Ubuntu podcast latitude script

latitude.js

(function(){
    var map = document.getElementById('map');
    var error = document.getElementById('error');
    var urlstub = "http://www.openstreetmap.org/export/embed.html?";

    function updateMap() {
	var request = new XMLHttpRequest();
	request.open('GET', 'latitudefile.txt', true);

	request.onload = function() {
	    if (request.status >= 200 && request.status < 400) {
		// Success!
		var data = JSON.parse(request.responseText);
		// Get the co-ordinates
		var lat = parseFloat(data.data[1][0]);
		var lon = parseFloat(data.data[2][0]);
		var scale = 0.05;
		if (lat == 0 && lon == 0) {
		    // If we don't have a position, default to a map of the whole UK.
		    lat = 54;
		    lon = -0.45;
		    scale = 2;
		    error.style.display = 'block';
		} else {
		    error.style.display = 'none';
		}
		// If we do have a postion, calculate the top and bottom of the map.
		var toplat = lat - scale;
		var toplon = lon - scale;
		var bottomlat = lat + scale;
		var bottomlon = lon + scale;
		// Create the URL
		var url = urlstub + "bbox=" + toplon + "," + toplat + "," + bottomlon + "," + bottomlat 
		    + "&layer=mapnik"
		    
		// Add the marker
		if (scale == 0.05) {
		    url += "&marker=" + lat + "," + lon;
		}
		map.setAttribute('src', url);
	    }
	};
	request.send();
    }

    updateMap();
    setInterval(updateMap, 30000);

})();