The signature of a function used as a canDeactivate guard on a Route.

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type CanDeactivateFn<T> = (component: T, currentRoute: ActivatedRouteSnapshot, currentState: RouterStateSnapshot, nextState: RouterStateSnapshot) => Observable<boolean | UrlTree> | Promise<boolean | UrlTree> | boolean | UrlTree;

See also

• Route

Description

If all guards return true, navigation continues. If any guard returns false, navigation is cancelled. If any guard returns a UrlTree, the current navigation is cancelled and a new navigation begins to the UrlTree returned from the guard.

The following example implements and uses a CanDeactivateFn that checks whether the user component has unsaved changes before navigating away from the route.

@Component({template: ''})
export class UserComponent {
  hasUnsavedChanges = true;
}

bootstrapApplication(App, {
  providers: [provideRouter([
    {
      path: 'user/:id',
      component: UserComponent,
      canDeactivate: [(component: UserComponent) => !component.hasUnsavedChanges],
    },
  ])]
});