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

71 lines
3.5 KiB
JavaScript

import { async } from '../scheduler/async';
import { timeout as higherOrder } from '../operators/timeout';
/**
*
* Errors if Observable does not emit a value in given time span.
*
* <span class="informal">Timeouts on Observable that doesn't emit values fast enough.</span>
*
* <img src="./img/timeout.png" width="100%">
*
* `timeout` operator accepts as an argument either a number or a Date.
*
* If number was provided, it returns an Observable that behaves like a source
* Observable, unless there is a period of time where there is no value emitted.
* So if you provide `100` as argument and first value comes after 50ms from
* the moment of subscription, this value will be simply re-emitted by the resulting
* Observable. If however after that 100ms passes without a second value being emitted,
* stream will end with an error and source Observable will be unsubscribed.
* These checks are performed throughout whole lifecycle of Observable - from the moment
* it was subscribed to, until it completes or errors itself. Thus every value must be
* emitted within specified period since previous value.
*
* If provided argument was Date, returned Observable behaves differently. It throws
* if Observable did not complete before provided Date. This means that periods between
* emission of particular values do not matter in this case. If Observable did not complete
* before provided Date, source Observable will be unsubscribed. Other than that, resulting
* stream behaves just as source Observable.
*
* `timeout` accepts also a Scheduler as a second parameter. It is used to schedule moment (or moments)
* when returned Observable will check if source stream emitted value or completed.
*
* @example <caption>Check if ticks are emitted within certain timespan</caption>
* const seconds = Rx.Observable.interval(1000);
*
* seconds.timeout(1100) // Let's use bigger timespan to be safe,
* // since `interval` might fire a bit later then scheduled.
* .subscribe(
* value => console.log(value), // Will emit numbers just as regular `interval` would.
* err => console.log(err) // Will never be called.
* );
*
* seconds.timeout(900).subscribe(
* value => console.log(value), // Will never be called.
* err => console.log(err) // Will emit error before even first value is emitted,
* // since it did not arrive within 900ms period.
* );
*
* @example <caption>Use Date to check if Observable completed</caption>
* const seconds = Rx.Observable.interval(1000);
*
* seconds.timeout(new Date("December 17, 2020 03:24:00"))
* .subscribe(
* value => console.log(value), // Will emit values as regular `interval` would
* // until December 17, 2020 at 03:24:00.
* err => console.log(err) // On December 17, 2020 at 03:24:00 it will emit an error,
* // since Observable did not complete by then.
* );
*
* @see {@link timeoutWith}
*
* @param {number|Date} due Number specifying period within which Observable must emit values
* or Date specifying before when Observable should complete
* @param {Scheduler} [scheduler] Scheduler controlling when timeout checks occur.
* @return {Observable<T>} Observable that mirrors behaviour of source, unless timeout checks fail.
* @method timeout
* @owner Observable
*/
export function timeout(due, scheduler = async) {
return higherOrder(due, scheduler)(this);
}
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