Inconsistent behaviour of isAsyncIterable function between Chrome and Firefox

[negamaxi]

This code works in Firefox 115.0 and throws error in Chrome 114.0:

const fileObject = Array.from(files).map((file) => ({
  path: file.name,
  content: file.stream(),
}));

for await (const cid of heliaFS.addAll(fileObject)) {
  console.log(cid);
}

The reason is in this function:

js-ipfs-unixfs/packages/ipfs-unixfs-importer/src/dag-builder/index.ts

Lines 37 to 39 in 4721879

	function isAsyncIterable (thing: any): thing is AsyncIterable<any> {
	return Symbol.asyncIterator in thing
	}

It returns true in Firefox and false in Chrome for file.stream() result (instance of ReadableStream) passed as value of fileObject.content:

[achingbrain]

This is annoying but also expected - please see the browser compatibility table on MDN - https://developer.mozilla.org/en-US/docs/Web/API/ReadableStream#browser_compatibility

Only node.js, deno and Firefox support iterating over ReadableStreams as AsyncIterators.

The relevant Chromium bug is here.