Sproutcore vs jQuery +backbone.js

someone forked a MooTools version, so it is doable.

Zepto is a lighter-weight jQuery compatible library- so you shouldn't feel as bad about having it as a dependency. It might also be possible to have a stripped build of jQuery.

Backbone.js is easily one of the finest products I have had the pleasure of using. There is a small learning curve but after that, it's butter. The best part, imo, is that more than teaching you to use some foreign dsl, using backbone.js makes you just better as pojs because it teaches modularity, sane callbacks, and a whole mess of other stuff. jashkenas and the other guys behind backbone did a really good job at making a tool that felt like native javascript.

I've done some interesting applications with Backbone.js over the last 2 months or so (for anyone that uses uTorrent, here's one: http://apps.bittorrent.com/ucast/ucast.btapp all in about 800 lines of code, just unzip the btapp file if you'd like to see the source). After trying other things like SproutCore, Cappuccino or Evently, I'll never go back.

I actually ended up being surprised by how backbone changed what I do with javascript. With backbone, you can create views that are really just widgets. For example, if you have a list item, you can create a view specific to that list item. Then, all the events and state for that list item are encapsulated right there. No need to store state in the DOM, you can just fetch it from the model when it happens. This then allows you to bubble events up through the parent views to change the entire page's state. Because of the separation, you really end up having little pieces of javascript that only know about themselves and the whole picture ends up being considerably less fragile and easier to debug.

I'm also a big CouchDB fan. Since backbone models are just documents, the integration with CouchDB is very minimal and you get instant serialization of user state (it really is that easy, to pimp one of my projects: https://github.com/pyronicide/backbone.couchdb.js). There are no server handlers you need to write (hell, don't forget you don't even need to run a web server, Couch'll do that for you!) and you end up with less complexity overall.

Wouldn't you think that http://dojotoolkit.org/ might be a good alternative?

I'm currently using Backbone.js + JQuery in my startup and my decision came down to the following conclusions:

Use Sproutcore or Cappucino if you are trying to emulate a native desktop app and where long load times are acceptable (i.e. the user sacrifices time to load everything to not have to wait much if at all after the initial loading). Also use these two environments when your users are Apple Users.

Use Backbone.js + JQuery in a small startup environment with a lean team where the front-end devs are multitalented (i.e. they can easily move between html/css and javascript)

Use a MVVM framework with bigger teams () and with teams where your front-end guys may be good with html/css and graphic design but have limited or non-existent stills when it comes to programming intermediate to advanced javascript and handling mildly to very complex programming concepts.

MVVM has value and I believe it was invented to solve a common communication/coordination problem in corporate-style environments and especially with "silo"-ed teams and matrix management. However, the way I see it will slow down a good front-end developer. MVC is much more powerful and flexible in the hands of a good dev. MVVM just adds another layer of abstraction so the pure HTML/CSS and graphic design guys don't have to get their hands dirty with real programming.

If you are going the Sproutcore/Cappucino route, you really are commiting yourself to a platform and certain ways of doing things from a user interaction perspective. You will gain a lot in not having to build some basic, common interfaces, but you will lose when you need to invent and create your own custom interfaces.

Summary:

Backbone.js + JQuery = Flexible, powerful, lean - Good for experienced devs

Knockout.js = Less powerful, simple = Overcomes coordination and cooperation issues in teams where "the left hand doesn't know what the right hand is doing"

Cappucino/Sproutcore = Complex apps built fast, inflexibility in interface design patterns. Good for "native-style" apps.

Anyways, those are my opinions. I encourage you to challenge me on anything you don't agree with as my experience with Sproutcore/Cappucino is limited to just research and I only built one small app with Knockout.js.