You should know the stuff you work with. It does not make a lot of sense if you learn about streams, but never actually use them. Important is how core stuff works: the NodeJS and V8 internals. That kind of knowledge can always make life easier for you, even when using abstract frameworks.
require() work? (hint: put a breakpoint on a require statement and step-in)console.log(arguments.callee.toString());)Since NodeJS is opensouce, reading the actual source can give you a deep understanding (at least that's what I did)