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defaultIfEmpty
signature: defaultIfEmpty(defaultValue: any): Observable
defaultIfEmpty(defaultValue: any): ObservableEmit given value if nothing is emitted before completion.
Examples
Example 1: Default for empty value
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// RxJS v6+
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import { defaultIfEmpty } from 'rxjs/operators';
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import { of } from 'rxjs';
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//emit 'Observable.of() Empty!' when empty, else any values from source
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const exampleOne = of().pipe(defaultIfEmpty('Observable.of() Empty!'));
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//output: 'Observable.of() Empty!'
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const subscribe = exampleOne.subscribe(val => console.log(val));
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Example 2: Default for Observable.empty
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// RxJS v6+
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import { defaultIfEmpty } from 'rxjs/operators';
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import { empty } from 'rxjs';
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//emit 'Observable.empty()!' when empty, else any values from source
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const example = empty().pipe(defaultIfEmpty('Observable.empty()!'));
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//output: 'Observable.empty()!'
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const subscribe = example.subscribe(val => console.log(val));
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Additional Resources
- docs
Last modified 2yr ago