My team's current project involves re-writing retrieval libraries in JavaScript. We are basically looking for a setup which enables us to apply test-driven development methods. So far we plan to use Vim to write the code, no fancy IDE. For generating output we would use Spidermonkey's shell environment. JSLint could serve as a moderate syntax checking tool. The essential question remains: How do you develop JavaScript (browser-independent) programs? If we are already on the right track, then maybe you can supply us with a few tips and tricks.
It seems like you have a development environment planned already. So what exactly are you looking for? A way to check that your code will run in IE, Firefox, Safari, Opera, Konqueror and Chrome?