Repositorio del curso CCOM4030 el semestre B91 del proyecto Artesanías con el Instituto de Cultura

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  1. import { Observable } from '../Observable';
  2. import { ObservedValueOf, ObservableInput } from '../types';
  3. /**
  4. * Creates an Observable that, on subscribe, calls an Observable factory to
  5. * make an Observable for each new Observer.
  6. *
  7. * <span class="informal">Creates the Observable lazily, that is, only when it
  8. * is subscribed.
  9. * </span>
  10. *
  11. * ![](defer.png)
  12. *
  13. * `defer` allows you to create the Observable only when the Observer
  14. * subscribes, and create a fresh Observable for each Observer. It waits until
  15. * an Observer subscribes to it, and then it generates an Observable,
  16. * typically with an Observable factory function. It does this afresh for each
  17. * subscriber, so although each subscriber may think it is subscribing to the
  18. * same Observable, in fact each subscriber gets its own individual
  19. * Observable.
  20. *
  21. * ## Example
  22. * ### Subscribe to either an Observable of clicks or an Observable of interval, at random
  23. * ```ts
  24. * import { defer, fromEvent, interval } from 'rxjs';
  25. *
  26. * const clicksOrInterval = defer(function () {
  27. * return Math.random() > 0.5
  28. * ? fromEvent(document, 'click')
  29. * : interval(1000);
  30. * });
  31. * clicksOrInterval.subscribe(x => console.log(x));
  32. *
  33. * // Results in the following behavior:
  34. * // If the result of Math.random() is greater than 0.5 it will listen
  35. * // for clicks anywhere on the "document"; when document is clicked it
  36. * // will log a MouseEvent object to the console. If the result is less
  37. * // than 0.5 it will emit ascending numbers, one every second(1000ms).
  38. * ```
  39. *
  40. * @see {@link Observable}
  41. *
  42. * @param {function(): SubscribableOrPromise} observableFactory The Observable
  43. * factory function to invoke for each Observer that subscribes to the output
  44. * Observable. May also return a Promise, which will be converted on the fly
  45. * to an Observable.
  46. * @return {Observable} An Observable whose Observers' subscriptions trigger
  47. * an invocation of the given Observable factory function.
  48. * @static true
  49. * @name defer
  50. * @owner Observable
  51. */
  52. export declare function defer<R extends ObservableInput<any> | void>(observableFactory: () => R): Observable<ObservedValueOf<R>>;