how to use the notfounderror function from the rxjs library in typescript

To use the NotFoundError function from the rxjs library in TypeScript, you first need to import it from the library.

index.ts
import { NotFoundError } from 'rxjs';
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After importing the function, you can use it in your code wherever you want to throw a NotFoundError error. For example, if you're working with an HTTP request that throws a 404 error, you can use the NotFoundError function to handle it.

index.ts
import { NotFoundError } from 'rxjs';
import { HttpClient } from '@angular/common/http';
import { catchError } from 'rxjs/operators';

const url = 'https://example.com/api/data';

@Injectable()
export class DataService {
  constructor(private http: HttpClient) { }

  getData() {
    return this.http.get(url).pipe(
      catchError(err => {
        if (err.status === 404) {
          return throwError(new NotFoundError('Data not found'));
        }
        return throwError('Error: ' + err.message);
      })
    );
  }
}
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In the example above, the getData function sends a GET request to https://example.com/api/data and catches any errors using the catchError operator. If the HTTP response status is 404, it returns a new NotFoundError error with a custom message. This error can then be handled by the calling code using a try-catch block or by subscribing to the returned observable and handling the error in the error callback.