HTML5 Geolocation implementation

Question

I have a list of areas and lattitude/longitude which I'm asking the user to select their location when they hit my site. I'd like to have their location prefilled using HTML5's geolocation if possible, but I'm not exactly sure the best way to do that. There seems to be a lack of tutorials on the web, at least from what I can find. Has anyone done this? Do you know of a good tutorial/resource?

update

If I have coordinates of bunch of cities, how can I use javascript to determine the closest location?

Answer 1

Try this example:

window.onload = function(){
    if(navigator.geolocation)
        navigator.geolocation.getCurrentPosition(handleGetCurrentPosition, onError);
}

function handleGetCurrentPosition(location){

    location.coords.latitude;
    location.coords.longitude;
}
function onError(){...}

Go here for a larger demo. http://od-eon.com/labs/geolocation/