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JavaScript async/await implemented in V8

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Re: JavaScript async/await implemented in V8

#51

Post by jeswin »

avodonosov wrote: post #30

what's the point of explicitly declaring functions "async", and then explicitly saying "await". IMHO all this could be done automatically by language.

Because you don't always have to await a function, and it isn't always possible for the runtime or language to decide whether to "await" or not.

  /*
    The following code may or may not use an await.
    Not await-ing would be better user experience.
  */

  async function sendEmails(id) { ... }
  
  async function signUp(userData) {
    const user = await db.saveUser(userData);
    sendEmails(user.id); //

Re: JavaScript async/await implemented in V8

#52

Post by Bahamut »

coldtea wrote: post #41
Bahamut wrote: post #36

Earlier quoted context omitted.

To correct this a little, the proper way to catch with promises is .catch, not with a try-catch inside a .then - that is an antipattern. The promise examples as written are not proper promise usage. I'm also in the boat of confused people of why is async-await requested by a good portion of the js community - wrapping the block within the function in a try-catch seems like a bad idea, a brute force mechanism. IMO thi…

> To correct this a little, the proper way to catch with promises is .catch, not with a try-catch inside a .then - that is an antipattern. Depends whether you can survive and continue from an exception inside the .then to the next step or not.

Promises catch exceptions and automatically reject: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe... . I've never seen a promise not do this - do you have an example where this is not the case?

Re: JavaScript async/await implemented in V8

#53

Post by dfischer »

tanto wrote: post #4

The moment I started using async await (with babel) combined with the new fetch API so many libraries got obsolete. Getting data is as easy as: async function main () { try { const res = await fetch('https://api.github.com/orgs/facebook'); const json = await res.json(); console.log(json); } catch (e) { // handle error } } So I am quite happy when this lands in modern browsers asap.

What do you use for the new fetch api on node?

Re: JavaScript async/await implemented in V8

#57

Post by sotojuan »

viperscape wrote: post #19
tanto wrote: post #4

The moment I started using async await (with babel) combined with the new fetch API so many libraries got obsolete. Getting data is as easy as: async function main () { try { const res = await fetch('https://api.github.com/orgs/facebook'); const json = await res.json(); console.log(json); } catch (e) { // handle error } } So I am quite happy when this lands in modern browsers asap.

The try and catch inside the async function is also great. Curious though, is using const over let common? I usually use const for imports and module level globals, and let inside functions. I recently got back into javascript, and it's nice to see it flourishing.

I'm alone in this but I prefer `let` over everything else unless it's something like Redux action strings, database connections strings, or anything of the like. I rarely use `const` for the ridiculous reason that I find it too long (5 characters!). `let` is short and reads nicely and my programming style in general never mutates stuff anyway (I use Ramda/always return new data).

That said, `const` is picking up to be the default for everything. I can definitely see good reasons to use it when declaring functions and required modules or working in a team.

Re: JavaScript async/await implemented in V8

#59

Post by mikeryan »

dfischer wrote: post #53
tanto wrote: post #4

The moment I started using async await (with babel) combined with the new fetch API so many libraries got obsolete. Getting data is as easy as: async function main () { try { const res = await fetch('https://api.github.com/orgs/facebook'); const json = await res.json(); console.log(json); } catch (e) { // handle error } } So I am quite happy when this lands in modern browsers asap.

What do you use for the new fetch api on node?

I don't use it on Node but this syntax is great on react native.

Re: JavaScript async/await implemented in V8

#60

Post by lewisl9029 »

g_delgado14 wrote: post #24
viperscape wrote: post #19

Earlier quoted context omitted.

The try and catch inside the async function is also great. Curious though, is using const over let common? I usually use const for imports and module level globals, and let inside functions. I recently got back into javascript, and it's nice to see it flourishing.

const is more declarative as you can immediately tell that the data isn't going to change throughout the duration of the program (although technically you can change the data, just not the reference).

> although technically you can change the data, just not the reference

This is why I'm hoping to see native JS immutable data structures eventually (maybe it's already in a proposal somewhere?). ImmutableJS and Mori are great, but having a native solution that's available everywhere would be ideal.

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