I have a couple dozen Asp.Net applications that I use as data-driven components when I build client websites. It's very tedious and time-consuming to integrate these apps manually when creating pages so I want to develop a front-end page builder tool, something like a very scaled down DotNetNuke.

I want to use a layout manager for defining panels on the page into which I can drag/drop ajax-powered containers that will be populated with my data-driven components. The containers will need to be both dragable and resizeable and I'll need completely control over where to drop them in the panels (side-by-side, top-down, etc).

I've been looking into the javascript libraries that are available and a number of them look like they will do what I'm looking for. So far I've been looking at DOJO, Yahoo's YUI,
Prototype, and Ext JS.

I'd like to get your recommendations and experiences with these, and any other js libraries. If you've successfully developed any type of UI builder or portal type page using these tools, I'd be very interested in seeing your apps in action.

Thanks.

What about jQuery (http://www.jquery.com)? I've found it's quite easy to use and pretty intuitive.

Another vote (+1) for jQuery :)

twitter.com runs on jQuery...

Mojo is supposed to be good too, haven't used it myself.

My vote is for JQuery. ExtJS has a nice set of widgets but their licensing is all out of whack so any non open source software really should not be using it.

For Some widget like components you can use JQuery UI, but it doesn't have grids and things like that. However there are JQuery plugins that do most of what some of the widget heavy libraries do.

Prototype with script.aculo.us is great!

Another vote (+1) for jQuery :)

And another here.

jQuery really is as it's site says: the write less do more JavaScript library.

Using CSS selectors to group and manipulate the DOM is IMO genious. The extensive OOP nature become second nature after a couple of weeks working with jQuery.