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

The defaultIfEmpty operator from the RxJS library is used to emit a default value if an observable sequence completes without emitting any values.

Here's an example of how to use it:

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

const example$ = of().pipe(defaultIfEmpty('No values emitted'));
example$.subscribe(value => console.log(value));
// Output: 'No values emitted'
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In this example, we start with an empty observable sequence using the of() function. We then pipe in the defaultIfEmpty operator and provide a default value of 'No values emitted'. Finally, we subscribe to the resulting observable and log the emitted value in the console, which in this case is the default value since the original sequence was empty.