Question: Best practice for Ajax Progress

[Brooooooklyn]

I was tried to implement a progress subscriber here:
https://github.com/Brooooooklyn/learning-rxjs/blob/article3/src/FileUploader.ts#L171

but it seems not so elegant， and I've tried such things:

const host = `${apiHost}/upload/chunk/${meta.fileKey}?chunk=${index + 1}&chunks=${meta.chunks}`
const subscriber = new Subscriber()
return Observable.ajax({
  url: host,
  body: blob,
  method: 'post',
  crossDomain: true,
  headers: { 'Content-Type': 'application/octet-stream' },
  progressSubscriber: subscriber
})
  .takeUntil(this.pause$)
  .repeatWhen(() => this.resume$)

But can not repeat subscriber when Error occurred.

[trxcllnt]

@Brooooooklyn You should be able to retry by multicasting progress events through a Subject. This is clever, but should do the job:

Observable.never().multicast(
    () => new Subject(),
    (subject) => subject
        .map((data) => ({ type: 'xhr-progress', data }))
        .merge(Observable.ajax({
            /* etc. */
            progressSubscriber: subject
        })
        .map((data) => ({ type: 'xhr-response', data })))
  )
  .takeUntil(this.pause$)
  .repeatWhen(() => this.resume$)