how to use the throwifempty function from the rxjs library in javascript

To use the throwIfEmpty function from the rxjs library in JavaScript, you'll need to first import it. Here's an example:

index.tsx
import { of } from 'rxjs';
import { throwIfEmpty } from 'rxjs/operators';

of()
  .pipe(throwIfEmpty())
  .subscribe({
    error: (err) => console.error(err),
    complete: () => console.log('Completed'),
  });
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In the example above, the throwIfEmpty function is used as a pipeable operator inside an Observable. If the Observable is empty, it will throw an error with a default message "no elements in sequence".

You can customize the error message by passing a string argument to throwIfEmpty, like this:

index.tsx
import { of } from 'rxjs';
import { throwIfEmpty } from 'rxjs/operators';

of()
  .pipe(throwIfEmpty('Oops, the sequence is empty!'))
  .subscribe({
    error: (err) => console.error(err),
    complete: () => console.log('Completed'),
  });
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Now, if the Observable is empty, it will throw an error with a message "Oops, the sequence is empty!".