Introduce side-effects on error/complete

[xareelee]

I found that tap only supports next event of the streams.

How do I introduce side-effects on error/complete events?

[briancavalier]

Hi @xareelee. Error and end can be observed (and thus perform side-effects) via the promise returned by observe, drain, or reduce.

import { throwError, empty } from 'most'

const s1 = throwError(new Error('error stream'))

s1.drain()
 .catch(e => console.error('errored', e.stack))

const s2 = empty()

s1.drain()
 .then(() => console.log('ended'))

You can also use continueWith and recoverWith to replace the end and error signals with more events.

[xareelee]

@briancavalier

It seems that I can't introduce side-effects for error/complete like tap per subscription. doesn't it?

[Sinewyk]

If you can tap your stream stream, you can continueWith/recoverWith just before subscribing to it.