Angular Lifecycle Hooks And How They Are Used In Angular

In Angular, a component goes through a lifecycle of events as it is created, rendered, and destroyed. Angular provides lifecycle hooks, such as ngOnInit and ngOnDestroy, that allow you to tap into these events and perform operations at specific points in the lifecycle.

Here is an overview of the most commonly used Angular lifecycle hooks:

• ngOnChanges: This hook is called when an input binding value changes. It is called before the ngOnInit hook and can be used to react to changes in input values.
• ngOnInit: This hook is called after the component’s constructor and after the first ngOnChanges hook. It is a good place to put initialization logic for the component.
• ngDoCheck: This hook is called during every change detection run, and it can be used to implement custom change detection logic for the component.
• ngAfterContentInit: This hook is called after the component’s content (transcluded content) has been initialized.
• ngAfterContentChecked: This hook is called after the component’s content (transcluded content) has been checked.
• ngAfterViewInit: This hook is called after the component’s view (child components) has been initialized.
• ngAfterViewChecked: This hook is called after the component’s view (child components) has been checked.
• ngOnDestroy: This hook is called just before the component is destroyed. It can be used to clean up any remaining resources or subscriptions.

These lifecycle hooks can be used to perform tasks such as setting up subscriptions, making HTTP requests, and updating the component’s view. They are an important part of Angular’s component architecture and can help you build more efficient and maintainable components.

To use a lifecycle hook, you simply need to implement the hook method in your component class. For example, to use the ngOnInit hook, you would write the following in your component class:

export class MyComponent implements OnInit {
  ngOnInit() {
    // Initialization logic goes here
  }
}

It’s important to note that the order in which the lifecycle hooks are called is fixed, and certain hooks may not be called at all depending on the state of the component. You should also be aware of the difference between change detection runs and lifecycle events, as they can be easy to confuse. By understanding the lifecycle of a component and how to use the lifecycle hooks provided by Angular, you can build more powerful and dynamic components.