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  1. import { Observable } from '../Observable';
  2. import { ObservableInput, ObservableInputTuple, SchedulerLike } from '../types';
  3. import { mergeAll } from '../operators/mergeAll';
  4. import { innerFrom } from './innerFrom';
  5. import { EMPTY } from './empty';
  6. import { popNumber, popScheduler } from '../util/args';
  7. import { from } from './from';
  8. export function merge<A extends readonly unknown[]>(...sources: [...ObservableInputTuple<A>]): Observable<A[number]>;
  9. export function merge<A extends readonly unknown[]>(...sourcesAndConcurrency: [...ObservableInputTuple<A>, number?]): Observable<A[number]>;
  10. /** @deprecated The `scheduler` parameter will be removed in v8. Use `scheduled` and `mergeAll`. Details: https://rxjs.dev/deprecations/scheduler-argument */
  11. export function merge<A extends readonly unknown[]>(
  12. ...sourcesAndScheduler: [...ObservableInputTuple<A>, SchedulerLike?]
  13. ): Observable<A[number]>;
  14. /** @deprecated The `scheduler` parameter will be removed in v8. Use `scheduled` and `mergeAll`. Details: https://rxjs.dev/deprecations/scheduler-argument */
  15. export function merge<A extends readonly unknown[]>(
  16. ...sourcesAndConcurrencyAndScheduler: [...ObservableInputTuple<A>, number?, SchedulerLike?]
  17. ): Observable<A[number]>;
  18. /**
  19. * Creates an output Observable which concurrently emits all values from every
  20. * given input Observable.
  21. *
  22. * <span class="informal">Flattens multiple Observables together by blending
  23. * their values into one Observable.</span>
  24. *
  25. * ![](merge.png)
  26. *
  27. * `merge` subscribes to each given input Observable (as arguments), and simply
  28. * forwards (without doing any transformation) all the values from all the input
  29. * Observables to the output Observable. The output Observable only completes
  30. * once all input Observables have completed. Any error delivered by an input
  31. * Observable will be immediately emitted on the output Observable.
  32. *
  33. * ## Examples
  34. *
  35. * Merge together two Observables: 1s interval and clicks
  36. *
  37. * ```ts
  38. * import { merge, fromEvent, interval } from 'rxjs';
  39. *
  40. * const clicks = fromEvent(document, 'click');
  41. * const timer = interval(1000);
  42. * const clicksOrTimer = merge(clicks, timer);
  43. * clicksOrTimer.subscribe(x => console.log(x));
  44. *
  45. * // Results in the following:
  46. * // timer will emit ascending values, one every second(1000ms) to console
  47. * // clicks logs MouseEvents to console every time the "document" is clicked
  48. * // Since the two streams are merged you see these happening
  49. * // as they occur.
  50. * ```
  51. *
  52. * Merge together 3 Observables, but run only 2 concurrently
  53. *
  54. * ```ts
  55. * import { interval, take, merge } from 'rxjs';
  56. *
  57. * const timer1 = interval(1000).pipe(take(10));
  58. * const timer2 = interval(2000).pipe(take(6));
  59. * const timer3 = interval(500).pipe(take(10));
  60. *
  61. * const concurrent = 2; // the argument
  62. * const merged = merge(timer1, timer2, timer3, concurrent);
  63. * merged.subscribe(x => console.log(x));
  64. *
  65. * // Results in the following:
  66. * // - First timer1 and timer2 will run concurrently
  67. * // - timer1 will emit a value every 1000ms for 10 iterations
  68. * // - timer2 will emit a value every 2000ms for 6 iterations
  69. * // - after timer1 hits its max iteration, timer2 will
  70. * // continue, and timer3 will start to run concurrently with timer2
  71. * // - when timer2 hits its max iteration it terminates, and
  72. * // timer3 will continue to emit a value every 500ms until it is complete
  73. * ```
  74. *
  75. * @see {@link mergeAll}
  76. * @see {@link mergeMap}
  77. * @see {@link mergeMapTo}
  78. * @see {@link mergeScan}
  79. *
  80. * @param args `ObservableInput`s to merge together. If the last parameter
  81. * is of type number, `merge` will use it to limit number of concurrently
  82. * subscribed `ObservableInput`s. If the last parameter is {@link SchedulerLike},
  83. * it will be used for scheduling the emission of values.
  84. * @return An Observable that emits items that are the result of every input Observable.
  85. */
  86. export function merge(...args: (ObservableInput<unknown> | number | SchedulerLike)[]): Observable<unknown> {
  87. const scheduler = popScheduler(args);
  88. const concurrent = popNumber(args, Infinity);
  89. const sources = args as ObservableInput<unknown>[];
  90. return !sources.length
  91. ? // No source provided
  92. EMPTY
  93. : sources.length === 1
  94. ? // One source? Just return it.
  95. innerFrom(sources[0])
  96. : // Merge all sources
  97. mergeAll(concurrent)(from(sources, scheduler));
  98. }