RxJS/Observable logging before `subscribe()`

LogObservable.js

/**
 * Simple logging on an observable, without altering the subscription.
 *
 * @param {Observable<any>} obs - Observable (RxJS)
 * @param success - success message
 * @param failure - error message
 * @returns {Observable<any>}
 */
function logObservable (obs, success, failure) {
  if (success) {
    obs = obs.map(value => {
      console.log(success)
      return value
    })
  }
  if (failure) {
    obs = obs.catch(err => {
      console.error(failure, err)
      throw err
    })
  }
  return obs
}

/** USAGE */
const request = HTTP.get('http://my.domain/path')
logObservable(request, 'GET successful', 'GET Error:')
request.subscribe(value => console.log('GOT:', value))