The UI Events spec standardizes the key and code associated with each KeyboardEvent.
key describes the input character and depends on the logical layout while
code describes the physical key and depends on the physical layout.
There's an experimental spec for getting the logical layout (Keyboard.getLayoutMap()), but no way to get the physical layout. Nevertheless, the UI Events spec is based on a set of reference keyboards and able to accommodate arbitrary keyboards.
This library encodes the reference keyboards as Javascript objects. This allows users to construct a visual representation of the keyboard and map codes to physical positions. See the demo.