Question

please have a look at the following code. When the value of i == 0 the alert 1 prints variable values as per logic. But if I try to print values (alert 2), it just says “undefined, undefined”. My question is what changes I’ll have to make to get the values printed in second alert (Alert 2) same as per alert 1?

var testPoint = [];

function load() {
  if (GBrowserIsCompatible()) {
    map = new GMap2(document.getElementById("map_canvas"));
    map.addControl(new GSmallMapControl());
    map.addControl(new GMapTypeControl());
    map.setCenter(new GLatLng(52.5271463402545, -1.50573921491311), 8, G_HYBRID_MAP);

    GDownloadUrl("controllers/gmap_genxml2.php", function(data) {
      var xml = GXml.parse(data);
      var markers = xml.documentElement.getElementsByTagName("marker");
      for (var i = 0; i < markers.length; i++) {
        if(i == 0) {
            testPoint["lat"] = parseFloat(markers[i].getAttribute("lat"));
            testPoint["lng"] = parseFloat(markers[i].getAttribute("lng"));

            /********* ALERT 1 ***********/
            alert(testPoint["lat"]+" "+testPoint["lng"]);
            /********* ALERT 1 End ***********/
        }
        var name = markers[i].getAttribute("name");
        var address = markers[i].getAttribute("address");
        var type = markers[i].getAttribute("type");
        var point = new GLatLng(parseFloat(markers[i].getAttribute("lat")),
                                parseFloat(markers[i].getAttribute("lng")));
        var marker = createMarker(point, name, address, type);
        map.addOverlay(marker);
      }
    });

    /********* ALERT 2 ******************/
    alert(testPoint["lat"]+" "+testPoint["lng"]);
    /********* ALERT 2 Start ***********/
  }
}

Thank you for your help.
DeeJay

Answer 1

    testPoint = [];

    // This global var is introduced to mark that testPoint values are not yet loaded.
    var isLoaded = false;

    function load() {

    if (GBrowserIsCompatible()) {
        map = new GMap2(document.getElementById("map_canvas"));
        map.addControl(new GSmallMapControl());
        map.addControl(new GMapTypeControl());
        map.setCenter(new GLatLng(52.5271463402545, -1.50573921491311), 8, G_HYBRID_MAP);

    GDownloadUrl("controllers/gmap_genxml2.php", function(data) {
      var xml = GXml.parse(data);
      var markers = xml.documentElement.getElementsByTagName("marker");
      for (var i = 0; i < markers.length; i++) {
        if(i == 0) {
                testPoint["lat"] = parseFloat(markers[i].getAttribute("lat"));
                testPoint["lng"] = parseFloat(markers[i].getAttribute("lng"));

                /********* ALERT 1 ***********/
                alert(testPoint["lat"]+" "+testPoint["lng"]);
                /********* ALERT 1 End ***********/

                // Set it to true to indicate that testPoint array is already loaded.
                isLoaded = true;
        }
        var name = markers[i].getAttribute("name");
        var address = markers[i].getAttribute("address");
        var type = markers[i].getAttribute("type");
        var point = new GLatLng(parseFloat(markers[i].getAttribute("lat")),
                                parseFloat(markers[i].getAttribute("lng")));
        var marker = createMarker(point, name, address, type);
        map.addOverlay(marker);
      }
    });

    /********* ALERT 2 ******************/
     // Try to alert testPoint each 0.5 sec until we can successfully do it.
     function alert2() {
         // if testPoint is loaded - then alert it, if not then try in 0.5 sec.
         if (isLoaded) {
              alert(testPoint["lat"]+" "+testPoint["lng"])
         } else {
              setTimeout(alert2, 500);
         }
     };

     alert2();
    /********* ALERT 2 Start ***********/
  }
}