1) Streams (types, difference, usage)
2) Node architecture (libuv, v8, …)
3) EventLoop (explain how it works)
4) setImmediate, process.nextTick, setTimeout(cb, 0) (difference, usage, …)
5) Middleware (what is that, how to use, chain of responsibility pattern)
6) EventEmitter (observer pattern, usage…)
7) Promise, async/await, generators (usage, differences)
8) Modules (commonjs/ES6, usage, difference)
9) Function context, scope (arrow/plain, difference)
10) Garbage collector (how it works)
11) REST (codes, methods)
12) Testing (unit/system, libraries)
13) Iterators