`Promise.race()` breaks debugging about ky HOT 7 CLOSED

Promises are supposed to be immutable. Once they are resolved or rejected, they stay that way. That's fundamentally why the Promise.race() approach works. Seems to me like this is a bug in Chrome DevTools, or at least a debugging feature that shouldn't be on by default.

To make sure I'm 100% understanding correctly, though, a reproducible snippet might be useful.

Speaking for myself, I'm open to the idea of short-circuiting the timeout throw if the request already succeeded. It's pretty easy to do and if it aids debugging, seems worth it. Network calls are hard enough to debug as it is, just generally, unrelated to Ky.

from ky.

I've reproduced the issue with this piece of code:

const delay = ms => new Promise(resolve => setTimeout(resolve), ms);

const fn = async () => {
	await delay(100);
	throw new Error('Hello there.');
};

Promise.race([fn(), 'd']);

Indeed, it pauses on these exceptions. Seems like a bug in Chrome.

from ky.

Thanks everyone!

from ky.

Someone should open a Chromium issue → https://chromiumbugs.appspot.com/?token=wrdLx4uRUNV9omU7L9nyKToxNTM5MjE2MDAw&role=&continue=https%3A//bugs.chromium.org/p/chromium/issues/entry.do

from ky.

I am quite sure that this is not a Chrome issue, as it behaves the same way in Firefox, and it’s also logical behavior. When a asynchronous operation is started it shouldn’t be cancelled just because the resulting promise was given as a parameter to Promise.race.

Code to reproduce in Firefox:

const script = document.createElement('script')
script.src = 'https://cdn.jsdelivr.net/npm/[email protected]/umd.js'
document.head.appendChild(script)
// after a delay...
ky.default('/').then(console.log)

The proper fix would be to set some flag to true on successful response and to check the value of this flag before proceeding with TimeoutError.

from ky.

It's a strange behavior for the browser DevTools to have because the Promise is not rejected. Promise.race() effectively acts like a catch () {} in this case. I can imagine some scenarios where it might be nice to inspect Promise races and see all errors in case they were accidentally ignored, but by default the DevTools should probably not break in this case because the Promise is successfully resolved.

from ky.

You are right and actually browser developers agree with you: by default this feature is not activated. And indeed we developers use it sometimes to detect all errors, including those that were accidentally or willingly ignored.

However it is nice not to have such false positives, and Szymon has already suggested a nice solution in my PR #122.

from ky.