Previously it has been possible to temporarily store state information in custom properties against an element via javascript, however embedding state information in a page when generated server-side (and getting a page to validate) always required workarounds. I’ve often resorted to using hidden input elements to expose state information to client-side script, but this should not (and won’t any longer) be necessary.

Javascript is definately back in fashion, with a number of libraries popping up to help out with application development. I think overall this is fine, so long as you have an appreciation of what is actually happening under the scenes. I don’t think a library should dictate the way that you build an application, rather enable you to build it more efficiently.

I’ve started using elements of the Yahoo YUI library which is very impressive. There seem to be a lot of very useful little utility functions available, the kind of thing that you would typically rewrite on each project.

I’m quite curious about how the Microsoft and Yahoo libraries compare. I’ll post some information about this when I’ve had a chance to look in more detail at Atlas.