在Angular Universal中,可以使用TransferState
服务来解决在客户端上不重新填充DOM节点的问题。TransferState
服务允许将数据从服务器传输到客户端,以便客户端应用程序可以直接获取这些数据,而不需要重新获取或重新计算。
下面是一个示例代码,演示如何在Angular Universal中使用TransferState
服务:
app.server.module.ts
文件中,导入TransferState
和ServerTransferStateModule
:import { TransferState } from '@angular/platform-browser';
import { ServerTransferStateModule } from '@angular/platform-server';
// ...
@NgModule({
imports: [
// ...
ServerTransferStateModule
],
providers: [
// ...
TransferState
]
})
export class AppServerModule { }
TransferState
服务将数据传输到客户端。例如,在一个服务中:import { TransferState, makeStateKey } from '@angular/platform-browser';
// ...
@Injectable()
export class DataService {
private dataKey = makeStateKey('data');
constructor(private http: HttpClient, private transferState: TransferState) { }
getData(): Observable {
if (this.transferState.hasKey(this.dataKey)) {
const data = this.transferState.get(this.dataKey, null);
this.transferState.remove(this.dataKey);
return of(data);
} else {
return this.http.get('/api/data').pipe(
tap((data) => {
this.transferState.set(this.dataKey, data);
})
);
}
}
}
TransferState
服务中获取数据,而无需重新获取或重新计算。例如,在一个组件中:import { TransferState, makeStateKey } from '@angular/platform-browser';
// ...
@Component({
// ...
})
export class MyComponent implements OnInit {
private dataKey = makeStateKey('data');
data: any;
constructor(private transferState: TransferState) { }
ngOnInit() {
if (this.transferState.hasKey(this.dataKey)) {
this.data = this.transferState.get(this.dataKey, null);
this.transferState.remove(this.dataKey);
} else {
// Handle case where data is not available on the client side
}
}
}
通过使用TransferState
服务,在服务器端和客户端之间传递数据,可以避免在客户端上重新填充DOM节点,提高应用程序的性能和用户体验。