"it would be tricky to get all the rules of chess into a JS file" Check out chess.js, https://github.com/jhlywa/chess.js https://github.com/jhlywa/chess.js, it

"it would be tricky to get all the rules of chess into a JS file" Check out chess.js, https://github.com/jhlywa/chess.js https://github.com/jhlywa/chess.js, it does a pretty excellent job. The combination of chessboard.js and chess.js would result in a pretty sweet browser-based chess game.