> "relative absence of blocking IO calls."

Do not confuse "language" with "standard library".

The whole event loop idea, which is core to javascript, allows for the single-threaded non-blocking I/O in a way that no other popular language does. Because of this, javascript has features that make this type of programming easy - first-class functions, anonymous functions, etc.

So, yes. Non-blocking I/O is a standard library feature, but it works because of language features.

> "The whole event loop idea, which is core to javascript, allows for the single-threaded non-blocking I/O (...)"

Event loops are not a property of JavaScript of any other programming language: Every single GUI Win32 application ever written in C directly calling the WinAPI contains an explicit event loop.

> "(...) in a way that no other popular language does. Because of this, javascript has features that make this type of programming easy - first-class functions, anonymous functions, etc."

JavaScript is hardly the only language, or even the only popular language, to ever have first-class procedures or anonymous procedures. You know what (at some point in time) widely taught language has a procedure data type[1]? Pascal. So why not Node.pas instead?

> "So, yes. Non-blocking I/O is a standard library feature, but it works because of language features."

That countless other languages have. Most of them a lot better designer than JavaScript.

===

[1] Edit: I originally suggested Pascal has anonymous procedures, which it does not.

> allows for the single-threaded non-blocking I/O in a way that no other popular language does.

C# Async and Await - http://msdn.microsoft.com/en-us/library/vstudio/hh191443.asp...

Twisted (Python) and EventMachine (Ruby) don't all of these do the same thing?

Yes. But they are tacked on to the language after the fact rather than built in from the beginning. My experience is that both language and libraries support that kind of pattern better in node than in Python (no Ruby experience with async).

I believe twisted was an inspiration for node.

were those in the language before or after node came out?

async/await are just sugar over the much older asynchronous delegate pattern that has been in the language since day one. So yes, they were.

are they widely used in APIs to e.g. send a query to the sql database or open a file?

Yes.

In .Net 4.5 there are Async versions of the web, file, stream, image and SQL category of functions.

It's also making its way into ASP.Net layer.

Well, the browser implementation I guess. The point being the correct mindset.

"Mindset" is not a property of programming languages. "Semantics" is. And JavaScript's semantics is, by any reasonable assessment, a huge pile of crap.

Meh, whatever. I can’t believe people still have flamewars about programming languages on the Internet like it was still 1996.

I was not trying to ignite a flamewar. I was just correcting the mistaken idea that JavaScript's "relative absence of blocking IO calls" is somehow a property of the language itself.

In any case, the real issue at stake is whether there is anything about Node.js that makes it particularly good for writing server-side applications. As far as I can tell, the only thing Node.js brings to the table is an event loop. Event loops are not a particularly earth-shattering concept: Anyone who has written a graphical Win32 application by directly using the WinAPI has written an event loop (message loop in Win32 parlance). I do appreciate not having to write the loop myself, but:

1. An event loop can only handle concurrent I/O. Furthermore, because the event loop is hardcoded into every single Node.js instance, there are two legitimate choices that are nevertheless unavailable to a Node.js programmer: a) disabling the loop, if he does not need it, b) spawning multiple event loops as separate threads within a single Node.js instance.

2. Node.js offers no support whatsoever for concurrent computation. I know, I know, all your Web application does is move data between a database and a client. But, if the only use case of Node.js is going to be making Web applications, would it not have been better to make a Web application framework, and provide it as a library?

Languages that actually provide concurrency support (Erlang, Haskell and Rust, to name a few) make writing event loops as easy as it used to be in the 1990s. On top of that, they can be used to write server-side applications that scale.

Node was created to make scripting fast servers easy. Nothing more, nothing less. Because JS (as implemented in the browser and known by many programmers) didn't carry the baggage of blocking IO calls, Ryan thought it would be a good language for an event-loop based server.

History of Node.js: http://www.youtube.com/watch?v=SAc0vQCC6UQ

Fast Web servers. There is absolutely nothing there that I could use to make, say, a fast database server.

yes, fast web servers.