reusable and configurable. Here’s how you can use the Input decorator:

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

@Component({
  selector: 'app-child',
  template: '<p>{{ childMessage }}</p>',
})
export class ChildComponent {
  @Input() childMessage: string;
}

In this example, the @Input decorator is applied to the childMessage property. Now, you can bind data to this property when using the app-child component in a parent component:

<app-child [childMessage]="parentMessage"></app-child>

Output Decorator

The Output decorator, on the other hand, facilitates communication from a child component to a parent component.

It allows a child component to emit events that a parent component can listen for and respond to. Here’s a simple example:

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

@Component({
  selector: 'app-child',
  template: '<button (click)="sendMessage()">Send Message</button>',
})
export class ChildComponent {
  @Output() messageEvent = new EventEmitter<string>();

  sendMessage() {
    this.messageEvent.emit('Hello from child!');
  }
}

In this case, the @Output decorator is used to create an EventEmitter named messageEvent. The sendMessage method emits a message when the button is clicked. In the parent component, you can capture this event like so:

<app-child (messageEvent)="receiveMessage($event)"></app-child>
import { Component } from '@angular/core';

@Component({
  selector: 'app-parent',
  template: '<p>{{ receivedMessage }}</p>',
})
export class ParentComponent {
  receivedMessage: string;

  receiveMessage(message: string) {
    this.receivedMessage = message;
  }
}

These Input and Output decorators significantly contribute to the creation of modular and maintainable Angular applications.

By leveraging these features, developers can build components that are decoupled, promoting a more efficient and scalable development process.

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