geolocation HTML GEOLOCATION API - HANDLING ERRORS QUESTION

[noetherian]

Hello,

A question about this code: 

function showError(error) {
  switch(error.code) {
    case error.PERMISSION_DENIED:
      x.innerHTML = "User denied the request for Geolocation."
      break;
    case error.POSITION_UNAVAILABLE:
      x.innerHTML = "Location information is unavailable."
      break;
    case error.TIMEOUT:
      x.innerHTML = "The request to get user location timed out."
      break;
    case error.UNKNOWN_ERROR:
      x.innerHTML = "An unknown error occurred."
      break;
  }
}

According to the Geolocation spec. , there are 3 constants representing errors:

PERMISSION_DENIED,  POSITION_UNAVAILABLE, and TIMEOUT. It doesn't mention UNKNOWN_ERROR

So I don't understand how the case of error.UNKNOWN_ERROR fits in the code.

Was it predefined anywhere else? what will it return? and how can I cause an (intentional) unknown error to trigger this case?

Thank you very much for any assistance. 

[noetherian]

I think I got it. 

By just removing the first three breaks, I triggered the unknown error case and could see the result.

So to answer my own questions:

Was it predefined anywhere else? No, and also I understand that it didn't need to be.

What will it return?   error.UNKNOWN_ERROR simply returns 'undefined' and it's not a problem at all.

How can I cause an (intentional) unknown error to trigger this case?   I didn't need to cause a specific run-time unknown error to trigger the last case ,

I just removed the first three breaks and the last case was triggered, so I could see that error.UNKNOWN_ERROR  returns 'undefined' and realize that it is just fine.

"An unknown error occurred" message is printed on the page as it should be. 

Thanks!