The first few examples do not appear to be Javascript. It's implemented in Javascript, yes, but Javascript does not have the BASIC-like functionality that is used in the examples.

Back in 2009, I did something very similar with one of the 1997 Kasparov vs. Deep Blue games.

One difference is that I used a chess engine, and made the search tree audible, so you can hear the chess computer "thinking". Here's my original blog article: http://www.krazydad.com/blog/2009/05/musical-chess/ and here's video from the concert: http://www.youtube.com/watch?v=42G6P0b72Gk