HTML5 Game Development Insights book, in my chapter called Playing Around with the Gamepad API – you can get it from the Apress website or Amazon. I talked about the Gamepad API at the Front-Trends conference too, showing the demo game working in the browser, controlled by the gamepad.
The game itself was created using Phaser and is available to play online, you can also get it from the Firefox Marketplace and the source code was available on GitHub. Feel free to learn from it, ask questions or send feedback.