This library provides useful Modules and Utilities to simplify and enhance efficiency working with Angular Universal

Prerequisites

Angular Universal Version >= 15.0.0

Installation

npm i @nxarch/nguniversal
yarn add @nxarch/nguniversal

TransferStateService

This utility service simplifies working with Angular Universals Transfer State. The service will determine if the provided callback function should be executed based on the existence of the key.

• the TransferStateService methods are called on the server and on the client
• values that are returned by the callback function are stored in the transfer state
• the state is stored as json inside the html that is being sent to the client
• on the client the transferStateService can determine if the value is already present or not based on the key
• once a value is read the key value pair will be removed from the transfer state

Setup

This setup is not required for Angular 14. You can just use the service in your dependency injection.

// browser.module.ts
@NgModule({
  imports: [
    BrowserModule.withServerTransition({ appId: 'ssrApp' }),
    BrowserTransferStateModule, // add this module
  ],
})
export class AppBrowserModule {}

// ssr.module.ts
@NgModule({
  imports: [
    ServerModule,
    AppBrowserModule,
    ServerTransferStateModule, // add this module
  ],
})
export class AppSsrModule {}

Usage

The http call will be made on the server and send to the client with the html.

{ "your-token": "some hello message" }

On the client the transfer state is read. The key "your-token" exists so the callback function won't be executed.

export class AppComponent {
  hello$ = this.transferStateService.fetch('your-token', () =>
    this.http.get<string>('http://localhost:4200/api/hello')
  );

  constructor(
    private readonly transferStateService: TransferStateService,
    private http: HttpClient
  ) {}
}

Environment Tokens

Usage

In terms of environment there are only two states. The statements are run on the server (IS_SERVER) or on the client (IS_BROWSER).

export class AppComponent implements OnInit {
  constructor(
    @Inject(IS_SERVER) private isServer: boolean,
    @Inject(IS_BROWSER) private isBrowser: boolean
  ) {}

  ngOnInit() {
    if (this.isServer) {
      // this will only run on the server
    }
    if (this.isBrowser) {
      // this will only run oin the client
    }
  }
}