Trigger PHP function request when Google Maps marker is moved

When a marker is placed, I want to call a PHP function (in another file) with the latitude and longitude as input and output the result in a div on the page. So whenever the marker is moved, it updates the div with the latest result of the function.

I know I'd need JavaScript to do this but I'm not very familiar with it and any help would be appreciated.

Solution

Here is an example using jQuery to trigger a HTTP GET when a marker is added to the map and whenever it is dragged. The result of the request is placed in a div with id "outputdiv".

// create and init map (make sure to have a div element with id "map")
var map = new GMap2(document.getElementById("map"));
map.setCenter(new GLatLng(37.4419, -122.1419), 13);

// this is the marker you want to track
var marker = new GMarker(new GLatLng(37.4419, -122.1419));
map.addOverlay(marker);

// create function to be executed on add/end of drag
var changeCallback = function(latlng) {
  // do HTTP GET to execute PHP function in file, with coordinate
  // as parameter and put result in div with id "outputdiv"
  $("#outputdiv").load("test.php?latlng=" + latlng.toUrlValue());
};

// add listener triggered whenever drag of marker has ended
GEvent.addListener(marker, "dragend", changeCallback);

// explicitly call when added
changeCallback(marker.getLatLng());

Update to answer comment: The latlng parameter of the callback function is a GLatLng object where you may use lat() and lng() to retrieve the individual values. See Google Maps API reference for details.