Array Sort and Search

import flash.events.MouseEvent;
import fl.controls.TextArea;

//Declare numbersArray Array and define it as an empty array
var numbersArray:Array = [];

//Restrict the input textfields to only numbers
registerTextField.restrict = "0-9";
searchTextField.restrict = "0-9";

//Register
registerButton.addEventListener( MouseEvent.CLICK, onRegisterClick );
function onRegisterClick( event:MouseEvent ):void
{
    //If registerTextField is not empty
    if( registerTextField.length )
    {
        //Push the typed number in the numbersArray
        numbersArray.push( Number( registerTextField.text ) );
        //Update the outputTextArea
        update(registerTextField.text+" registered.");
        //Clear the registerTextField
        registerTextField.text = "";
        //Give registerTextField the focus
        stage.focus = registerTextField;
    }
};

//Function which returns a string containing all the numbers
//separated by line breaks
function parseNumbers():String
{
    var sorted:String = "";
    for(var k:String in numbersArray) sorted += String(numbersArray[k]) + "\n";
    return sorted;
};

//Ascending
ascendingButton.addEventListener( MouseEvent.CLICK, onAscendingClick );
function onAscendingClick( event:MouseEvent ):void
{
    //If numbersArray is not empty
    if(numbersArray.length)
    {
        for(var i:int = 0; i < numbersArray.length; i++)
        {
            for(var j:int = 0; j < numbersArray.length; j++)
            {
                if(numbersArray[j] > numbersArray[j+1])
                {
                    var temp:Number = numbersArray[j];
                    numbersArray[j] = numbersArray[j+1];
                    numbersArray[j+1] = temp;
                    temp = NaN;
                }
            }
        }
        //Update the TextArea
        update("Sorting in ascending order...\n"+parseNumbers());
    }
};

//Descending
descendingButton.addEventListener( MouseEvent.CLICK, onDescendingClick );
function onDescendingClick( event:MouseEvent ):void
{
    //If numbersArray is not empty
    if(numbersArray.length)
    {
        for(var i:int = 0; i < numbersArray.length; i++)
        {
            for(var j:int = 0; j < numbersArray.length; j++)
            {
                if(numbersArray[j] < numbersArray[j+1])
                {
                    var temp:Number = numbersArray[j];
                    numbersArray[j] = numbersArray[j+1];
                    numbersArray[j+1] = temp;
                    temp = NaN;
                }
            }
        }
        //Update the TextArea
        update("Sorting in descending order...\n"+parseNumbers());
    }
};

//Search
searchButton.addEventListener( MouseEvent.CLICK, onSearchClick );
function onSearchClick( event:MouseEvent ):void
{
    //If searchTextField is not empty
    if(searchTextField.length)
    {
        //Search the typed number in numbersArray and return the index
        var index:int = numbersArray.indexOf( Number( searchTextField.text ) );

        //If the number is found and the array is not empty
        if( index > -1 && numbersArray.length )
        {
            //Update the TextArea
            update("Results: " + numbersArray[ index ] + " found at index " + index);
        }
        //else, either the number was not found or the array is empty
        else
        {
            //Update the TextArea
            update("No results.");
        }
        //Clear the searchTextField
        searchTextField.text = "";
        //Give searchTextField focus
        stage.focus = searchTextField;
    }
};

//Update function
function update(string:String = null):void
{
    //If string is not empty
    if(string)
    {
        //Append the string in the TextArea
        outputTextArea.appendText( String( string ) + "\n" );
        //Update the TextArea's scrollbar position
        outputTextArea.verticalScrollPosition = outputTextArea.maxVerticalScrollPosition;
    }
};