You would do something like that using Google API.
Please note you must include the google maps library for this to work. Google geocoder returns a lot of address components so you must make an educated guess as to which one will have the city.
"administrative_area_level_1" is usually what you are looking for but sometimes locality is the city you are after.
Anyhow - more details on google response types can be found here and here.
Below is the code that should do the trick:
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="initial-scale=1.0, user-scalable=no"/>
<meta http-equiv="content-type" content="text/html; charset=UTF-8"/>
<title>Reverse Geocoding</title>
<script type="text/javascript" src="http://maps.googleapis.com/maps/api/js?sensor=false"></script>
<script type="text/javascript">
var geocoder;
if (navigator.geolocation) {
navigator.geolocation.getCurrentPosition(successFunction, errorFunction);
}
//Get the latitude and the longitude;
function successFunction(position) {
var lat = position.coords.latitude;
var lng = position.coords.longitude;
codeLatLng(lat, lng)
}
function errorFunction(){
alert("Geocoder failed");
}
function initialize() {
geocoder = new google.maps.Geocoder();
}
function codeLatLng(lat, lng) {
var latlng = new google.maps.LatLng(lat, lng);
geocoder.geocode({'latLng': latlng}, function(results, status) {
if (status == google.maps.GeocoderStatus.OK) {
console.log(results)
if (results[1]) {
//formatted address
alert(results[0].formatted_address)
//find country name
for (var i=0; i<results[0].address_components.length; i++) {
for (var b=0;b<results[0].address_components[i].types.length;b++) {
//there are different types that might hold a city admin_area_lvl_1 usually does in come cases looking for sublocality type will be more appropriate
if (results[0].address_components[i].types[b] == "administrative_area_level_1") {
//this is the object you are looking for
city= results[0].address_components[i];
break;
}
}
}
//city data
alert(city.short_name + " " + city.long_name)
} else {
alert("No results found");
}
} else {
alert("Geocoder failed due to: " + status);
}
});
}
</script>
</head>
<body onload="initialize()">
</body>
</html>