[RxJS] Resubscribing to a Stream with Repeat

When you complete a stream, there’s no way to restart it, you must resubscribe. This lesson shows how repeat comes in handy to resubscribe after a stream has completed.

 

Current this block of code:

const timer$ = starters$
    .switchMap(intervalActions)
    .startWith(data)
    .scan((acc, curr)=> curr(acc))


timer$
    .do((x)=> console.log(x))
    .takeWhile((data)=> data.count <= 3)
    .withLatestFrom(
        input$.do((x)=> console.log(x)),
        (timer, input)=> ({count: timer.count, text: input})
    )
    .filter((data)=> data.count === parseInt(data.text))
    .reduce((acc, curr)=> acc + 1, 0)
    .subscribe(
        (x)=> console.log('Score', x),
        err=> console.log(err),
        ()=> console.log('complete')
    );

/**
"Score"
0
"complete"
**/

 

Once it hit complete block, you can never start the timer again. THis is because the stream is completed, so if we want able to re-subscribe many times, we can use repeact() method:

timer$
    .do((x)=> console.log(x))
    .takeWhile((data)=> data.count <= 3)
    .withLatestFrom(
        input$.do((x)=> console.log(x)),
        (timer, input)=> ({count: timer.count, text: input})
    )
    .filter((data)=> data.count === parseInt(data.text))
    .reduce((acc, curr)=> acc + 1, 0)
    .repeat() // repact the block of code above
    .subscribe(
        (x)=> console.log('Score', x),
        err=> console.log(err),
        ()=> console.log('complete')
    );

Now we are able to repact the stream, but it will never hit the complete block, but it is ok.

 

And also should be careful when use repeact(); you cannot put it anywhere you want, if you put it before fiilter(), then it willl never hit the filter block, so usually should put it right before the subscribe() method.