What is the general opinion on HN on the above libraries? Google Closure hardly gets any mention so want to know if there are any developers out there who use Closure and what has been the experience?
Any other suggestions (backbone?) are also welcome
With regard to backbone and the like it really all depends on your ppl resources. If you want corp support you can forget about it. Sencha's ExtJs might be a better fit.
Also note that backbone and almost all the wonderful modules out there haven't even reached 1.0. It is perhaps this that makes Googles offering compelling as they use this internally and relies on a stable API/codebase.
For the record, I am a big backbone, coffeescript fan.
I actually think they fill very different niches. JQuery is for sites that are primarily HTML but require some additional interactivity layered on via progressive enhancement. Closure is meant for JavaScript apps, where the whole client is basically written in JavaScript. Closure provides a lot of services that JQuery doesn't - there's a very full-featured widget library, and a JS compiler to minify your code, and a whole module system with on-demand code loading that's critical when your app becomes large.
The flip side is that coding to Closure conventions is very verbose. It feels like Java, a lot of the time. If your app is going to have hundreds of thousands of lines and dozens of developers, this is the right move. If it's just you trying to bang out an interactive website in a couple weeks, JQuery will let you get the basics done in much less code.
There is a strong belief - at Google and elsewhere - that any engineer should be able to read any other engineer's code. That means getting assumptions down in the code so there's nothing you have to keep in your head.