Holding onto code just because is a foolish notion. Sometimes approaching things with a fresh perspective is what's best - it allows you to apply what you've learned so far and actually improve not just one section of code, but the whole kit & caboodle.

This is one of the reasons you should write tests as you develop - it ensures you have a consistent baseline you can apply.

As a developer you are constantly learning & evolving. If you're not confident enough to draw a line under what you've done, step back and evaluate your position and rewrite it when needed - that's fine, but others find it an effective approach to building something bigger, better and more sustainable.

I think that this applies to the technology you're using as well.

I've been thinking about this because I'm writing an application in Rails and realized relatively recently that it would be better suited as a Node application. My motivation for using Rails was that it was what I knew the best. Luckily for me, the most time-consuming part was the front-end, not the Rails part, so I'm hoping my switch to Node will be relatively painless.