How to reduce use of await keyword in async await while maintaining execution order

Question

async function foo() {
  await this.getAsync();
  await this.getAsyncTwo();
  await this.getAsyncThree();
  await this.getAsyncFour();
}

See how foo has multiple await calls, is there a way of simplyfing this while keeping execution order?

I wish it was possible to write something like

async function foo() {
  await 
   this.getAsync(), 
   this.getAsyncTwo(), 
   this.getAsyncThree(), 
   this.getAsyncFour();
}

or

async function foo() {
  await 
   this.getAsync() 
   .this.getAsyncTwo() 
   .this.getAsyncThree()
   .this.getAsyncFour();
}

I fear it's already in it's simplest form. Depending on what you plan to do with the results of those awaits, using the array method below might save you a line or two for the cost of more characters per line of code. — Shilly, Apr 13 '17 at 11:39
Can you post your actual code, please, so that we may judge based on the purpose of those calls? — Bergi, Apr 13 '17 at 12:11
The actual code contains 4 calls in one function scope (backbone js model). Async await have already made life alot easier compared to the nested .then() => {} calls.. — Cisum Inas, Apr 13 '17 at 13:49
None of your functions return anything? Less isn't always more. — jib, Apr 15 '17 at 04:49
@jib in reality they change attribute data on an backbone model, so yeah stuff happen that I need to await for.. — Cisum Inas, Apr 18 '17 at 14:11
I mean once you return something e.g. `let result = await this.getAsync();` then your semantic optimization breaks down. — jib, Apr 18 '17 at 14:59
@jib sure It would break down in some cases, however in my case I am working on attributes directly on the object (an backbone model). This means in the case at hand it would not break down.. — Cisum Inas, Apr 19 '17 at 10:11

Lyubomir · Answer 1 · 2017-04-13T14:43:43.283

3

This will guarantee the sequential execution order you wished for.

async function foo() {
  const functions = [this.getAsync, this.getAsyncTwo, ...];

  for (let func of functions) { 
    await func();
  }
}

edited Apr 13 '17 at 14:43

answered Apr 13 '17 at 11:35

Lyubomir

1

The OP asked for something simpler, not something more complex. – a better oliver Apr 14 '17 at 07:02
You need to bind this, or this will be wrong in each function. – jib Apr 19 '17 at 22:16
depends who calls foo() and he hasn't done it, so I assume it's the same Object :-) – Lyubomir Apr 19 '17 at 22:37

Dom Vinyard · Answer 2 · 2017-04-19T09:21:34.277

1

You can await on a Promise.all()

await Promise.all([this.getAsync(), this.getAsyncTwo(), /* etc */])

edited Apr 19 '17 at 09:21

answered Apr 13 '17 at 11:30

Dom Vinyard

But is get this.getAsync() executed before this.getAsyncTwo()? – Cisum Inas Apr 13 '17 at 11:31
Not necessarily – Lyubomir Apr 13 '17 at 11:31
That is exactly what I want to achieve :( – Cisum Inas Apr 13 '17 at 11:32
I have upvoted you, seems we had similar approach as your edit being more elegant. – Lyubomir Apr 13 '17 at 11:38
3

The second one does not work at all. Neither is the `async` callback necessary, nor does the `this` value in the method work, nor will it be evaluated sequentially, not will anything be awaited at all. – Bergi Apr 13 '17 at 12:09
You're quite right, I had some serious misunderstandings about the way sync worked. Apologies and corrected. – Dom Vinyard Apr 19 '17 at 09:21
So using Promise.all is execution order maintained? :/ – Cisum Inas Apr 24 '17 at 09:39
no, it is not. for maintenance of order, see @leo 's answer. – Dom Vinyard Apr 24 '17 at 15:03

2 Answers2