39 lines
1.7 KiB
TypeScript
39 lines
1.7 KiB
TypeScript
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import { Observable } from '../Observable';
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/**
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* Emits only the last `count` values emitted by the source Observable.
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*
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* <span class="informal">Remembers the latest `count` values, then emits those
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* only when the source completes.</span>
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*
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* <img src="./img/takeLast.png" width="100%">
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*
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* `takeLast` returns an Observable that emits at most the last `count` values
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* emitted by the source Observable. If the source emits fewer than `count`
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* values then all of its values are emitted. This operator must wait until the
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* `complete` notification emission from the source in order to emit the `next`
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* values on the output Observable, because otherwise it is impossible to know
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* whether or not more values will be emitted on the source. For this reason,
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* all values are emitted synchronously, followed by the complete notification.
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*
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* @example <caption>Take the last 3 values of an Observable with many values</caption>
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* var many = Rx.Observable.range(1, 100);
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* var lastThree = many.takeLast(3);
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* lastThree.subscribe(x => console.log(x));
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*
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* @see {@link take}
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* @see {@link takeUntil}
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* @see {@link takeWhile}
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* @see {@link skip}
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*
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* @throws {ArgumentOutOfRangeError} When using `takeLast(i)`, it delivers an
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* ArgumentOutOrRangeError to the Observer's `error` callback if `i < 0`.
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*
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* @param {number} count The maximum number of values to emit from the end of
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* the sequence of values emitted by the source Observable.
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* @return {Observable<T>} An Observable that emits at most the last count
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* values emitted by the source Observable.
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* @method takeLast
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* @owner Observable
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*/
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export declare function takeLast<T>(this: Observable<T>, count: number): Observable<T>;
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