Geocoding Addresses with Google Maps API

G
Published in: Google Maps - JavaScript

The reverse geocoding feature of Google Maps API lets you convert latitude and longitude into a physical address. Here’s a snippet of code that implements address lookup in Google Maps using JavaScript.

//Initialize Global Variables
var adUnit;
var marker;
var infoWindow;
var geocoder;
var map = null;
var lat;
var lon;

function initialize() {

    var mapOptions = {
        zoom: 16,
        mapTypeId: google.maps.MapTypeId.ROADMAP,
        streetViewControl: false,
        panControl: false,
        mapTypeControl: true,
        mapTypeControlOptions: {
            style: google.maps.MapTypeControlStyle.HORIZONTAL_BAR,
            position: google.maps.ControlPosition.BOTTOM_CENTER
        },
        zoomControl: true,
        zoomControlOptions: {
            style: google.maps.ZoomControlStyle.SMALL,
            position: google.maps.ControlPosition.LEFT_CENTER
        }
    };

    map = new google.maps.Map(document.getElementById('map'), mapOptions);
    var adUnitDiv = document.createElement('div');
    var adsense = "ca-pub-1234";

    // Add a Google AdSense unit
    var adUnitOptions = {
        format: google.maps.adsense.AdFormat.BUTTON,
        position: google.maps.ControlPosition.RIGHT_BOTTOM,
        publisherId: adsense,
        map: map,
        visible: true
    };

    var adUnit = new google.maps.adsense.AdUnit(adUnitDiv, adUnitOptions);

    lat = 37.41954708018655;
    lon = -122.08398342132568;

    // Determine your initial location through GPS
    if (navigator.geolocation) {
        navigator.geolocation.getCurrentPosition(function(position) {
            lat = position.coords.latitude;
            lon = position.coords.longitude;
        });
    }

    var latLng = new google.maps.LatLng(lat, lon);
    map.setCenter(latLng);
    marker = new google.maps.Marker({
        position: latLng,
        title: 'Drag this pin to another location',
        animation: google.maps.Animation.DROP,
        map: map,
        draggable: true
    });

    infoWindow = new google.maps.InfoWindow({
        content: "<div class='place'>Drag this pin anywhere on the Google Map to know the approximate address of that point.</div>"
    });

    infoWindow.open(map, marker);

    geocoder = new google.maps.Geocoder();

    //Update postal address when the marker is dragged
    google.maps.event.addListener(marker, 'dragend', function() {
        geocoder.geocode({latLng: marker.getPosition()}, function(responses) {
            if (responses && responses.length > 0) {
                infoWindow.setContent(
                "<div class='place'>" + responses[0].formatted_address
                + "<br /> <small>"
                + "Latitude: " + marker.getPosition().lat() + "<br>"
                + "Longitude: " + marker.getPosition().lng() + "</small></div>"
                );
                infoWindow.open(map, marker);
            } else {
                alert('Error: Google Maps could not determine the address of this location.');
            }
        });
        map.panTo(marker.getPosition());
    });

    // Close the marker window when being dragged
    google.maps.event.addListener(marker, 'dragstart', function() {
        infoWindow.close(map, marker);
    });
}

google.maps.event.addDomListener(window, 'load', initialize);

// Search for an address on Google Maps
function showAddress(address) {
    if (geocoder) {
        geocoder.geocode({'address': address}, function(results, status) {
            if (status == google.maps.GeocoderStatus.OK) {

                // For accurate addresses, the type is ROOFTOP else APPROXIMATE
                if (results[0].geometry.location_type == "ROOFTOP")
                    map.setZoom(18);
                else
                    map.setZoom(14);
                map.setCenter(results[0].geometry.location);
                marker.setPosition(results[0].geometry.location);
                infoWindow.open(map, marker);
            } else {
                alert("Error: " + address + " cannot be found on Google Maps.");
            }
        });
    }
}
Published in: Google Maps - JavaScript

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Amit Agarwal

Amit Agarwal is a Google Developer Expert in GSuite and Google Apps Script. He holds an engineering degree in Computer Science (I.I.T.) and is the first professional blogger in India. Read more on Lifehacker and YourStory

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