HTML5

Geolocation with HTML5 is used to locate a user's position, and it's much more accurate for devices with GPS, like smartphones. Internet Explorer 9+, Firefox, Chrome, Safari and Opera support Geolocation. Since this can compromise user privacy, the position is not available unless the user approves it.

Controllo abilitazione

if(navigator.geolocation){
  alert('Geolocation enabled!');  
} else {
  alert('Geolocation NOT enabled!');
}

Ottenere le coordinate geografiche

var x = document.getElementById("demo");
function getLocation() {
    if (navigator.geolocation) {
        navigator.geolocation.getCurrentPosition(showPosition);
    } else {
        x.innerHTML = "Your browser doesn't support geo location";
    }
}
function showPosition(position) {
    x.innerHTML = "Latitude: " + position.coords.latitude + 
    "Longitude: " + position.coords.longitude; 
}

getLocation();