'Sort By' function for long section pages in Actinic - part 1

This is something I have just completed for MumStuff and it works a treat! There were lots of little quirks within Actinic that had to be overcome and I thought I'd share how I achieved it. I'm also making the javascript functions available for free, but I'm not offering any guarantees that they will work with your site, so be prepared to tinker if that's your thing!

So, to start with, you can download the javascript file here: download
This contains lots of comments that hopefully start to explain how it works. I'll post Part 2 soon with some more details as to how to set up Actinic.