VietMX Staff asked 3 years ago
A component in Angular has a life-cycle, a number of different phases it goes through from birth to death. We can hook into those different phases to get some pretty fine grained control of our application.
- constructor This is invoked when Angular creates a component or directive by calling new on the class.
- ngOnChanges Invoked every time there is a change in one of th input properties of the component.
- ngOnInit Invoked when given component has been initialized. This hook is only called once after the first ngOnChanges
- ngDoCheck Invoked when the change detector of the given component is invoked. It allows us to implement our own change detection algorithm for the given component.
- ngOnDestroy This method will be invoked just before Angular destroys the component. Use this hook to unsubscribe observables and detach event handlers to avoid memory leaks.
These hooks are only called for components and not directives.
- ngAfterContentInit Invoked after Angular performs any content projection into the components view (see the previous lecture on Content Projection for more info).
- ngAfterContentChecked Invoked each time the content of the given component has been checked by the change detection mechanism of Angular.
- ngAfterViewInit Invoked when the component’s view has been fully initialized.
- ngAfterViewChecked Invoked each time the view of the given component has been checked by the change detection mechanism of Angular.
