Use jQuery or Q.Js for promises
breeze, javascript, jquery, promise, q
Solution
Both are based on the Promises/A standard and implement a `then` method (though only current jQuery, they once had a incompatible `pipe` instead of `then`). However, there are a few differences:
- Q has exception handling. All thrown errors in the async `then` callbacks will be caught and reject the promise (and will only get re-thrown if you call `.end()`). Not sure whether I personally like that. It's the standardized way which jQuery does not follow, rejecting from `then` in jQuery deferreds is much more complicated.
- Q promises are resolved with a single value/reason (like you return/throw it from `then`), while jQuery allows multiple arguments in `resolve`/`reject` calls on its Deferreds.
- Q has lots of Proxy methods which will allow you to modifiy future values
- Q has `.all` and similiar, which are more complicated with jQuery (`$.when.apply($, […])`).
- Q does explicitly work with ticks in the event loop and guarantees asynchronity, while jQuery can be synchronous as well. This is now required by the Promises A/+ specification.
… which is basically Promises/B. As you can see, the `Q` API is more powerful, and (imho) better designed. Depending on what you want to do, `Q` could be the better choice, but maybe jQuery (especially if already included) is enough.
Problem
I'm looking into BreezeJs and there samples are using Q.js for promises to handle asynchronous calls. John Papa is also using Q. JQuery has promises as well. What are the differences between the two?