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Answer : Look into using OnInit lifecycle hook which is processed first when a component is loaded. Documentation For ngOnInit Thats simple enough, then move that call to the service as seen below into the life cycle hook. Give the class a public variable ie public toolTipData: string; (moved into OnInit) this.planService.getAuditDetails(planId, fieldName, fieldValue) .subscribe((auditDetail: AuditDetail) => { this.tooTipData = auditDetail.toolTipInfo // (guessing at name) this.auditDetail = auditDetail; this.loadCompleted = true); }, (errors) => { console.log(errors) // api error status code. } }); In the HTML set the tool tip value to [ngbTooltip]="toolTipData" This should help populate the tool tip appropriately. The asynchronous changes aren't showing up because NgbTooltip window uses ChangeDetectionStrategy.OnPush and the only way to trigger change detection is calling open() on a closed tooltip. In order t...

Answer : OnDestroy lifecycle hook is available in providers. According to the docs: Lifecycle hook that is called when a directive, pipe or service is destroyed. Here's an example: @Injectable() class Service implements OnDestroy { ngOnDestroy() { console.log('Service destroy') } } @Component({ selector: 'foo', template: `foo`, providers: [Service] }) export class Foo implements OnDestroy { constructor(service: Service) {} ngOnDestroy() { console.log('foo destroy') } } @Component({ selector: 'my-app', template: `<foo *ngIf="isFoo"></foo>`, }) export class App { isFoo = true; constructor() { setTimeout(() => { this.isFoo = false; }, 1000) } } Notice that in the code above Service is an instance that belongs to Foo component, so it can be destroyed when Foo is destroyed. For providers that belong to root injector this will happen on application destroy, t...