The files are stored in folders corresponding to the year of the challenge. They're named after the day and the puzzle number for that day (ie: _1 is puzzle 1 and _2 is puzzle 2).
Each one of them is designed to execute directly in the browser developer console with the input data file loaded as the main page.
Feel free to crib from these and use them as a learning exercise, and I'm happy to talk about them to anyone interested in a fuller explanation - just message me.
I make no warranties about the quality of the code - it's all going to be pretty rough and ready...