This project was generated with Angular CLI version 7.2.1.

ng g c components/first
ng g c components/second

const routes: Routes = [
  { path: 'first', component: FirstComponent },
  { path: 'second', component: SecondComponent }
];

<button type="input" [routerLink]="[ '/first' ]"> first </button>
<button type="input" [routerLink]="[ '/second' ]"> second </button>
<main>
  <router-outlet></router-outlet>
</main>

ng g m components/first --routing
ng g m components/second --routing

const routes: Routes = [
  { path: 'first', loadChildren: './components/first/first.module#FirstModule' },
  { path: 'second', loadChildren: './components/second/second.module#SecondModule' }
];

  import { FirstComponent } from './first.component';

  const routes: Routes = [
    { path: '', component: FirstComponent}
  ];

  import { SecondComponent } from './second.component';

  const routes: Routes = [
    { path: '', component: SecondComponent }
  ];

Note: Declare the components in their respective modules and eliminate the declarations of the components in the main module of the application

ng update @angular/cli @angular/core --allow-dirty

Run ng serve for a dev server. Navigate to http://localhost:4200/. The app will automatically reload if you change any of the source files.

Run ng generate component component-name to generate a new component. You can also use ng generate directive|pipe|service|class|guard|interface|enum|module.

Run ng build to build the project. The build artifacts will be stored in the dist/ directory. Use the --prod flag for a production build.

Run ng test to execute the unit tests via Karma.

Run ng e2e to execute the end-to-end tests via Protractor.

To get more help on the Angular CLI use ng help or go check out the Angular CLI README.