ngOnDestroy warn user before exiting

Question

I am trying to find a way to alert user before exiting the screen. If they press "no" then it should not destroy. And if they press "ok" then carry on with destroy operations.

Does ngOnDestory has a event that happens before ngOnDestory? for example ngOnBeforeDestroying?

I am currently developing with Angular 4.

Search for canDeactivate guard.It allows you to control the navigating away from a particular page.So suppose there is a page which allows user to fill up a form.So after filling half of the form the user tries to go to another page, than we can use this guard to confirm user if he really wants to navigate, because his form data will be lost on navigating. — pritesh, Jun 18 '17 at 06:54

score 3 · Accepted Answer · answered Jun 18 '17 at 06:51

yes, you should be using canDeactivate route guard.

Create a injectable service

@Injectable()
class CanDeactivateService implements CanDeactivate<TeamComponent> {


  canDeactivate(
    component: TeamComponent,
    currentRoute: ActivatedRouteSnapshot,
    currentState: RouterStateSnapshot,
    nextState: RouterStateSnapshot
  ): Observable<boolean>|Promise<boolean>|boolean {
    return component.isDirty ;
 }
}

This can be used to determine if the page can be destroyed or not.

This should be configured in Routes as

RouterModule.forRoot([
      {
        path: '..', // path
        component: Comp, // name of the component
        canDeactivate: [CanDeactivateService]
      }
    ])
  ],

ngOnDestroy warn user before exiting

1 Answers1