95ab2b8585b3a8f3b3ed7a1cc0e5d06dd8261799b1f9f41f0d8d00e2da28c78856ea3596dcd1829aba205f6a3282e1b12915be4d2fc0b0bf0bb08d7376ea1e 3.0 KB

12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364
  1. import { switchMap } from './switchMap';
  2. import { ObservableInput, OperatorFunction, ObservedValueOf } from '../types';
  3. import { isFunction } from '../util/isFunction';
  4. /** @deprecated Will be removed in v9. Use {@link switchMap} instead: `switchMap(() => result)` */
  5. export function switchMapTo<O extends ObservableInput<unknown>>(observable: O): OperatorFunction<unknown, ObservedValueOf<O>>;
  6. /** @deprecated The `resultSelector` parameter will be removed in v8. Use an inner `map` instead. Details: https://rxjs.dev/deprecations/resultSelector */
  7. export function switchMapTo<O extends ObservableInput<unknown>>(
  8. observable: O,
  9. resultSelector: undefined
  10. ): OperatorFunction<unknown, ObservedValueOf<O>>;
  11. /** @deprecated The `resultSelector` parameter will be removed in v8. Use an inner `map` instead. Details: https://rxjs.dev/deprecations/resultSelector */
  12. export function switchMapTo<T, R, O extends ObservableInput<unknown>>(
  13. observable: O,
  14. resultSelector: (outerValue: T, innerValue: ObservedValueOf<O>, outerIndex: number, innerIndex: number) => R
  15. ): OperatorFunction<T, R>;
  16. /**
  17. * Projects each source value to the same Observable which is flattened multiple
  18. * times with {@link switchMap} in the output Observable.
  19. *
  20. * <span class="informal">It's like {@link switchMap}, but maps each value
  21. * always to the same inner Observable.</span>
  22. *
  23. * ![](switchMapTo.png)
  24. *
  25. * Maps each source value to the given Observable `innerObservable` regardless
  26. * of the source value, and then flattens those resulting Observables into one
  27. * single Observable, which is the output Observable. The output Observables
  28. * emits values only from the most recently emitted instance of
  29. * `innerObservable`.
  30. *
  31. * ## Example
  32. *
  33. * Restart an interval Observable on every click event
  34. *
  35. * ```ts
  36. * import { fromEvent, switchMapTo, interval } from 'rxjs';
  37. *
  38. * const clicks = fromEvent(document, 'click');
  39. * const result = clicks.pipe(switchMapTo(interval(1000)));
  40. * result.subscribe(x => console.log(x));
  41. * ```
  42. *
  43. * @see {@link concatMapTo}
  44. * @see {@link switchAll}
  45. * @see {@link switchMap}
  46. * @see {@link mergeMapTo}
  47. *
  48. * @param innerObservable An `ObservableInput` to replace each value from the
  49. * source Observable.
  50. * @return A function that returns an Observable that emits items from the
  51. * given `innerObservable` (and optionally transformed through the deprecated
  52. * `resultSelector`) every time a value is emitted on the source Observable,
  53. * and taking only the values from the most recently projected inner
  54. * Observable.
  55. * @deprecated Will be removed in v9. Use {@link switchMap} instead: `switchMap(() => result)`
  56. */
  57. export function switchMapTo<T, R, O extends ObservableInput<unknown>>(
  58. innerObservable: O,
  59. resultSelector?: (outerValue: T, innerValue: ObservedValueOf<O>, outerIndex: number, innerIndex: number) => R
  60. ): OperatorFunction<T, ObservedValueOf<O> | R> {
  61. return isFunction(resultSelector) ? switchMap(() => innerObservable, resultSelector) : switchMap(() => innerObservable);
  62. }