Cordova/Ionic httpd server plugin - url not visible - angularjs

Question

i have a problem with Angular controller in my Ionic/Cordova project.
Can someone explain me why url which i get in line 25: $scope.serverURL=url;
isn't visible in line 63 alert($scope.serverURL); (it return null)?
Here is my controller:
var app = angular.module('iremotee');
app.controller('StreamingController', function(ConnectSdkService, $scope, $rootScope, $state, Camera) {
var options = {
quality: 100,
destinationType: 0,
sourceType: 0,
mediaType: 2
};
$scope.currentFile = null;
$scope.httpd = null;
$scope.serverURL = null;
alert($scope.serverURL + "!!!");
$scope.createHttpd = function() {
$scope.httpd = (cordova && cordova.plugins && cordova.plugins.CorHttpd) ? cordova.plugins.CorHttpd : null;
};
$scope.startMediaServer = function() {
if ($scope.httpd) {
// before start, check whether its up or not
$scope.httpd.getURL(function(url) {
if (url.length > 0) {
$scope.serverURL = url;
alert($scope.serverURL);
} else {
$scope.httpd.startServer({
'www_root': '/',
'port': 8080,
'localhost_only': false
}, function(url) {
$scope.serverURL = url;
alert($scope.serverURL);
}, function(error) {});
}
});
} else {}
};
$scope.stopServer = function() {
if ($scope.httpd) {
$scope.httpd.stopServer(function() {}, function(error) {});
}
};
$scope.getMedia = function() {
$state.go('mainmenu');
};
ionic.Platform.ready(function() {
$scope.createHttpd();
$scope.startMediaServer();
});
$scope.getFile = function() {
alert($scope.serverURL);
Camera.getFromMemory(options).then(function(URI) {
if (URI.indexOf("file://") == -1) {
URI = "file://" + URI;
}
window.resolveLocalFileSystemURL(URI, function(fileEntry) {
var URI = fileEntry.toURL();
var str = URI;
str = str.replace("file:///storage/emulated/0/", "/sdcard/");
str = str.replace("file:///storage/emulated/0/", "/sdcard1/");
str = str.replace("file:///storage", "");
Camera.currentURI = str;
alert(Camera.currentURI);
$scope.currentFile = Camera.currentURI;
}); //resolveLocalFileSystemURL-END
}, function(err) {
alert(err);
}); //getFromMemory-END
}; //getFile-END
$scope.$on('$destroy', function() {
$scope.stopServer();
});
});