Window.ongamepaddisconnected

The ongamepaddisconnected property of the Window interface represents an event handler that will run when a gamepad is disconnected (when the gamepaddisconnected event fires).

The event object is of type GamepadEvent.

window.ongamepaddisconnected = function() { ... };

window.ongamepaddisconnected = function() {
  // A gamepad has been disconnected
};