Check to see if a loader already contains an image

1

Hi, I hope you can help me on a problem that has left me stuck for a couple of days.

I have created a photo gallery, following this tutorial:
http://www.republicofcode.com/tutorials/flash/as3gridgallery/index.php

However I want the user to be able to click a thumbnail, which triggers a function to unload the previous image, and then reload the selected image.

function callFull(e:MouseEvent):void{    
var full_loader:Loader = new Loader();
var full_url = my_images[e.target.name].@FULL;
full_loader.load(new URLRequest(full_url));
full_loader.contentLoaderInfo.addEventListener(Event.INIT, fullLoaded);
}

function fullLoaded(e:Event):void{    
var my_loader:Loader = Loader(e.target.loader);
addChild(my_loader);
my_loader.x = 300;
my_loader.y = 80;        
my_loader.addEventListener(MouseEvent.CLICK,removeFull); // Removes image when large pic is clicked
}

I’ve been told to use

if ( hasChild( my_loader )) return;

, however this gave me an error as hasChild isn’t recognised in AS.

Any solutions to my problem? Thanks.