该方法接受当前和上一属性值的SimpleChanges对象当被绑定的输入属性的值发生变化时调用,首次调用一定会发生在ngOnInit()之前。
CreateanewObservablethepublishesonlytheNavigationStarteventthis.navStart=router.events.pipe(filter(evt=>evtinstanceofNavigationStart))asObservable<NavigationStart>;} ngOnInit
/heroes.component.css']})exportclassHeroesComponentimplementsOnInit{constructor(){}ngOnInit(){}} 你要从Angular
content_copygetHeroes():void{this.heroes=this.heroService.getHeroes();} 在ngOnInit中调用它 你固然可以在构造函数中调用getHeroes
'app/app.component.css']})classAppComponentimplementsOnInit{title='TourofHeroes'; heroes:Hero[]=[]; ngOnInit
exportclassHeroBioComponentimplementsOnInit{@Input()heroId:number; constructor(privateheroCache:HeroCacheService){} ngOnInit
content_copyexportclassHeroListComponentimplementsOnInit{heroes:Hero[];selectedHero:Hero;constructor(privateservice:HeroService){}ngOnInit
hero-detail.component.css']})exportclassHeroDetailComponentimplementsOnInit{@Input()hero:Hero; constructor(){} ngOnInit
在ngOnInit()生命周期钩子中调用getHeroes。 这个getHeroes函数把要显示的英雄的数量缩减为四个(第二、第三、第四、第五)。
adHost:AdDirective;interval:any;constructor(privatecomponentFactoryResolver:ComponentFactoryResolver){}ngOnInit
){} //Pushasearchtermintotheobservablestream.search(term:string):void{this.searchTerms.next(term);} ngOnInit
(comp.welcome).toBeUndefined();});it('shouldwelcomeloggedinuserafterAngularcallsngOnInit',()=>{comp.ngOnInit
heroes.component.css']})exportclassHeroesComponentimplementsOnInit{ heroes=HEROES; selectedHero:Hero; constructor(){} ngOnInit
例如,OnInit接口的钩子方法名为ngOnInit。 Angular会按以下顺序调用钩子方法: ngOnChanges-在输入属性(input)/输出属性(output)的绑定值发生变化时调用。
exportclassInjectorComponentimplementsOnInit{car:Car; heroService:HeroService;hero:Hero; constructor(privateinjector:Injector){} ngOnInit
src/app/heroes/hero-detail.component.ts(ngOnInit) content_copyngOnInit(){this.hero$=this.route.paramMap.pipe
exportclassCountdownTimerComponentimplementsOnInit,OnDestroy{ intervalId=0;message='';seconds=11; clearTimer(){clearInterval(this.intervalId);} ngOnInit
privatesearchText$=newSubject<string>(); search(packageName:string){this.searchText$.next(packageName);} ngOnInit