Data communication between MFC and JavaScript for a Google Maps application

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Javascript

Hi all,

I'm new to JavaScript and Google Maps API. I got some problems but I cannot find out the reason. Hope someone can help me.

What I tried to do:
I'm trying to develop an application in MFC (Visual Studio 2005) with a html dialog showing a Google map. I will send location data from the MFC application to a JS function to calculate directions. Another JS function will return the number of routes and steps in the GDirection object. The result will be sent back as a message string.

The problem I encountered:
If I open the html file using IE and manually input the location data and use alert function to show the message, everything works well. I can send the location data from MFC to JS. However, after that, I cannot get the route number back... It always returns the number as "undefined".

Some codes:

function initialize() {
      if (GBrowserIsCompatible()) {      
        map = new GMap2(document.getElementById("map_canvas"));
        gdir = new GDirections(map, document.getElementById("directions"));
        GEvent.addListener(gdir, "load", onGDirectionsLoad);
        GEvent.addListener(gdir, "error", handleErrors);
      }
    }
    function UpdateGPS(ar) // this is where MFC send the location data to JS
    {
      var a = new VBArray(ar);
      var b = a.toArray();
      rExp = /(\w|\s)*[^@]/ig;
      var res = b[0].match(rExp);	// Name @ size @ free_space
      lan = parseInt(res[1]) / 1000000;
      lon = parseInt(res[2]) / 1000000;	
      str = lan + "," + lon;		
      setDirections(str, "1.300983,103.772704");
    } 
	
    function getRoute() // this is where JS should send information back to MFC
    {
      return message;
    }
    function setDirections(fromAddress, toAddress) 
    {
      gdir.load("from: " + fromAddress + " to: " + toAddress, {getPolyline:true, getSteps:true, travelMode:G_TRAVEL_MODE_WALKING});
    }
    function onGDirectionsLoad()
    {
      n_route = gdir.getNumRoutes();
      message = str + ". we have " + n_route + " route.";	
      alert(message);
    }

Can someone help me here? Thanks a lot!