rokstar rokstar - 26 days ago 10
Javascript Question

Is it possible to resolve async function without return keyword

I started to use ES7 feature

async/await
, which gives the best approach to deal with asynchronous tasks, and makes your code cleaner and readable.

However it doesn't give you an access to Promise, created by async function, so if you do some async request in your async function you should promisify it, then await it and then return the result. I mean this:

async function doStuff() {
//stuff...
var value = await new Promise(function(resolve) {
$.get('http://some/url/...', function(result) {
// stuff...
resolve(result);
});
});
return value;
}


What if you could find a pointer to the Promise created by function so your code could look like:

async function doStuff() {
//stuff...
var p = arguments.callee.promise;
$.get('http://some/url/...', function(result) {
// stuff...
p.resolve(result);
});
}


or even:

async function doStuff() {
//stuff...
$.get('http://some/url/...', function(result) {
// stuff...
async.resolve(result);
});
}


This way you don't need to directly access Promises API what makes your code totally focused on task without any besides.

Answer

Is it possible to resolve async function without return keyword

No.

There is no way to get a reference to the promise that the call to the async function created, but there really is no need to access that either (and btw, you cannot .resolve() a promise, you'd actually need to get access to the promise's resolving functions).

The whole point of async/await is to play nice with promises and other thenables. The idea is that every asynchronous function returns a promise, and that you don't have to promisify anything (but if you really have to, do it separately) - and in fact, $.get does return a (jQuery) promise. So simply write

async function doStuff() {
    //stuff...
    var result = await $.get('http://some/url/...');
    // stuff...
    return value;
}

If you really have a callback-taking function, use a simple

async function doStuff() {
    // stuff…
    return new Promise(function(resolve, reject) {
        $.get({
            url: 'http://some/url/...',
            success: resolve,
            error: reject
            // don't do other "stuff" in here
        });
    });
}
Comments