I do a lot of JavaScript development. A lot of these are mentioned but, here is what I use:
- Notepad++
- Firebug
- IE debugger (F12) and Chrome debugger (F12 on Windows)
- I use Stack OverflowStack Overflow mainly for questions. Coming here has proven helpful as well.
- The first book I used was JavaScript: The Definitive Guide way back when. Currently I don't use books as much as I use sites like MDN or MSDN docs.
- We use some jQuery in places where it makes our life easier as well.
- For unit testing we build our own test harnesses.