NotificationType.CRITICAL needs only to only fire when file loaded is a new file - actionscript-3

Question

I have an Adobe Air desktop message board App built in Flash cs5, it loads an external ".txt" file in a dynamic text field and checks for a new file every 2 minutes. I need it to notify user with (NotificationType.CRITICAL) only if the file is new not just everytime it loads it. is it possible?
all the code in the app:
NativeApplication.nativeApplication.startAtLogin=true
stage.nativeWindow.alwaysInFront=true;
//external text file load and recheck every 2 minutes
var myInterval:uint = setInterval (loadUrl, 120000);
var loader:URLLoader = new URLLoader(new URLRequest("https://my_text_file.txt"));
loader.addEventListener(Event.COMPLETE, completeHandler);
function completeHandler(event:Event):void {
var loadedText:URLLoader = URLLoader(event.target);
if(myText_txt.htmlText!=loadedText.data){
myText_txt.htmlText = loadedText.data;
stage.nativeWindow.notifyUser(NotificationType.CRITICAL)
}else {
//do nothing
}
}
function loadUrl():void {
loader = new URLLoader(new URLRequest("https:///my_text_file.txt"));
loader.addEventListener(Event.COMPLETE, completeHandler);
}
// button control
Minimize_BTN.addEventListener(MouseEvent.CLICK, minimize);
function minimize(e:MouseEvent){
stage.nativeWindow.minimize();
}
drag_BTN.addEventListener(MouseEvent.MOUSE_DOWN, drag);
function drag(e:MouseEvent){
stage.nativeWindow.startMove();
}
stop(); //Stop on the frame you want

Answer 1

Your code might not work if the myText_txt field is modifying the loaded text (e.g., if myText_txt's condenseWhite property is set to true). A more accurate way to determine if the text has changed would be to store it in a String variable named, for example, oldText and then comparing oldText with the newly loaded text.
Here's part of your code re-written to include the oldText variable. This code is also more efficient because it instantiates some variables only once and it avoids duplicating some code:
import flash.net.URLRequest;
function completeHandler(event:Event):void
{
var newText:String = loader.data;
if(newText != oldText)
{
myText_txt.htmlText = newText;
stage.nativeWindow.notifyUser(NotificationType.CRITICAL);
oldText = newText;
}
}
function loadUrl():void
{
loader.load(req);
}
// Initialize your variables and event handlers only one time
var req:URLRequest = new URLRequest("https:///my_text_file.txt");
// Set cacheResponse to false to prevent a successful response
// from being cached.
req.cacheResponse = false;
// And don't bother checking the cache, either.
// Not necessary, but the request will execute a little faster.
req.useCache = false;
var loader:URLLoader = new URLLoader();
loader.addEventListener(Event.COMPLETE, completeHandler);
// Use oldText inside completeHandler() to determine
// whether the file's text has changed
var oldText:String = "";
var myInterval:uint = setInterval(loadUrl, 120000);
// Start loading the text right away
loadUrl();

Answer 2

Why don't you use FileReference object to find out about some properties like modificationDate and based on this verify if file is different you can also test it's size.