professional_javascript_for_web/ch25/GeolocationExample01.htm

<!DOCTYPE html>
<html>
<head>
    <title>Geolocation Example</title>
</head>
<body>
    <p>This page is a demonstration of the Geolocation API. This works in the latest versions of all major browsers, but you may need to place this file on a web server to get it to work.</p>
    <script>
        window.onload = function(){
            document.getElementById("geo-btn").onclick = function(){
                navigator.geolocation.getCurrentPosition(function(position){
                    document.getElementById("output").innerHTML = "Latitude is " + position.coords.latitude +
                        "<br>Longitude is " + position.coords.longitude;
                }, function(error){
                    document.getElementById("output").innerHTML = error.message || "An error occurred while trying to get location.";
                });
            };
        };
        
    </script>
    
    <p><script>document.write(navigator.geolocation ? "Your browser supports the Geolocation API." : "Your browser does not support the Geolocation API.");</script></p>
    <input type="button" value="Get Location" id="geo-btn">
    <div id="output"></div>
</body>
</html>