[davelnewton]

Promises/async/await seem very different than Ruby's (and Rails') metaprogramming to me. I'd need an example of a cryptic stack trace to know exactly what you're referring to--half the problem is because of the overuse of anonymous functions that bork the trace. There's an easy solution to that (and it makes the resulting code easier to test as well).

[weaksauce]

the fact that there is a long chapter in a book series written on the edge cases of javascript[0] leads me to believe that it's not generally well understood either.

0. https://github.com/getify/You-Dont-Know-JS/blob/1st-ed/async...

[horsawlarway]

JS uses an event-loop (which is really just a variation of a message/event queue that we've been using for GUI based applications for decades now). If you understand this, asynchronous code in JS is pretty easy to understand.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Even...

You can go from nothing to mostly full-fledged promises in about 200 lines of code: ex - https://www.promisejs.org/implementing/

async/await is pure sugar on top of promises (it's literally just wrapping the rest of the function in a .then() for you, and coercing the return value of your function to always be a promise)

[davelnewton]

IMO that's an explicitly different issue than a comparison between Promises/async/await and Ruby's metaprogramming, though.

Not to mention that part of the issue with Promises is the various polyfills invented before broad acceptance, which is a separate can of worms, and a different type of complexity than the (relatively) heavy use of metaprogramming in Ruby (relative to JS).