Firebug and a good syntax highlighting text editor is about the best combo. It's not necessary to add in much else. With just this combo you get:
- Ability to set breakpoints
- Inspect objects
- Traverse the DOM
- Alter CSS rules on the fly
- See network traffic/responses
- Evaluate and substitute code on the fly in production
And there are tools which add on to Firebug:
- YSlow - Determine "why" your page is slow
- Fireunit - Run unit tests
One of the advantage of Javascript development is that it's flexible and you can get instantaneous feedback while developing. I see no reason to get in the way of that by adding an IDE which includes a "deployment" step.
