Callbags and Canceling with CAF

index.js

require('regenerator-runtime/runtime')

import { forEach, map, pipe, fromEvent, scan } from 'callbag-basics'
import CAF from 'caf'

let source = pipe(
  fromEvent(document, 'keydown'),
  map(event => function * (signal) {
    console.log('%cbegin', 'color:red')
    yield CAF.delay(signal, 1000)
    console.log('%cend', 'color:green')
    return 'complete!'
  }),
  scan((coll, fn) => {
    if (coll.token) coll.token.abort('cancel')
    coll.token = new CAF.cancelToken()
    return { token: coll.token, fn }
  }, {}),
  map(({ token, fn }) => 
    CAF(fn)(token.signal)
  )
)

forEach(p =>p
  .then(result => console.log(result))
  .catch(canceled => console.log(canceled))
)(source)