[napkindrawing]

As I'm currently building a Serious Application in Backbone (dozens of Models, dozens of Views, a dozen Controllers), the differences between Spine & Backbone to me seem to come down to:

Spine does class/inheritance closer to the "JavaScript" way where properties are resolved correctly at runtime, Backbone seems a little more hackish in this area IIRC (+1 Spine).

Spine seems to have given up the separation between Controller & View. Backbone has a great separation here that has been a great aid to me in refactoring a large application. (+1 Backbone)

Backbone treats collections of Models (Backbone.Collection) as proper first-class citizens. Collections can receive & emit their own events, handle their own serialization/fetching, and make use of all Underscore.js methods (+1 Backbone)

Other than that they seem pretty similar to me. So my verdict: Spine +1, Backbone +2 :)

[jashkenas]

    > Spine does class/inheritance closer to the "JavaScript" way [...]

Nope. See later on in this thread. Backbone uses constructor functions and prototypes, Spine uses Object.create. Both approaches have properties resolved correctly at runtime.

    > Spine seems to have given up the separation between Controller & View.

Nope. Spine Controllers == Backbone Views. Spine doesn't have an equivalent notion to Backbone Controllers (although if one were added, I'd imagine it would be called a Router).

[frekw]

I actually think that Spine seems to implement more sane controllers than Backbone (but I never really liked Backbone's way of doing it in the first place).

Controllers are supposed to coordinate the interactions between views and models by propagating changes and events between the two.

For example, if you had a todosController responsible for controlling a collection of views, there isn't really a clean way (in my opinion) to utilize it from two independent Backbone views without passing the controller through to the view (which makes the view depend on the controller). By handling events in the controller instead of in the view, you remove this dependency (which is also similar to my perception of Cocoa's delegates/SproutCore's bindings, but I may be wrong).

Both Spine's and Backbone's view layer consists of rendering templates to the DOM. To me, a "proper" view layer would include things like positioning and both frameworks seem to utilize CSS to do this, for the most part.

I think of Backbone's controllers as a poor man's State chart, without any enter or exit callbacks (e.g going from "#/" to "#/todos" should trigger a callback that states that I will exit the state "#/", so I can do necessary cleanup).

[manlon]

This is true, but because Backbone made a poor naming choice. Backbone Views are what one normally thinks of as "controllers" (coordinating presentation and models), and the view/presentation layer is not handled by Backbone per se but by something like Underscore templating. Backbone Controllers really are just some helpers to deal with URL hashes.

In my experience Backbone Views become the "top level" of a client-side app, but that is appropriate because they encapsulate controller logic.

[frekw]

Yeah, I'm aware of that, but from my experience the code can end up uglier than it needs to be, either because you need to pass through proxying views further down the chain, or need to duplicate functionality.

I guess I just dislike the convention of interacting directly with collections from places where it shouldn't be done, e.g a todoView removing its own Todo from the collection (hence the risk of duplicating functionality throughout your code), instead of asking a proxying controller to do it. I think this is the reason as to why I've seen a lot of Backbone code where a reference in to the view is stored in the model itself (e.g http://documentcloud.github.com/backbone/docs/todos.html), which disgusts me since it completely misses the point of MVC.

Also, events passing feels more complicated than it would need to be (even if you can always include Backbone.Event).