timeout.ts
4.07 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
import { async } from '../scheduler/async';
import { isDate } from '../util/isDate';
import { Operator } from '../Operator';
import { Subscriber } from '../Subscriber';
import { Observable } from '../Observable';
import { TimeoutError } from '../util/TimeoutError';
import { MonoTypeOperatorFunction, SchedulerAction, SchedulerLike, TeardownLogic } from '../types';
import { timeoutWith } from './timeoutWith';
import { throwError } from '../observable/throwError';
/**
*
* 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>
*
* 
*
* `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.
*
* ## Examples
* Check if ticks are emitted within certain timespan
* ```ts
* import { interval } from 'rxjs';
* import { timeout } from 'rxjs/operators';
*
* const seconds = interval(1000);
*
* seconds.pipe(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.pipe(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.
* );
* ```
*
* Use Date to check if Observable completed
* ```ts
* import { interval } from 'rxjs';
* import { timeout } from 'rxjs/operators';
*
* const seconds = interval(1000);
*
* seconds.pipe(
* 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 {SchedulerLike} [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<T>(due: number | Date,
scheduler: SchedulerLike = async): MonoTypeOperatorFunction<T> {
return timeoutWith(due, throwError(new TimeoutError()), scheduler);
}