How does async function behaves when some of its inner async functions are called without await

Question

I'm looking at this article about async/await. It contains the following:

Sometimes, you only want to trigger an asynchronous computation and are not interested in when it is finished. The following code is an example:
async function asyncFunc() {
    const writer = openFile('someFile.txt');
    writer.write('hello'); // don’t wait
    writer.write('world'); // don’t wait
    await writer.close(); // wait for file to close
}

I'm interested in how the function proceeds if there is no await for asynchronous functions calls insdide in this particular case. So can somebody please rewrite the above example using promises so I can better understand what's going on?

EDIT

As I understand, it can be rewritten like this:

async function asyncFunc() {
    const writer = openFile('someFile.txt');
    writer.write('hello'); // don’t wait
    writer.write('world'); // don’t wait

    return writer.close().then(()=>{

    });

}

Thanks

That example doesn't make much sense. How would you close the file before having completed writing? It should wait anyway. — Bergi, May 26 '17 at 07:42
@Bergi, yeah, thanks, maybe that's what confusing me. But still rewriting it with promises is possible, right? Can you maybe come up with a better example? — Max Koretskyi, May 26 '17 at 07:44
You might want to have a look at [this answer](https://stackoverflow.com/a/43547745/1048572) — Bergi, May 26 '17 at 07:45
Thanks, I [added clarification comment](https://stackoverflow.com/questions/43547606/implementing-coroutine-control-flow-in-javascript/43547745#comment75407212_43547745) there. Take a look if you have time. Appreciate — Max Koretskyi, May 26 '17 at 09:04
@Bergi, is the way I rewrote the function correct? I added that to the question details — Max Koretskyi, May 30 '17 at 05:32

score 2 · Answer 1 · answered May 30 '17 at 05:50

async function asyncFunc() {
    const writer = openFile('someFile.txt');
    writer.write('hello'); // don’t wait
    writer.write('world'); // don’t wait

    return writer.close();
}

ES2015:

function asyncFunc() {
    const writer = openFile('someFile.txt');
    writer.write('hello'); // don’t wait
    writer.write('world'); // don’t wait

    return writer.close();
}

assumption, is that writer.close(); always returns a promise, and the resolution value is not used by the caller.

yeah, I thought about simply `return writer.close();`, but I try to translate every `await` into `then` — Max Koretskyi, May 30 '17 at 06:27

How does async function behaves when some of its inner async functions are called without await

EDIT

1 Answers1