16 lines
926 B
TypeScript
16 lines
926 B
TypeScript
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import { Observable } from '../Observable';
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/**
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* Returns an observable of a single number that represents the number of items that either:
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* Match a provided predicate function, _or_ if a predicate is not provided, the number
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* represents the total count of all items in the source observable. The count is emitted
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* by the returned observable when the source observable completes.
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* @param {function} [predicate] a boolean function to select what values are to be counted.
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* it is provided with arguments of:
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* - `value`: the value from the source observable
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* - `index`: the "index" of the value from the source observable
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* - `source`: the source observable instance itself.
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* @returns {Observable} an observable of one number that represents the count as described
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* above
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*/
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export declare function count<T>(predicate?: (value: T, index: number, source: Observable<T>) => boolean): Observable<number>;
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