`Cannot abort a stream that already has a writer`

Hi, thanks for this great polyfill first.

I want to close the WritableStream when the user cancels the download process, but it throws as title, is there any solution?

I’m using the hacky way currently.

if (evt.data.aborted) {
  if (stream._writer) {
    stream._writer.abort()
    stream._writer = undefined
  }
  stream.abort()
}

[MattiasBuelens]

So basically you’ve built your own version of ReadableStream.pipeTo() outside of this polyfill. The problem is that your version doesn’t implement all of the requirements for pipeTo, specifically these:

• Errors must be propagated forward: if source is or becomes errored, then abort the destination.
• Errors must be propagated backward: if destination is or becomes errored, then cancel the source.

This polyfill does implement these requirements, see the source.

May I suggest a different approach? Instead of building a separate version of pipeTo that works with Firefox’s native streams, adapt the native stream into a polyfill stream first using e.g. web-streams-adapter. Then you can use the full API of the polyfill again, including pipeTo. 😉

EDIT: Forget to mention, it’s published as @mattiasbuelens/web-streams-adapter.

[shakamd]

@JounQin, curious to see if you are able to solve this. I’m also trying to support user download cancellation in my app with streamsaver.