techno.blog("Dion")

Roberto Saccon has given the Bespin project a nice gift, by porting the Bespin codebase to Dojo. This was a lot of work and is very much appreciated. The obvious question is going to be “Why did you decide to change from Prototype to Dojo?”

Firstly, Ben and I really like Prototype. I am a Ruby guy, so it feels good to me. I talked about it a bit here, and I will use Prototype in many projects in the future.

The state of Ajax frameworks is quite interesting. On the one hand, many of the top dogs have actively learned from each other which has lead to many of them offering similar functionality. For example, Dojo and Prototype can do a good job with DOM selectors, which jQuery is known for.

Although you can do a good job in any of the top libraries, they still differ in scope, and are optimized for certain use cases, project sizes, and functionality wants.

jQuery offers a phenomenal API for doing stuff with the DOM. It feels right. It is also trivial to extend this world, which has lead to the huge number of plugins to do just that. Because of the clean, simple API, we have seen a huge surge in jQuery usage and interest. I would say that it is optimal for designers and beginner JavaScript folk. This is not to say that it isn’t also great for experts. There is large support from folks like Simon Willison. John Resig did something amazing. If you think functional, this will be your cup of tea even above and beyond.

Prototype goes a little further in that it offers more sugar on top of the language itself. Some find the strapping on of methods on core Objects as obscene. Personally, I love it. It just feels so much nicer for me to say array.last() or array.include(thing), compared to dojo.indexOf(array, item) > -1 for example. In fact, looking at a bunch of code has me feeling a touch nuts with all of the “dojo.” items in it. My brain is starting to ignore them.

That being said, Dojo’s purity gives you a lot. It may be more verbose to dojo.byId than $, but we have no namespace pollution.

The community quickly wanted us to package up Bespin in a way that we could share things. We wanted the same, and have natural components (e.g. the Editor, Thunderhead itself), and some didn’t like the leakage of the Editor component requiring Prototype which in turn meant pollution into the global namespaces. With Dojo we can hide away nicely, and can even run a build to become foo instead of dojo if we wanted.

Since the community really wanted it, and someone stepped up and actually did it, we accepted the change. On our codebase it had some interesting side effects. For example, before hand we had Prototype, Script.aculo.us, and a slew of third party libraries to give us a bit of this, that, and the other. With Dojo, they had everything we were needing and more, so we could hg rm external/ and be done. We are also doing Comet work and the like, and it fits in nicely.

The first change here was to get Bespin working in Dojo, but now we have more work to make sure that:

• The codebase feels Dojo-y
• Use more of the Dojo features (e.g. dojo.keys for key handling, CSS store, Comet, …)
• Clean up and package our stuff nicely (e.g. bespin vs. editor vs. th)

If you are a Dojo fan, or fancy getting into it anyway, please join in! There are a few Prototype things left around, so some of the spirit is there.

A bit of an aside…

A big pain with Ajax and components, is the whole “I really like that jQuery UI component, but I am using Prototype already…. grrr”. Simon Kaegi of IBM has been putting together some thoughts and code around a JavaScript module system that would enable you to say “I want service X which happens to depend on jQuery, and service Y which depends on Prototype.” I am very interested to see where this goes. We sorely need it! The annoying problem on the client is that having multiple libraries is not cheap. On the server though? Not as big a deal potentially.