The documentation seems to be implemented right now. Anyway, here is the code:
geocoder.geocode( { 'address': address, 'componentRestrictions':{'country':'GB'}}, function(results, status){ ... });
Used to limit results in a specific area. A filter consists of one or more: route, locality, administrative, postal code or country. Only results matching all filters will be returned. Filter values ββsupport the same spelling correction and partial matching methods as other geocoding requests. See the Component Filtering section of the geocoding web service for more information.
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