Downloaded IntelliJ IDEA Community Edition, realized that it has no JavaScript Support and Debugger.
Any suggestions for good free plugin?
It's not a plugin, but you could try the WebStorm IDE from the same guys.
There's a free trial version (30 days, I think), but it's only €29 at the moment for a personal license (as of May 2011, I don't know the dollar price the website detects where you are and only gives prices for your country of residence).