To be good at something, you do not need to know things outside of the area. It might however be helpful if you need to go "outside the box". But to be an expert at the things in the box, you only have to know about the box ...
That said, before I started with Node.JS and understood it's "patterns" JavaScript was just some evil necessary to get things to work. But after learning the module patterns of Node.JS, JavaScript started to get fun!! And the more ppl that understands "modules", the more fun it gets! So go learn about modules and even try making your own!
I guess Node.JS is now part of the JavaScript box.
That said, before I started with Node.JS and understood it's "patterns" JavaScript was just some evil necessary to get things to work. But after learning the module patterns of Node.JS, JavaScript started to get fun!! And the more ppl that understands "modules", the more fun it gets! So go learn about modules and even try making your own!
I guess Node.JS is now part of the JavaScript box.