A year or so ago I spent a few hours writing an IPv4 subnet calculator in javascript. I didn’t have any real goal, just a desire to play with javascript. I promptly forgot about it. Then a month or so ago I found it again and dusted it back off. I had a lot of fun rewriting it and then… forgot about it again.
After remembering it yet again last night, I decided enough was enough, filed the roughest edges off of it, and posted it: