body.getReader() method missing (node 14.x)

[jasonswearingen]

There seems to be a problem using web-streams-polyfill on nodejs 14.x

I ran into the issue where, given some code like described in the documentation:

const ky = require('ky-universal');

(async () => {
    const {body} = await ky('https://httpbin.org/bytes/16');
    const {value} = await body.getReader().read();
    const result = new TextDecoder('utf-8').decode(value);

    // …
})();

I would get a runtime error:

TypeError: _a.getReader is not a function

at the 'body.getReader() call.

I read the docs to install web-streams-polyfill which I did (3.0.0) but still get the error.

I took stepped through the ky-universal code and see

//index.js
if (!global.ReadableStream) {
    try {
        global.ReadableStream = require('web-streams-polyfill/ponyfill/es2018');
    } catch (_) {}
}

This seems to be a problem because the require('web-streams-polyfill/ponyfill/es2018') returns an object, so the following fails:

//ky/umd.js
const supportsStreams = typeof globals.ReadableStream === 'function';

so.... clever me, I thought I would pre-shim the globals.ReadableStream to hot-patch the problem by adding this to my app code:

if ( !global.ReadableStream ) {
  global.ReadableStream = require( 'web-streams-polyfill/ponyfill/es2018' ).ReadableStream
}

but still, the body.getReader() function doesn't exist. Unfortunately the ky code is too fancy for me to follow, so here I am, filing this issue!

fyi, I also tried web-streams-polyfill@2.1.1 but same error.

[sholladay]

Indeed, I am able to reproduce this. For some reason, body ends up being a Node PassThrough stream, instead of a web compliant stream, even when web streams have been polyfilled. This is probably an issue with node-fetch rather than Ky or ky-universal. I will leave this open for tracking purposes, though.

[AuHau]

Well if you read node-fetch's Known differences from client documentation it is clearly specified there that they expose Node's Readable stream and not WHATWG's stream, so I don't think this is node-fetch problem but ky-universal...

[sholladay]

It doesn't really make sense for Ky to handle any other stream implementation besides web streams. But I'll agree with you in the sense that it's our fault for assuming that node-fetch would comply, or at least try to comply, with the specification. We're clearly going to have to switch to a better polyfill that properly implements the spec. See: https://github.com/sindresorhus/ky-universal/issues/34

[sindresorhus]

This package is no longer needed if you target Node.js 18 or later: https://github.com/sindresorhus/ky/releases/tag/v1.0.0