rx-polling is a tiny (1KB gzipped) RxJSv6-based library to run polling requests on intervals, with support for:
- pause and resume if the browser tab is inactive/active
- N retry attempts if the request errors
- Different backoff strategies if the request errors:
- exponential: it will wait 2, 4, ... 64, 256 seconds between attempts. (Default)
- random: it will wait a random time amount between attempts.
- consecutive: it will wait a constant time amount between attempts.
- Observables: it accepts any Observable as input and it returns an Observable, which means it can be combined with other Observables as any other RxJS stream.
- If you need to support rxjs of version <= 5.4 you must install v0.2.3 of rx-polling.
A demo of the library is available at jiayihu.github.io/rx-polling/demo.
npm install rx-polling --save
Fetch data from the endpoint every 5 seconds.
;;;// Example of an Observable which requests some JSON data and completesconst request$ =;;
rx-polling returns an Observable, you can just
.unsubscribe from it to close the polling.
// As previous example but without importsconst request$ =;let subscription =;window;
Combining the polling
You can use the returned
Observable as with any other stream. The sky is the only limit.
// `this.http.get` returns an Observable, like Angular HttpClient classconst request$ = thishttp;let subscription =;
polling(request$, options): Observable
;.../*** Actually any Observable is okay, even if it does not make network requests,* but it must complete at some point otherwise it will never be repeated.*/const request$ = thishttp;const options = interval: 5000 ;;
- emits each value emitted by
request$Observable, resubscribed every
- errors if
request$throws AND if after N attempts it still fails. If any of the attempts succeeds then the polling is recovered and no error is thrown
- completes Never. Be sure to
.unsubscribe()the Observable when you're not anymore interested in the polling.
Options and backoff strategies
rx-polling supports 3 different strategies for delayed attempts on source$ error.
Contributions are welcome. New commits/Pull Requests must:
Have no linter issues. Run
lintscript before committing/pushing.
Have tests passing. Run
testscript before committing/pushing.
@NOTE: testing RxJS is currently really hard. This repo uses Jest contains some custom utilities to improve testing and error reports. The following console output is not standard and totally custom, so be aware of possible issues.
Nevertheless marbles are awesome! You can read more about it in Testing Observables in RxJS6