Reactive forms
Reactive forms use a declarative and explicit approach to creating and manipulating form data. Let’s put this concept into practice by creating a new form for our project.
First, on the command line, let’s use the Angular CLI to generate the new component:
ng g c diary/new-entry-form-reactive
In the same way as we did with the template-driven form, let’s add this new component to the DiaryRoutingModule routing module:
import { NewEntryFormReactiveComponent } from './new-entry-form-reactive/new-entry-form-reactive.component';
const routes: Routes = [
  {
    path: '',
    component: DiaryComponent,
  },
  {
    path: 'new-template',
    component: NewEntryFormTemplateComponent,
  },
  {
    path: 'new-reactive',
    component: NewEntryFormReactiveComponent...
