mark242 on Async/await support in Firefox

Comment on Async/await support in Firefox

Dear Javascript coders:

If you wind up writing the word "await" in your codebase more than once, you're doing it wrong. You will quickly see how futures/promises wind up taking over all of your code. This is a very good thing. You shouldn't need to block, ever.

Sincerely,

Scala coders

mehwoot 9y

Am I missing something? Await doesn't block. It's just syntactic sugar for Promise.then(() => {}) without having to go down into callback hell.

It makes code more readable and easier to write, but doesn't fundamentally change how it is working under the hood, as far as I am aware.

mark242 9y

  var txt = await read();
  // This code is blocked until read() completes.
  console.log(txt);

kinkdr 9y

It is in essence:

    read((err, txt) => {
        console.log(txt)
    })

     read().then((txt) => console.log(txt))

Why is it bad?

danneu 9y

Await doesn't synchronously block in Javascript.

http://docs.scala-lang.org/overviews/core/futures.html#block...

olalonde 9y

And how do you suggest to do that without "blocking"? :) Sure, you could use a stream but that isn't always possible or practical.

solipsism 9y

That's not what blocking means.

c-smile 9y

Well, it depends...

async function is blocked on await statement, after all that's why it has such a name.

It does not block the whole VM but task (async function) is effectively blocked for an observer inside it.

solipsism 9y

Yes but when you talking about async/await, "blocking" means "blocking the thread". And this is very clearly what mehwoot meant.

kinkdr 9y

Care to elaborate a bit? Just trying to understand why async/await is bad. In my mind it makes for much cleaner code that the callback hell.

Also, how is Scala doing it?

pkolaczk 9y

Scala is doing it exactly as in JS. We have async/await as a macro library transforming the code to a FSM. The original author posting this probably didn't know that, under-the-hood, await doesn't really block in Scala nor in JS.

taeric 9y

Dear Scala coders,

Why have you decided to rewrite everything?

Sincerely, Everyone else. (Obviously not JavaScript coders, sadly...)

P.s. I can only hope you have a somewhat sane release story now.

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