I can't imagine choosing to write Javascript on the server, but considering its popularity I'm wondering if I'm wrong. So I'm curious as to the reasons people chose Node.js and whether you would recommend it, anybody willing to share their experiences?

I've got over a decade of professional experience in C#, Python, and Java. I'd consider myself a Java developer before all else, yet I still turn to Node.js for proof of concept projects because certain things are just quicker to implement.

Here's the major caveat, out of, say 100+ PoC/prototype projects I've ever done, I've taken two to 'production'. I put production in quotes because they were actually internal services as part of our build and delivery pipeline. It's a major pain in the butt to monitor and keep Node.js running production-like in even remotely similar ways you would with Java, .NET, Python, or even PHP for that matter. I don't expect such drastically different technologies to be exactly alike for production workloads, but there's usually analogous ways to do X, Y, or Z.

You know where Node has been awesome? You land a project with a real tight deadline and its more of a fire and forget project (think interactive 'experience' at a major gaming conference for instance). It needs to run pretty well for a short period of time with a narrow scope of functionality, but some of that functionality is non-trivial. I absolutely love Node for that.

thesmallestcat

Can you elaborate on the "major pain in the butt to monitor and keep Node.js running production-like" What sorts of issues did you face? Certainly .NET and Java have more tooling, but I haven't noticed a difference between keeping a Node process up as opposed to a Python one. Hard to compare to stateless PHP.

stickfigure

The default behavior for Node when there is an uncaught error is to crash the process, killing all requests in flight. Even if you go out of your way to stop this default behavior, errors still likely leave the process in an inconsistent state. Node can't just unwind a few stack frames like synchronous platforms.

Do you read JSON from ajax post bodies? Do you access fields in that JSON without sanity checking it? Try passing JSON that's missing one of those critical fields (as, say, a griefer might do). What happened to your app?

manyxcxi

You nailed it. Three major things I care about for my application:

- Logging

- Metrics/Instrumentation/Tracing (memory usage, transactional performance monitoring, etc)

- Surviving exceptions

All of these are either very immature in Node or simply so far behind they may as well not exist. By nature of running in an application server, you do get a lot of benefits right off the bat for all of those, but even if you're running an executable jar instead of deploying to Tomcat stray exceptions will in almost no cases cause your application to simply die for all requests.

Also, say what you want about the verbose try/catch Exception model, but at least you can count on it. Am I getting an Error in this callback or is an exception going to get thrown? Oh, they leaked an exception when I was prepared to handle an Error and now my entire server is down. Does your process automatically restart? Not likely unless you spent a lot of time hand crafting your service to be daemonized, which is generally FAR beyond the scope of most developers I've met in any language (which also upsets me).

NoInkling

Promises and now async/await go a long way to remedy the discrepancy between synchronous exceptions and asynchronous errors, by helping ensure that they both end up as promise rejections (as long as promises/async functions are your de facto async abstraction) while also being handleable with try/catch. The Koa framework (and in the future Express I believe) is designed around this concept, so middleware-level promise rejections can be handled in a single place, and by default simply produce an HTTP error response. It is a shame that it's going to take a while for the Node stdlib to catch up, however.

Also I thought something like PM2 (https://github.com/Unitech/pm2) or Forever (https://github.com/foreverjs/forever) was pretty much standard for production Node apps?