How to use WriteStream with api endpoints?

[AhsanSarwar45]

I have a 'stream' function that returns a WriteStream. The usage in express is like this:

const stream = require('youtube-audio-stream');

const uri = "https://www.youtube.com/watch?v=t1TcDHrkQYg";

app.get("/stream", (req, res) => {
  stream(uri).pipe(res);
})

How can I do the equivalent in svelte kit api endpoints? The docs gives example of ReadableStream but not WriteStream.

[karimfromjordan]

If your package only works with Node.js streams and not web streams you likely have to convert between the two using Readable/Writable.fromWeb()/toWeb(). The Response constructor accepts ReadableStreams as the body argument. Make sure to read about Readable.toWeb() in the Node.js docs and GitHub issues because it can consume too much memory if you don't limit it.

// +server.js
import { Readable } from 'node:stream';
import stream from 'youtube-audio-stream';

export function POST(event) {
  const web_rstream = Readable.toWeb(stream(url));
  
  return new Response(web_rstream);
}

It requires at least Node.js 17.0.0.