Chaining promises in version 7+

[danamajid]

I'm trying to just do a simple chaining of promises, by first pushing promises to an array and then do Promise.all(array).then(function(results) { console.log(results); }). This used to work just fine in v6.x, but since upgrading to the latest version, it fails.

At the essence, what seems to differ from before is:

console.log(new Promise(function (resolve, reject) {
  resolve();
}));

Previously this would log: { then: [Function] }

Now on version 7.0.1, this results in: { _32: 0, _8: null, _89: [] }

Did I miss a change in API or am I messing things up? :)

[samuelbeek]

+1

[kayvink]

+1

[ForbesLindesay]

then is now on the prototype. What this means is that you can no longer do:

var promise = new Promise(function (resolve) {
  resolve();
});
var then = promise.then;
then(function () {}); // this won't work
promise.then(function () {}); // but this would work fine

If you can produce an example of code that fails, I'd be very happy to look into why it fails.

[danamajid]

Thanks, that did the trick.

For future readers: in order to do Promise.all(promisesArray), the promisesArray should look like: [promiseA.then(), promiseB.then()] and not [promiseA, promiseB] like before.

[ForbesLindesay]

no, there should be no need to do that.

[ForbesLindesay]

If you could provide an example that demonstrates the failure, it would be incredibly helpful.

[ForbesLindesay]

Could you tell me what exactly the failure is when you do Promise.all(array).then(function(results) { console.log(results); })? Do you get an exception? Does it just never resolve?

[danamajid]

No exception and it just never resolves. Just wrote a reduced version but that works like you said – so something else must be causing it.. So I am separating things now to find out. Stay tuned.

[ForbesLindesay]

Are you interacting with any other promise libraries? Especially libraries like lazy-promise (which inherit from promise as a base class)?

[danamajid]

No. Only thing out of the ordinary is that its populating the array inside multiparty's form.on('part').

Can't reproduce a test case right now and have to run. Either way, think it's unrelated to this lib. Feel free to close the issue. Thanks for your help!

[ForbesLindesay]

OK, please post here when you manage to produce a test case. @samuelbeek & @kayvink perhaps one of you can produce an example?

If all the promises were Promises/A+ compliant, then there is a bug in this library so I'd very much like to get to the bottom of it.

[samuelbeek]

@ForbesLindesay unfortunately not, because @danamajid fixed the problem for me too (since we work together).

[ForbesLindesay]

It turns out this is (see #99) caused by asap sometimes calling back twice and sometimes not at all. The offending issue is kriskowal/asap#55, which has now been resolved. Updating asap should be sufficient, which should happen automatically if you delete any caches and re-install.

I will release an update of promise that requires the latest version of asap though to encourage people to update faster.

[edef1c]

Closing this, given that [email protected] resolves this.