onChange

import flash.text.TextField;
import flash.text.TextFieldType;
import flash.text.TextFormat;
import flash.events.Event;
import flash.events.KeyboardEvent;
import flash.ui.Keyboard;

// variable to store what the user types
var whatIsTyped:String = '';

// create input text field
var myInput:TextField = new TextField();
myInput.type = TextFieldType.INPUT;
myInput.width = 300;
myInput.height = 25;
myInput.x = myInput.y = 10;
myInput.defaultTextFormat = new TextFormat("Arial",18,0x0,true);
myInput.border = true;
addChild(myInput);

// add listeners, one for change, one for enter
myInput.addEventListener(Event.CHANGE, changeHandler);
stage.addEventListener(KeyboardEvent.KEY_DOWN, keyPressed);

// handle changes, adding them to var whatIsTyped
function changeHandler(e:Event):void
{
    // just update var
    whatIsTyped = myInput.text;

    // you could check the value here if you wish too
    // for every keystroke
}

// just find "ENTER"
function keyPressed(e:KeyboardEvent):void
{
    if (e.keyCode == Keyboard.ENTER)
    {
        // analyze
        trace("Analyze: " + whatIsTyped);
    }
}


// focus it, no caret seen because you need to touch a flash
// window to Activate it (win32 rule), but you can type
addEventListener(Event.ENTER_FRAME, handleEnterFrame);

function handleEnterFrame(e:Event):void
{
    removeEventListener(Event.ENTER_FRAME, handleEnterFrame);
    stage.focus = myInput;
}