What are common development issues, pitfalls and suggestions?

Question

I've been developing in Node.js for only 2 weeks and started re-creating a web site previously written in PHP. So far so good, and looks like I can do same thing in Node (with Express) that was done in PHP in same or less time.

I have ran into things you just have to get used to such as using modules, modules not sharing common environment, and getting into a habit of using callbacks for file system and database operations etc.

But is there anything that developer might discover a lot later that is pretty important to development in node? Issues that everyone else developing in Node has but they don't surface until later? Pitfalls? Anything that pros know and noobs don't?

I would appreciate any suggestions and advice.

Answer 1

Here are the things you might not realize until later:

• Node will pause execution to run the garbage collector eventually/periodically. Your server will pause for a hiccup when this happens. For most people, this issue is not a significant problem, but it can be a barrier for building near-time systems. See Does Node.js scalability suffer because of garbage collection when under high load?
• Node is single process and thus by default will only use 1 CPU. There is built-in clustering support to run multiple processes (typically 1 per CPU), and for the most part the Node community believes this to be a solid approach. You might be surprised by this reality, though.
• Stack traces are often lost due to the event queue, so your logging and debugging methodology needs to change significantly

Here are some minor stumbling blocks you may run into for a while (I still bump up against these)

• Remembering to do callback(null, value) on a successful callback. Passing null as a first parameter is weird and thus I forget to do it. Instead I accidentally do callback(value), which is interpreted as an error by the caller until I debug into it for a while and slap my forehead.
• forgetting to use return when you invoke the callback in a guard clause and don't want a function to continue to execute past that point. Sometimes this results in the callback getting invoked twice, which causes all manner of misbehavior.

Here are some NICE things you might not realize initially

• It is much easier in node.js, using one of the awesome flow control libraries, to do complex operations like loading 3 network resources in parallel, then making 2 DB calls in serial, then writing to 2 log files in parallel, then sending an HTTP response. This stuff is trivial and beautiful in node and damn near impossible in many synchronous environments.
• ALL of node's modules are new and modern, and for the most part, you can find a beautifully-designed module with a great API to do what you need. Python has great libraries by now, too, but compare Node's cheerio or jsdom module to python's BeautifulSoup and see what I mean. Compare python's requests module to node's superagent.
• There's a community benefit that comes from working with a modern platform where people are focused on modern web development. The contrast between the node community and the PHP community cannot be overstated.