Add scrolls to textboxes with AS3

// here we declare a request to the content text file and name it externalReq.
var externalReq:URLRequest = new URLRequest("content.txt");

// Here we declare a variable for the URLLoader.
var externalLoad:URLLoader = new URLLoader();

// here we set the externalLoader to load in the text file from the URLRequest variable.
externalLoad.load(externalReq);

// Now before we just set the text fields text property equal to the text content, we need to be sure that the text is finished loading, so we add an eventlistener.
// this eventlistener will listen and call a function when the text is done loading, and the function we call is textReady.
externalLoad.addEventListener(Event.COMPLETE, textReady);

// here is the function to handle the text, we set the text_f.text property equal to event.target.data (the event is refering to the externalLoad.data).
function textReady(event:Event):void {
    text_f.text = event.target.data;
}

// Here is the last and new part, here we add two eventlisteners, to listen to when the up and down arrows are clicked, then it will call the two functions "scrollUp" and "scrollDown".
up_btn.addEventListener(MouseEvent.CLICK, scrollUp);
down_btn.addEventListener(MouseEvent.CLICK, scrollDown);

// the function is quite simple and except the outer function part, it acturlly only contains one line of code to scroll.
// its the scrollV method. and here we subtract 1 from its original value by using the --
function scrollUp(Event:MouseEvent):void {
    text_f.scrollV --;
}

//Here we make a function to handle the down button, and here we add one to the original scrollV value by using ++
function scrollDown(Event:MouseEvent):void {
    text_f.scrollV ++;
}