Which brings up a good point: Where are the Javascript IDEs?
Since hard drive space is cheap, I have different Eclipse installations for each language I use. This seems to cut down on plugin hell and slowdowns that people often complain about.
I can't comment on how good Eclipse is actually for web development, but for embedded Javascript scripting it works splendidly. Most precisely, it lets me zoom in and out of abstractions in a large project with multiple files with ease.
(disclaimer: I currently work at MSFT, but am not anywhere near the VS team).