54 lines
2.9 KiB
JavaScript
54 lines
2.9 KiB
JavaScript
import { async } from '../scheduler/async';
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import { timeoutWith as higherOrder } from '../operators/timeoutWith';
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/* tslint:enable:max-line-length */
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/**
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*
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* Errors if Observable does not emit a value in given time span, in case of which
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* subscribes to the second Observable.
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*
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* <span class="informal">It's a version of `timeout` operator that let's you specify fallback Observable.</span>
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*
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* <img src="./img/timeoutWith.png" width="100%">
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*
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* `timeoutWith` is a variation of `timeout` operator. It behaves exactly the same,
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* still accepting as a first argument either a number or a Date, which control - respectively -
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* when values of source Observable should be emitted or when it should complete.
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*
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* The only difference is that it accepts a second, required parameter. This parameter
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* should be an Observable which will be subscribed when source Observable fails any timeout check.
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* So whenever regular `timeout` would emit an error, `timeoutWith` will instead start re-emitting
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* values from second Observable. Note that this fallback Observable is not checked for timeouts
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* itself, so it can emit values and complete at arbitrary points in time. From the moment of a second
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* subscription, Observable returned from `timeoutWith` simply mirrors fallback stream. When that
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* stream completes, it completes as well.
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*
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* Scheduler, which in case of `timeout` is provided as as second argument, can be still provided
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* here - as a third, optional parameter. It still is used to schedule timeout checks and -
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* as a consequence - when second Observable will be subscribed, since subscription happens
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* immediately after failing check.
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*
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* @example <caption>Add fallback observable</caption>
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* const seconds = Rx.Observable.interval(1000);
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* const minutes = Rx.Observable.interval(60 * 1000);
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*
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* seconds.timeoutWith(900, minutes)
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* .subscribe(
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* value => console.log(value), // After 900ms, will start emitting `minutes`,
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* // since first value of `seconds` will not arrive fast enough.
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* err => console.log(err) // Would be called after 900ms in case of `timeout`,
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* // but here will never be called.
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* );
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*
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* @param {number|Date} due Number specifying period within which Observable must emit values
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* or Date specifying before when Observable should complete
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* @param {Observable<T>} withObservable Observable which will be subscribed if source fails timeout check.
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* @param {Scheduler} [scheduler] Scheduler controlling when timeout checks occur.
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* @return {Observable<T>} Observable that mirrors behaviour of source or, when timeout check fails, of an Observable
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* passed as a second parameter.
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* @method timeoutWith
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* @owner Observable
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*/
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export function timeoutWith(due, withObservable, scheduler = async) {
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return higherOrder(due, withObservable, scheduler)(this);
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}
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//# sourceMappingURL=timeoutWith.js.map
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