Gamepad: mapping property

The Gamepad.mapping property of the Gamepad interface returns a string indicating whether the browser has remapped the controls on the device to a known layout.

The currently supported known layouts are:

• "standard" for the standard gamepad.
• "xr-standard for the standard XR gamepad. See also XRInputSource.gamepad.

let gp = navigator.getGamepads()[0];
console.log(gp.mapping);