I've been working on and off a solo project for three years.
Definitely get out into any kind of community, actually for me I've found non-computer clubs, friends, neighbours, church, playing music really help keep things balanced.
Feedback on the project itself is harder to find, especially since I've picked a fairly niche area (probably everyone does), but on occasion tech nerds ask me how I'm getting on. Blogging and online discussion focused on the area you are working in would be the best/easiest way to get feedback, though in person is often more ... encouraging :-)
As to keeping the code clean, I'd recommend books like "Pragmatic Programmer", "Clean Code", "The Clean Coder", "Refactoring", "Test Driven Development: By Example" - I use tests to keep the code working, refactoring to keep things clean, and git / git hosting sites to keep it all organized and backed up.
I also use task/bug tracking software (Jira + Structure) to write down absolutely everything I find annoying, and to break down tasks into very small chunks (a test/code/refactor/commit iteration is about 30 minutes on average, I checked a while back). I don't necessarily fix the all the things, but it keeps them out of my head, and that means I can concentrate on the next step.
The other thing I was advised to do was to get part time contract work, so I've found a great company that let me work flexible hours together with other engineers on a completely different project. I've been able to work three day weeks sometimes. They were unusual in allowing me to retain all rights to my own work.
Fun story: Amazon, Google and Facebook keep soliciting me to join them. Once, I responded by email "so can you match my current three day working week, allow me to retain all IP rights to my own work?". The answer was "wow, err, yeah, that's a deal we can't match."
Thanks for the book recommendations! Definitely going to check those out, hopefully the library has some of them. Are they language agnostic? Any you know of that are JS specific?
Bug tracking software is a great suggestion. I've started doing that recently as well. I didn't see the value in it for a long time being the only developer, but it's helped me keep track of things and report progress back to the rest of the company much more easily.
Fairly language agnostic, from memory most of those books tend to concentrate on concepts, though they use Java or perhaps C++. I've seen copies in larger libraries and book stores.
I'd suggest looking at O'Reilly Learning / Safari - you get access to a whole heap of books (40,000 last time I looked), videos and all sorts of other things. It is $400 a year. Personally I decided books are so important, and was spending more each year (most books are $60 - $120 each), so I subscribed years ago and have never since thought about the cost.
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