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Mini Bhati
Mini Bhati

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How to respond to input changes reactively in the child component

Component interaction can work in one of the following three ways:

  • ngOnChanges() lifecycle hooks
  • Setters on the @Input() property
  • Services

If your component is a presentational component and interacts only with the @Input() and @Output() properties, then using **setters is the most reactive way **of interacting with the child component

Let's understand how!

Parent Child Component Interaction

Parent component passes value to the child component with the following syntax where userValue is an @Input() property in the child component

<child-component [userValue]="userValue"></child-component>
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export class ChildComponent {
  @Input() userValue;
}
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Setters on the @Input() property

Setters on the @Input() property runs some additional logic whenever the input changes.
So, instead of defining userValue, we define a function on the userValue property which executes whenever input changes.

export class ChildComponent {
  status = false;
  @Input() set userValue(value: string) {
      this.status = true;
  }
}
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These are called property accessor methods which executes on setting/getting values. Add a set keyword before a property to make a setter.


Thanks for reading!

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