What is the possible order of life cycle hooks
The Eduladder is a community of students, teachers, and programmers just interested to make you pass any exams. So we solve previous year question papers for you.
See Our team
Wondering how we keep quality?
Got unsolved questions?

Ask Questions
Hey! Want to work with us? Our youtube channel See our Jd Want to apply? Do it today

Use Me  ?

New searches
Operating-Systems-10CS53-unit-4-->View question


What is the possible order of life-cycle hooks?




By:13priya

Taged users:
|prajwalamv

Likes:
Be first to like this question

Dislikes:
Be first to dislike this question

Talk about thisDelete|Like|Dislike|


Answers

A component has a lifecycle managed by Angular.

Angular creates it, renders it, creates and renders its children, checks it when its data-bound properties change, and destroys it before removing it from the DOM.

Angular offers lifecycle hooks that provide visibility into these key life moments and the ability to act when they occur.

A directive has the same set of lifecycle hooks, minus the hooks that are specific to component content and views.

Component lifecycle hooks overview

Directive and component instances have a lifecycle as Angular creates, updates, and destroys them. Developers can tap into key moments in that lifecycle by implementing one or more of the lifecycle hook interfaces in the Angular core library.

Each interface has a single hook method whose name is the interface name prefixed with ng. For example, the OnInit interface has a hook method named ngOnInit() that Angular calls shortly after creating the component:

peek-a-boo.component.ts (excerpt)
 content_copy
export class PeekABoo implements OnInit {
  constructor(private logger: LoggerService) { }

  // implement OnInit's `ngOnInit` method
  ngOnInit() { this.logIt(`OnInit`); }

  logIt(msg: string) {
    this.logger.log(`#${nextId++} ${msg}`);
  }
}
No directive or component will implement all of the lifecycle hooks and some of the hooks only make sense for components. Angular only calls a directive/component hook method if it is defined.

Lifecycle sequence

After creating a component/directive by calling its constructor, Angular calls the lifecycle hook methods in the following sequence at specific moments:

Hook Purpose and Timing
ngOnChanges()
Respond when Angular (re)sets data-bound input properties. The method receives a SimpleChanges object of current and previous property values.
Called before ngOnInit() and whenever one or more data-bound input properties change.
ngOnInit()
Initialize the directive/component after Angular first displays the data-bound properties and sets the directive/component's input properties.
Called once, after the first ngOnChanges().
ngDoCheck()
Detect and act upon changes that Angular can't or won't detect on its own.
Called during every change detection run, immediately after ngOnChanges() and ngOnInit().
ngAfterContentInit()
Respond after Angular projects external content into the component's view.
Called once after the first ngDoCheck().
A component-only hook.
ngAfterContentChecked()
Respond after Angular checks the content projected into the component.
Called after the ngAfterContentInit() and every subsequent ngDoCheck().
A component-only hook.
ngAfterViewInit()
Respond after Angular initializes the component's views and child views.
Called once after the first ngAfterContentChecked().
A component-only hook.
ngAfterViewChecked()
Respond after Angular checks the component's views and child views.
Called after the ngAfterViewInit and every subsequent ngAfterContentChecked().
A component-only hook.
ngOnDestroy
Cleanup just before Angular destroys the directive/component. Unsubscribe Observables and detach event handlers to avoid memory leaks.
Called just before Angular destroys the directive/component.

13priya

Likes:
Be first to like this answer

Dislikes:
Be first to dislike this answer
Talk about this|Once you have earned teacher badge you can edit this questionDelete|Like|Dislike|
------------------------------------

Can you help us to add better answer here? Please see this



Not the answer you're looking for? Browse other questions from this Question paper or ask your own question.

Join eduladder!