biobulkbende.org/node_modules/rxjs/_esm2015/operator/timeoutWith.js
2020-09-16 14:23:28 +02:00

54 lines
2.9 KiB
JavaScript

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