Ky: Add upload progress callback

[psixdev]

Hello, I would like to add an image loading indicator. Is this possible when using this library?

[sholladay]

Did you try the onDownloadProgress callback?

[psixdev]

Sorry, it seems I did not ask the question correctly. I need upload progress, not download progress. And onDownloadProgress doesn't help me.

[sholladay]

I see. We don't have that feature at the moment, but it would be nice to add. I think it could be done similarly to download progress.

[Qix-]

It cannot. ky uses fetch under the hood, which uses streams, which does not support upload progress callbacks.

Seems like a pretty bizarre thing to leave out of the spec, if you ask me. Until they're added, ky cannot support them unless it falls back to XMLHttpRequest.

[sholladay]

I realize that fetch doesn't have a callback for upload progress, which is a shame. But I think we should be able to detect when options.body is a stream and then send it through a passthrough stream of our own that reads the chunks manually, similarly to how our onDownloadProgress option works.

[Qix-]

As long as we can determine the total bytes to be uploaded then absolutely :)

[sholladay]

I suppose if the body is just a plain stream, we'd only be able to provide how many bytes have been uploaded but not the total bytes, which may not be super useful.

However, if the body is a Blob or a File (or anything that can be normalized to one of those), then we can use blob.size to get the total bytes. And then we can use blob.stream() to get a ReadableStream for it.

[aldipower]

Really missing this for File uploads. You possible solution sound great @sholladay .