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56 lines
2.1 KiB
56 lines
2.1 KiB
4 years ago
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import { MonoTypeOperatorFunction } from '../types';
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/**
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* Make a {@link ConnectableObservable} behave like a ordinary observable and automates the way
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* you can connect to it.
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*
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* Internally it counts the subscriptions to the observable and subscribes (only once) to the source if
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* the number of subscriptions is larger than 0. If the number of subscriptions is smaller than 1, it
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* unsubscribes from the source. This way you can make sure that everything before the *published*
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* refCount has only a single subscription independently of the number of subscribers to the target
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* observable.
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*
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* Note that using the {@link share} operator is exactly the same as using the *publish* operator
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* (making the observable hot) and the *refCount* operator in a sequence.
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*
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* 
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*
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* ## Example
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*
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* In the following example there are two intervals turned into connectable observables
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* by using the *publish* operator. The first one uses the *refCount* operator, the
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* second one does not use it. You will notice that a connectable observable does nothing
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* until you call its connect function.
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*
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* ```ts
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* import { interval } from 'rxjs';
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* import { tap, publish, refCount } from 'rxjs/operators';
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*
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* // Turn the interval observable into a ConnectableObservable (hot)
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* const refCountInterval = interval(400).pipe(
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* tap((num) => console.log(`refCount ${num}`)),
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* publish(),
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* refCount()
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* );
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*
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* const publishedInterval = interval(400).pipe(
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* tap((num) => console.log(`publish ${num}`)),
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* publish()
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* );
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*
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* refCountInterval.subscribe();
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* refCountInterval.subscribe();
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* // 'refCount 0' -----> 'refCount 1' -----> etc
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* // All subscriptions will receive the same value and the tap (and
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* // every other operator) before the publish operator will be executed
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* // only once per event independently of the number of subscriptions.
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*
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* publishedInterval.subscribe();
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* // Nothing happens until you call .connect() on the observable.
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* ```
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*
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* @see {@link ConnectableObservable}
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* @see {@link share}
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* @see {@link publish}
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*/
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export declare function refCount<T>(): MonoTypeOperatorFunction<T>;
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