await setTimeout in async functions

[Andrea Giammarchi]

Why not using fill setTimeout API, also granting you args are those passed
at the invocation time and no possible mutation capable of affecting `
computeResult` could happen later on?


```js

const asyncFunc = (...args) => new Promise((resolve) => {

  setTimeout(resolve, 1000, computeResult(...args));

});

```


Otherwise you can always do the following

```js

const asyncFunc = (...args) =>

  new Promise(r => setTimeout(r, 1000))

  .then(() => computeResult(...args));

```


isn't it?



On Tue, Feb 28, 2017 at 4:40 PM, Jérémy Judéaux <jeremy.judeaux at volune.net>
wrote:

> Let's take a simple asynchronous function
>
> ```js
>
> const asyncFunc = (...args) => new Promise((resolve) => {
>
>   setTimeout(() => resolve(computeResult(...args)), 1000);
>
> });
>
> ```
>
>
>
> One problem in this example is that any error thrown by `computeResult`
> will not be correctly handled. This can be solved with an `async` function:
>
> ```js
>
> const delay = (duration) =>
>
>   new Promise(resolve => setTimeout(resolve, duration));
>
>
>
> const asyncFunc = async (...args) => {
>
>   await delay(1000);
>
>   return computeResult(...args);
>
> };
>
> ```
>
> It's always better to handle errors. So I would not be surprised if a
> similar pattern become favoured over the use of `setTimeout`, when writing
> and learning asynchronous functions.
>
>
>
> Writing a `delay` function is easy. But a standardised statement
> (`await*delay`, `await.nextTick` or whatever name or syntax) would
> highlight these patterns. It would also be an opportunity to standardise
> `setTimeout`, `setImmediate` and such, without risking incompatibilities
> (I've seen that point reported in a recent email).
>
> Cancellation would probably be a sensible point, but it may also be left
> to a more global solution about cancelling `async` functions.
>
>
>
> I’ve found some old discussions about a Promise-returning delay function,
> showing that the (lack of?) concept of event-loop in ES would be a problem.
>
>    - https://esdiscuss.org/topic/promise-returning-delay-function
>    - https://esdiscuss.org/topic/a-promise-that-resolves-after-a-delay
>
> Also IMO it would be easy to forget the `await` keyword.
>
>
>
> Is it worth discussing again, in the context of `async` functions?
>
>
>
>
>
> Regards.
>
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>
>
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