Do you know "defaultIfEmpty" operator?
It emits the default value if the source completes without having emitted any value.
It could be helpful in several scenarios.
import { of } from 'rxjs'; import { map, defaultIfEmpty } from 'rxjs/operators'; // source2 doesn't have any values; using defaultIfEmpty, we can have a "default" value. const source1 = of().pipe( defaultIfEmpty('Hello There') ); source1.subscribe(x => console.log(x)); // source1 has a value const source2 = of('Hello World').pipe( defaultIfEmpty('Hello There') ); source2.subscribe(x => console.log(x)); Live Code
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