Alternative way to create a promise with q

Question

I know how to create a promise in Kris Kowal's q with var defer = Q.defer();, calling defer.resolve(); and/or defer.reject() and return defer.promise. But reading the docs, it seem's there is an alternative way to create a promise...

From the docs:

Q.Promise(resolver)

Synchronously calls resolver(resolve, reject, notify) and returns a promise whose state is controlled by the functions passed to resolver. This is an alternative promise-creation API that has the same power as the deferred concept, but without introducing another conceptual entity.

If resolver throws an exception, the returned promise will be rejected with that thrown exception as the rejection reason.

This is, what I've tried:

function () {
    return Q.Promise(function (resolve, reject) {
       (...do something...)
       resolve(5); // or: reject(error);
    });
}

But this doesn't work as expected! Can someone give an example, how to use Q.Promise?

UPDATE: Thanks for downvoting! I asked for an usage example, therefore a simple "you use it in a correct way" is more helpful! Btw: it fails silently and yes, I attached an error handler!

The reason, why the function is unnamed, is that I use it together with map and reduce to create a delayed chain of promises, but it seems, the resolver functions are never called... Therefore I asked for a (again) usage example...

**How** doesn't it work? What error do you get? What version of Q are you using? — SLaks, Oct 23 '14 at 15:28
"this doesn't work as expected". Are we meant to guess what's going wrong for you? — spender, Oct 23 '14 at 15:33
You did not name your function, your JS syntax is incorrect. — Benjamin Gruenbaum, Oct 23 '14 at 15:38

score 0 · Answer 1 · answered Oct 23 '14 at 15:49

0

Looking at your 2 examples, I'm guessing you are doing this:

var q = require('q');

Therefore Q.Promise won't work, but rather q.Promise will.

answered Oct 23 '14 at 15:49

Catfish

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The doc suggests ```var Q = require('q')``` and ```Q.Promise()```. In my code I use a lowercase **q** and ```q.Promise()```. But such errors are not really reasons to ask on SO... – Christian Rädel Oct 23 '14 at 16:43

Alternative way to create a promise with q

1 Answers1