Good info all. I do have a question.. what constitutes a web site vs a web app? In my career everything I've worked on has basically been what I always thought was a web app. It's essentially a desktop app done in the browser. In years past it wasn't quite as fancy as today's web apps, but basically you'd have users create accounts, log in, manage things, send forms, etc.
So when you say jquery is more suited to web sites, what exactly does that mean and how does ext-js differ in what it produces? I am thinking with the various UI plugins, you can build a web app with jquery that functions just as well as an ext-js or a hand coded site. What draws me to ext-js, is the rich components it provides without the need to worry about the html/css and layout and cross browser issues. I am hoping once I learn it a bit more, I can more rapidly build nice fully functional desktop-like apps for the web, because while I know some html and css, I am far from knowledgeable enough to deal with all the intracacies that go along with the different browsers and platforms and versions of those browsers.
I think of the difference in terms of what the architecture of your "site" or "app" actually is. For example, there's a LOT of jQuery out there used on websites for the express purpose of enhancing web pages...whether it's animations, form validation, etc. In these cases, however, the JS library is being used to enhance existing HTML pages.
What I think of as web "apps", on the other hand, are those sites (typically single page, like Gmail) which are built particularly using a specific framework in order to deliver a cohesive, unified experience.
As others have mentioned, there's no right answer regarding which to use. I use jQuery at work all the time when I have a simple web form that needs a date picker and simple form validation. To me, this is using jQuery advantageously for what it's really good at--lightweight, simple enhancement.
Excellent response. That makes sense. Because I am not a strong html/css UI developer, more back end stuff, I am hoping ext-js fills that void where I feel like I can't build a fully functional site because I don't know enough of the web UI to really make it shine. Even for a small site I would consider ext-js + back end rest api to interact with the ext-js UI simply because I'd rather take advantage of what ext-js provides for me that I lack. It reminds me a bit of some Swing frameworks that built on swing to provide a Eclipse like application framework with menus, widgets, etc so that you didn't have to do all that yourself. You simply glued the code behind the components/events and database side of things.