import { Injectable } from '@angular/core';
import { ActivatedRouteSnapshot, CanDeactivate, RouterStateSnapshot } from '@angular/router';
import { SubAComponent } from './sub-a.component';

@Injectable()
export class SubACanDeactivateGuard implements CanDeactivate<SubAComponent> {
    public canDeactivate(
        component: SubAComponent,
        _route: ActivatedRouteSnapshot,
        _state: RouterStateSnapshot
    ): boolean {
        console.log('SubACanDeactivateGuard: ', component);
        return true;
    }
}

import { NgModule } from '@angular/core';
import { Routes, RouterModule } from '@angular/router';
import { SubAComponent } from './sub-a.component';
import { SubACanDeactivateGuard } from './sub-a-can-deactivate.guard';

const routes: Routes = [
    { path: '', component: SubAComponent, canDeactivate: [SubACanDeactivateGuard]  }
];

@NgModule({
    imports: [RouterModule.forChild(routes)],
    declarations: [SubAComponent],
    providers: [SubACanDeactivateGuard]
})
export class SubAModule {}