Convert as2 to as3 - actionscript-3

Question

I found a script for searching and selecting a specific text from a dynamic text box
But the problem is it is AS2
I started Flash by only studying AS3 so i have no idea on how to convert AS2 to AS3
Pls someone help me :)
finder.onRelease = function() {
Selection.setFocus("_root.textInstance");
var inputterString:String = _root.inputter
var inputLength:Number = inputterString.length;
textStart = textVar.indexOf(inputter, 0);
if (inputLength>0) {
textEnd = textStart+inputLength;
} else {
textEnd = 0;
}
if (textStart>=0) {
Selection.setSelection(textStart, textEnd);
} else {
Selection.setSelection(0, 0);
}
_root.textEnd = textEnd;
};
findNext.onRelease = function() {
Selection.setFocus("_root.textInstance");
var inputterString:String = _root.inputter;
var inputLength:Number = inputterString.length;
textStart = textVar.indexOf(inputter, _root.textEnd);
if (inputLength>0) {
textEnd = textStart+inputLength;
} else {
textEnd = 0;
}
if (textStart>=0) {
Selection.setSelection(textStart, textEnd);
} else {
Selection.setSelection(0, 0);
}
_root.textEnd = textEnd;
}

Answer 1

It's not as bad as you might think, but what are finder and findNext - buttons? These are callbacks which can be created by
finder.addEventListener(MouseEvent.MOUSE_UP, finderCallback);
// somewhere else in the code
private function finderCallback(e:MouseEvent):void {
// code here
// anything like _root.<varName> references something on the main file,
// so this just has to be something you can access in the funciton
}

Answer 2

OK, this should be it. I made some assumptions about root.textInstance and the buttons.
import flash.events.MouseEvent;
function onFinderClicked(event:MouseEvent):void{
stage.focus = root.textInstance;
root.textInstance.selectable = true;
var inputterString:String = root.inputter
var inputLength:Number = inputterString.length;
textStart = textVar.indexOf(inputter, 0);
if (inputLength>0) {
textEnd = textStart+inputLength;
} else {
textEnd = 0;
}
if (textStart>=0) {
root.textInstance.setSelection(textStart, textEnd);
} else {
root.textInstance.setSelection(0, 0);
}
root.textEnd = textEnd;
};
function onFindNextClicked(event:MouseEvent):void{
stage.focus = root.textInstance;
root.textInstance.selectable = true;
var inputterString:String = root.inputter;
var inputLength:Number = inputterString.length;
textStart = textVar.indexOf(inputter, root.textEnd);
if (inputLength>0) {
textEnd = textStart+inputLength;
} else {
textEnd = 0;
}
if (textStart>=0) {
root.textInstance.setSelection(textStart, textEnd);
} else {
root.textInstance.setSelection(0, 0);
}
root.textEnd = textEnd;
}
finder.addEventListener(MouseEvent.CLICK, onFinderClicked);
findNext.addEventListener(MouseEvent.CLICK, onFindNextClicked);