Implementing Standalone Components in Angular 15

#angular #webdev #tutorial

In this article, I'm going to show you the most important parts to create an angular app using only standalone components. Yes, no ngmodule is needed.

You have all the code available in this repo, which tries to represent a real-world app. If you are learning Angular, give it a try, and give me your thoughts!

DEMO HERE: https://angular-example-app.onrender.com/

1 - Bootstrap

The most important change is inside the src/main.ts file. First of all, we need to bootstrap the application in a different way:

Before:

platformBrowserDynamic().bootstrapModule(AppModule);

After:

import { importProvidersFrom } from '@angular/core';
import { bootstrapApplication } from '@angular/platform-browser';
import { provideRouter } from '@angular/router';
...

bootstrapApplication(AppComponent, {
  providers: [
    importProvidersFrom(HttpClientModule),
    provideRouter([
      {
        path: '',
        component: HomePageComponent,
        pathMatch: 'full',
      },
      { path: '404', component: Error404PageComponent },
      { path: '**', redirectTo: '404' },
    ]),
    ...
  ],
});

Now, we are using provideRouter and importProvidersFrom. These methods allow us to provide routes and extract providers from some modules without importing them.

2 - App Component, but standalone

Following the bootstrap configuration, we need to create components and enable the standalone flag. The app.component.ts looks like this:

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.scss'],
  imports: [RouterOutlet, NgIf, ...],
  standalone: true,
})
export class AppComponent implements OnInit {}

Notice how can we import other standalone components directly, and even other ngmodules, like for example ReactiveFormsModule. Other than that, everything inside the component works as before.
Here another example of component using other standalone components and modules:

@Component({
  selector: 'app-edit-profile',
  templateUrl: './edit-profile.component.html',
  standalone: true,
  imports: [ReactiveFormsModule, TrimDirective, FormErrorsComponent, LowercaseDirective, NgIf],
})
export class EditProfileComponent implements OnInit {}

3 - Lazy loading routes

Lastly, I'm going to show you how to lazy loading routes. You have to do it while defining the bootstrap:

{
  path: 'auth',
    loadChildren: () => import('./app/modules/auth/auth.routes').then(mod => mod.AUTH_ROUTES),
}

Here I'm using a constant called AUTH_ROUTES to hold my auth routes:

export const authPaths = {
  base: 'auth',
  logIn: 'log-in',
  register: 'register',
  logout: 'logout',
};

export const authRoutes = {
  logIn: `/${authPaths.base}/${authPaths.logIn}`,
  register: `/${authPaths.base}/${authPaths.register}`,
  logout: `/${authPaths.base}/${authPaths.logout}`,
};

export const AUTH_ROUTES: Route[] = [
  { path: authPaths.logIn, component: LogInPageComponent, canActivate: [NoAuthGuard] },
  { path: authPaths.register, component: RegisterPageComponent, canActivate: [NoAuthGuard] },
  {
    path: authPaths.logout,
    component: LogoutPageComponent,
  },
  { path: '**', redirectTo: appPaths.error404 },
];