Google Maps-从未定义的函数返回getPosition

Question

I have a function that initializes my google map, and within that function it calls another function which works with the geocoder for setting some markers. I create the markers in that second function.

Why is it that within that second function I can alert(marker.getPosition()) and get a latlng value. However if I do return marker.getPosition() then alert the return value of that function it displays as undefined?

Example code:

function initMap() {
    //Defined Map/Geocoder
    //Defined Array of addresses
    for (var i = 0; i < address.length; i++) {
        alert(geocodeAddress(address[i], geocoder, map)); //Alert shows undefined
    }
}
function geocodeAddress(address, geocoder, resultsMap) {
    geocoder.geocode({'address': address}, function(results, status) {
      if (status === google.maps.GeocoderStatus.OK) {
        var marker = new google.maps.Marker({
          map: resultsMap,
          position: results[0].geometry.location
        });
        alert(maker.getPosition()); //Displays latlng data
        return marker.getPosition();
      }
    });
}

Answer 1

You're just returning from your anonymous callback. You don't assign that to a variable or anything else, and your geocodeAddress function isn't returning anything to the initMap function. Try:

function geocodeAddress(address, geocoder, resultsMap) {
    return geocoder.geocode({'address': address}, function(results, status) {
      if (status === google.maps.GeocoderStatus.OK) {
        var marker = new google.maps.Marker({
          map: resultsMap,
          position: results[0].geometry.location
        });

        return marker.getPosition();
      }
    });
}

You'll need to also handle the case when you don't get a successful geocoder response.