HTML5 Samples

Step one

You can use standard object testing to determine if the browser supports GeoLocation.

<script>
    /**
    * This function is the callback which is passed the result from the .getCurrentPosition()
    * function. The pos argument can contain more information than just the latitude/longitude,
    * such as altitude, accuracy and speed information.
    *
    * @param object pos The result from the getCurrentPosition() call
    */
    function myCallback(pos)
    {
        var myLatitude  = pos.latitude;
        var myLongitude = pos.longitude;
    }

    /**
    * Test for GeoLocation support and make the call
    */
    if (navigator.geolocation) {
        navigator.geolocation.getCurrentPosition(myCallback);
    } else {
        alert("Sorry, your browser doesn't appear to support GeoLocation");
    }

</script>

Step two

Once you have tested for it, we can then retrieve the position using the getCurrentPosition() method. You pass this method a callback function which you define. This callback function is given an object (if successful), with various properties:

• latitude


• longitude


• altitude (optional)


• accuracy


• altitudeAccuracy (optional)


• heading (optional)


• speed (optional)


• timestamp

more  detail go to

http://www.html5samples.com/2010/04/html5-geolocation-introduction/