Client-side javascript to support promises, futures, etc.

Question

I'm really interested in implementing Promises and related features in client-side Javascript. From what I've seen, the focus in implementing these technologies in Javascript seems to be on server-side javascript (SSJS) with Promises in CommonJS. Ideally for me, I would find a solution that works well with jQuery or Google Closure Library, but I'm open to any solution.

• Is it possible to use the CommonJS solution client-side? This Sitepen article has some great information on promises in CommonJS, but it is focused on SSJS.
• What other libraries are available that implement promises that can easily work client-side?
• What are your impressions, experience, and feedback on any toolkit you have used?

I've found a few client-side implementations, but I'm unclear on how robust they are. Is there any library that has become the de-facto standard? Is a mainstream library (like jquery) already working on something similar for a future release?

• MSDN library has an implementation of promises and futures
• An implementation is on github and described in this article - this one looks pretty good
• Dojo has a feature called Deferreds, but the Sitepen article points out flaws
• Douglas Crockford talks about Promises, but I can't locate his implementation

Any others? Anyone have experience with any of these and have a preference? Is one better than the others?

Answer 1

I'm the developer of FutureJS.

I started with the snippets from Crockford's slides. In fact, here's the original & unadultered implementation.

Now both parts of that blog post are part of the FuturesJS Documentation and there's more to come.

I'm very willing to modify FuturesJS to fit CommonJS if and when they have an official standard. I'd love to have you join the mailing list and give me your feedback and suggestions.

While I'm plugging, I'd also like to add that the aim of FuturesJS is to become the Async Toolbox of JavaScript. I also have subscriptions, triggers, synchronizations. As I run into more organizational issues and see what others have done I'll continue to update the library with best-practice solutions.

=8^D

P.S. FuturesJS will work alongside jQuery, Dojo, etc without issue. There are no dependencies. Also, I believe that it will work with Node.js and Rhino. If not, let me know and it should be a quick fix.

Answer 2

http://www.sitepen.com/blog/2010/05/03/robust-promises-with-dojo-deferred-1-5/ should answer your question exactly