It's too bad that Node.JS is mostly used as a scaffolding and glue language for web frameworks, while where it really shines is as a replacement for a systems language. You sacrifice 4x performance to get better safety, less development time, easier code, easier deployment, and a more open and friendly ecosystem.
Replacement for a systems language? How are dynamically-typed callbacks, as in Node's fs library, in any way comparable with, say, go routines or good old procedural C++? Async is the worst programming model for building systems.
The Node.JS libraries also have Sync (not async) alternatives. But everything is async by default. JS/Node is single threaded, but supports multi process concurrency with message passing and sharing of sockets.
I personally prefer callback convention, but it's not the only paradigm. Primises/Futures, and async/await is also very popular.
Node.JS makes you think async, which has a learning curve, but I prefer that over multi threading locks and data races.
Go is also great. But I think JavaScript is much easier.
