javascript - Alert makes polyline on map display correctly! Any ideas? -

i'm reading collection of lat/long xml file , plotting markers on google map. additional join markers polylines based on "flight coordinates example".

my problem need have alert("anything") before polylines drawn, otherwise markers doesn't display on map. suspect has loading of map, have no idea how past it? have tried setinterval, created busy loop not solve problem. assistance appreciated. also, apologies if code not display in 1 block

  function initialize() {      var myoptions = {         zoom: 15,         maptypeid: google.maps.maptypeid.satellite     }     map = new google.maps.map(document.getelementbyid("map_canvas"), myoptions);      var ctalayer = new google.maps.kmllayer('http://xxx.kmz');     ctalayer.setmap(map);      var flightplancoordinates = new array()      downloadurl("incident/breadcrumb.xml" + "?dummy=" + math.random(), function (data) {         var markers = data.documentelement.getelementsbytagname("marker");          (var = 0; < markers.length; i++) {              var id = markers[i].getattribute("id");             var inspector = markers[i].getattribute("inspector");             var gpsdatetime = markers[i].getattribute("gpsdatetime");             var gpslat = markers[i].getattribute("gpslat");             var gpslong = markers[i].getattribute("gpslong");             var latlng = new google.maps.latlng(gpslat, gpslong);             var marker = createmarker(id, inspector, gpsdatetime, gpslat, gpslong, latlng);              flightplancoordinates[i] = new google.maps.latlng(gpslat, gpslong);          }     });   alert("data ready")  /// problem is, when uncomment alert polylines not show,  ///when in place works??? wtf?  var flightpath = new google.maps.polyline({         path: flightplancoordinates,         strokecolor: "#ff0000",         strokeopacity: 1.0,         strokeweight: 2     });      flightpath.setmap(map);    }   function createmarker(id, inspector, gpsdatetime, gpslat, gpslong, latlng) {     var marker = new google.maps.marker({ position: latlng, map: map });     //            var contentstring = '<div id="content" style="width:250px; height:250px; vertical-align: top; overflow: scroll;">' +     '<table border="0" cellpadding="0" cellspacing="0" style="font-size: 11px; font-family: verdana, arial, helvetica, sans-serif; width:300px;">' +     '<td >id</td><td >' + id + '</td></tr>' +   '<tr><td >inspector</td><td >' + inspector + '</td></tr>' +   '<tr><td >gpsdatetime</td><td >' + gpsdatetime + '</td></tr>' +   '<tr><td >gpslat</td><td >' + gpslat + '</td></tr>' +   '<tr><td >gpslong</td><td >' + gpslong + '</td></tr>' +    '</div>';      google.maps.event.addlistener(marker, "click", function () {         if (infowindow) infowindow.close();          infowindow = new google.maps.infowindow({ content: contentstring, maxwidth: 600 });         infowindow.open(map, marker);     });     return marker; }