Not the GP but it could be the length of your sentences. I personally think it reads fine however, since I also write with pretty long, heavily punctuated, sentences I’m comfortable reading it and it feels natural to me. The biggest complaint people have about my writing is the length of the sentences and feeling like I’m expressing too many ideas at a time.
Complementing your answer, I'd also like to point out that another notable guarantee that promises give us is that their continuations are never executed synchronously (even when they could), which prevents the problem described by https://blog.izs.me/2013/08/designing-apis-for-asynchrony/.
It's as @AgentME said, it is just meant as a disclaimer that the project should be installed via the "installer", i.e. `npm create promises-training@latest`, otherwise the project won't work as expected.
But I agree the phrasing is a little bit weird, will review it.
Recently I've created a project to help people deepen their knowledge on Promises in Javascript beyond the basics by working through a series of practical exercises, where each is accompanied by a set of automated tests.
One thing I have recently stumbled upon is that the way Promise.all() is commonly used is "wrong" in the sense that it is prone to uncatchable promise rejections (which cause both Node and Deno to exit the whole process by default).
I would really like to see a tutorial on how to solve this the right way -- right now it seems that everybody does it the "wrong way" and the problem isn't even mentioned.
Common pattern #1 (tuple-style):
const result = await Promise.all([
someAsyncFunction1(computeArg1()),
someAsyncFunction2(computeArg2()),
]);
Common pattern #2 (array-map-style):
const result = await Promise.all(elements.map(x => someAsyncFunction3(computeArg3(x))));
Both suffer from the same problem: If computeArg2 / computeArg3 potentially throw a (synchronous) error, then some promises have already been created, but Promise.all() never runs and so they don't have a catch-handler. If one of those rejects ("throws asynchronously") then that rejection is unhandled and crashes the process.
The answer is to never throw exceptions from promise returning functions. Mark all promise returning functions `async` - even when it doesn't `await` - because an async function always returns.
That one is super interesting. For the first example, I'm not even really sure how I'd expect that to behave, it feels like no matter how it works it becomes slightly inconsistent with my expectations of the language. Like, if it were changed to somehow let a .catch grab the synchronous errors or have it somehow evaluate all of the compute functions synchronously first before making the promises, it still feels wrong. Maybe the only good solution is run the compute args separately beforehand?
For the second example, it's kind of a weird one, but I'm actually a fan of using async .reduce to accomplish that. It took me a minute the first time I saw someone do it, but I think it more cleanly solves the problem and gives you more control over the result.
Reduce can use an async function which wraps the collector in a promise and gives you a ton of control over how it executes because you can choose at what point you want the function to block waiting for previous results.
In this particular case it's a lot more verbose, obviously, but if you're doing any kind of further processing of each element, you can move it into the reduce and be able to control exactly what you get out of it if something fails for any reason, while still running mostly concurrently like all or allSettled would.
const result = await elements.reduce(async (collector, x) => {
const arg3 = computeArg3(x) // explicitly handle whatever errors, try catch, whatever you need
const asyncResult = await someAsyncFunction3(arg3)
// this has to happen after calling someAsyncFunction because it will block until the previous iteration finishes
collector = await collector;
collector.push(result)
return collector
}, []);
allSettled() returns an array of objects for each promise result that tells you if it has been rejected or resolved, so as long as all the promises reject or resolve then it should solve the problem I think?
