Is it OK to use async/await almost everywhere?

Question

I\'m currently writing small NodeJS CLI tool for personal usage and I\'ve decided to try ES7 async/await feature with Babel.

It\'s a network tool so I obviously hav

Answer 1

I had the same question.

And found a great answer here → ‘Pitfall 3: your whole stack needs to be async’

No, async/await is not contagious. (I believed the same thing for some time, too)

You can always treat the result of a sync function like a promise, and you are back to normal.

From developer.mozilla.org:

The async function declaration defines an asynchronous function…

Return value: A Promise which will be resolved with the value returned by the async function, or rejected with an uncaught exception thrown from within the async function.

Sample code:

const log = console.log; // just lazy shorthand

// just to delay, as seen in many places
function promiseTimeout(time, value) {
    return new Promise(function(resolve, reject) {
        setTimeout(function() { resolve(value); }, time);
    });
};

// the thing you care about
async function foo() {
    Promise.resolve('here')
    .then((a) => {log('doing stuff '+a); return 'pear'})
    .then(function(v) {
        return promiseTimeout(1000,v)
    });
};

// treat async-function like promise:
foo().then(function(){ log('folling up in main, ')});
// log('bad end');

gets you:

doing stuff here
following up in main

Enabling 'bad end' would show up too early. You can only await stuff it you use await. (And if you do, remember: It's just syntactic sugar, saving you of stuffing your follow-up code into .then() clasuses... nice, but no more than that.)