API GetCurrentRegion

Returns a numeric ID representing the region the player is currently logged into.

regionID = GetCurrentRegion

Returns
The following region IDs are known:

Details
The value returned is deduced from the portal console variable, which may be set by the game client at launch to match the selected account region in the Battle.net desktop application. It does not necessarily indicate the region of the realm that the player is logged into, but instead the region of the Battle.net portal used to contact the login servers and provide a realm list.

This function is mostly reliable except in the case where the user modifies the portal from the login screen after having launched the game client through the Battle.net desktop application. The game client will prefer to use the login server addresses specified by the desktop application over the portal, causing a mismatch between the logged in region and what this function will report.

This function returns 1 (US) if the portal refers to an invalid region. This includes PTR and Beta servers where the portal is set to "test".