What Environment do you use for Javascript dev?

Hi all, I'm a C coder, occasionally I use Java so for most of my development I use VIM or eclipse. Now I'm trying to build some web application: javascript applications (looking also into phonegap). I'm having a hard time finding a good dev environment. So far I'm using firefox + firebug and Xcode for editing. I'm new to web dev, so I'm afraid I'm missing something. Is there a very powerful IDE ? So I don't have to open my things in firefox and hope they work ? Thanks !