window.addEventListener("gamepadconnected", function(e) {

   var gamepad = e.gamepad;

   var index = gamepad.index;

   var id = gamepad.id;

   var nbButtons = gamepad.buttons.length;

   var nbAxes = gamepad.axes.length;

   console.log("Gamepad No " + index +

               ", with id " + id + " is connected. It has " +

               nbButtons + " buttons and " +

               nbAxes + " axes");

});

​

window.addEventListener("gamepaddisconnected", function(e) {

   var gamepad = e.gamepad;

   var index = gamepad.index;

   console.log("Gamepad No " + index + " has been disconnected");

});