Navigator.geolocation read-only property returns a
Geolocation object that gives Web content access to the location of the device. This allows a Web site or app to offer customized results based on the user's location.
Note: For security reasons, when a web page tries to access location information, the user is notified and asked to grant permission. Be aware that each browser has its own policies and methods for requesting this permission.
geo = navigator.geolocation
The definition of 'Navigator.geolocation' in that specification.