如何使用谷歌地图检测当前位置？

Question

我正在使用thr API Google Maps。我提出了特定的coord。我是代码：

$scope.init = function() {

        var latlon = new google.maps.LatLng(47.1312627, 27.5643737);
        mapCanvas = document.getElementById('mapholder');
        mapCanvas.style.height = '860px';


        map = new google.maps.Map(document.getElementById('mapholder'), {
            mapTypeId: google.maps.MapTypeId.ROADMAP,
            center: latlon,
            zoom: 15
        });

        var currentMarker = new google.maps.Marker({
            map: map,
            position: latlon,
            icon: 'img/Standing Man-48.png',
            title: 'Current Location'
        });
         var myinfowindow = new google.maps.InfoWindow({
            content: 'You are here'
          });

            myinfowindow.open(map, currentMarker);


        if ($scope.choice != '') {
            var request = {
                location: latlon,
                radius: 7000,
                //  query: 'atm'
                types: [$scope.choice]
            };
            infowindow = new google.maps.InfoWindow();
            var service = new google.maps.places.PlacesService(map);
            service.nearbySearch(request, callback);

        }

    }

我也在搜索现在可以使用的neaby地方。（$ scope.choice在用户选择项目时自动更新） 如何检测用户的当前位置并将该部分放在附近？

谢谢