never.d.ts 1.1 KB

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  1. import { Observable } from '../Observable';
  2. /**
  3. * An Observable that emits no items to the Observer and never completes.
  4. *
  5. * ![](never.png)
  6. *
  7. * A simple Observable that emits neither values nor errors nor the completion
  8. * notification. It can be used for testing purposes or for composing with other
  9. * Observables. Please note that by never emitting a complete notification, this
  10. * Observable keeps the subscription from being disposed automatically.
  11. * Subscriptions need to be manually disposed.
  12. *
  13. * ## Example
  14. * ### Emit the number 7, then never emit anything else (not even complete)
  15. * ```ts
  16. * import { NEVER } from 'rxjs';
  17. * import { startWith } from 'rxjs/operators';
  18. *
  19. * function info() {
  20. * console.log('Will not be called');
  21. * }
  22. * const result = NEVER.pipe(startWith(7));
  23. * result.subscribe(x => console.log(x), info, info);
  24. *
  25. * ```
  26. *
  27. * @see {@link Observable}
  28. * @see {@link index/EMPTY}
  29. * @see {@link of}
  30. * @see {@link throwError}
  31. */
  32. export declare const NEVER: Observable<never>;
  33. /**
  34. * @deprecated Deprecated in favor of using {@link NEVER} constant.
  35. */
  36. export declare function never(): Observable<never>;