AS3 event.target and var - actionscript-3

Question

I have an editable text field (c) in a movieClip, well 3 movielips like this actually named a1, a2 and a3. Movieclips are already on stage. The path to text field in each MC is mc.a1.c, mc.a2.c and mc.a3.c
The initial value for each textfield is set by XML which is also stored in variables with the same names and the movieclip(a1,a2,a3). If the user updates a textfield a CHANGE event listener triggers checkValue function. If the value is greater than my maxValue I want my function to return the text field to its original value and give the user an error message. So if textfield c in mc.a1.c is updated, I'm currently taking the name of its parent (a1) and then trying to reference the variable with the same name so that textfield c will be returned to the initial value held in var a1 (I'll only know which var to reference once a textfield update has been attempted.. hope that makes sense)
I've tried several things but always end up with the variable name, and not its value in the textfield. So, for now I've reverted to populating the field with 0 until I can find an answer.
example code:
aH.t1 is the predefined max value
function chngTh(event:Event):void{
var thR:String = String(event.target.parent.name.substring(0,1));
if (thR =="a"&&thN>int(aH.t1.text)){
event.target.text = 0; //I want the reference var a(x)and have its value in the text field
aH.errorMsg.text = "The number cannot be greater than 10 so the original value has been restored";
}
}
As you can probably tell my my code, I'm not a developer and I've already looked here in search of but can't seem to get grasp it...Is it me?
reference variable AS3
AS3: Using string as variable
Is what I'm trying to do achiveable in AS3?
Thanks to guidance from dene the solution looks like this:
function chngTh(event:Event):void{
var thR:String = String(event.target.parent.name.substring(0,1));
var thN:int = (event.target.text);
var thov:int = root[event.target.parent.name];
if (thR =="a"&&thN>int(aH.thrsh.t1.text)){
event.target.text = thov;
aH.errorMsg.text = hclbl[12];
}
}

Answer 1

Use event.target in the listener function to reference the text field that changed:
var maxValue = 5;
myTextField.addEventListener(Event.CHANGE, textListener);
function textListener(event:Event)
{
var tf = event.target as TextField;
var currentValue = parseFloat(tf.text);
if (currentValue > maxValue) {
tf.text = getOriginalValue(tf);
}
}
function getOriginalValue(tf:TextField) : Number
{
// Assuming the textfield's parent is named "a" + number (eg. a1, a2 etc.)
// Get the number of the parent by ignoring the character at index 0
var parentName = tf.parent.name;
var parentNumber = parentName.substring(1);
// Now you can use parentNumber to access the associated variable (a1, a2, etc)
// Assuming these variables are defined on the root (main timeline).
var originalValue = root["a" + parentNumber]
// If the variables are stored as Strings, this line is needed to convert it to a Number type
originalValue = parseFloat(originalValue)
return originalValue;
}