JavaScript Promises from the Ground Up(joshwcomeau.com)

44 pointsby thunderbong2 anni fa5 comments

https://www.joshwcomeau.com/javascript/promises/

5 comments

Very well-written and easy to follow, wish I had read this a couple years ago :)

I would love a follow-up that fills the gap about the relatio ship between generator functions and promises though.

This part seems very transparent in practise, but I think they're also the reason why the article gets slightly fuzzy at the end.

It claims that 99% of developers need not to care about promise "unwrapping".

But isn't that what powers every async function with more than one "await" in it?

Would also love to read a thorough breakdown of immediately resolved promises and their duality with setTimeout(resolve, 0).

etse2 anni fa

Agreed. This is very well written.

I discovered the joy of Go from dealing with JavaScript promises while writing an API service in Node. So many painful runtime errors uncaught or unlogged because promises don’t (or didn’t) require the catch callback.

I think inverting the programming perspective to default to sync instead of async is more productive for web services development, than perhaps for UI.

gabrielsroka2 anni fa

See my comment above and also

https://news.ycombinator.com/item?id=40825220

And

https://news.ycombinator.com/item?id=40240905

gabrielsroka2 anni fa

> the await keyword is syntactic sugar for the .then() callback:

async/await is not just syntactic sugar. See

https://news.ycombinator.com/item?id=23701736

And the rest of thread

rauschma2 anni fa

It depends on what you mean by syntactic sugar. I follow this definition: https://en.wikipedia.org/wiki/Syntactic_sugar

You can indeed translate an async function to an equivalent function that uses .then() but it’s a radical change, not syntactic sugar (as I use that term).