Many people use FlashVars as a way to send parameters to the flash movie playing in the browser. This way the parameters are imported as root level variables.
Using ActionScript 1 and 2 these variables can be accessed easily from the root level, like this: _root.parameterName. So, if you would send two parameters and their values (xmlFile=setup.xml&imageFile=picture.jpg) to the flash movie, you would access their values like this:
trace(“the xml file is: “+_root.xmlFile);
trace(“the image file is: “+_root.imageFile);
This changes when it comes to ActionScript 3. You cannot access _root.xmlFile or _root.imageFile, simply because these variables do not exist on the root level. They haven’t been declared so the compiler throws an error. The new way to access the FlashVars parameters using ActionScript 3 is to use the LoaderInfo class. Every DisplayObject contains a property called loaderInfo which is an instance of the LoaderInfo class. An object of this class contains a property called parameters. This is an object that enumerates the list of FlashVars parameters and their values. You would access these parameters like this:
var paramList:Object = this.root.loaderInfo.parameters;
trace(“the xml file is: “+paramList["xmlFile"]); // you could also use paramList.xmlFile
trace(“the image file is: “+paramList["imageFile"]); // and paramList.imageFile