why doesn't this code detect diagonal motion? - actionscript-3

Question

"player" is an object that moves up , down , left and right when I press on arrow keys.
"player" doesn't move diagonally when I press up and left keys together or any other couple of keys.
I'm using Adobe flash CS5 and action script 3 ( As3 ), Would you tell me what the solution is ?
stage.addEventListener(KeyboardEvent.KEY_DOWN, detectText);
function detectText(myevent:KeyboardEvent):void {
var up:Boolean = false;
var down:Boolean = false;
var left:Boolean = false;
var right:Boolean = false;
var speedOfplayer:Number = 5 ;
if (myevent.keyCode==39){
right = true ;
}
if (myevent.keyCode==37){
left = true ;
}
if (myevent.keyCode==38){
up = true ;
}
if (myevent.keyCode==40){
down = true ;
}
// if(right is true and left is not true)
if( right && !left ) {
player.x = player.x + speedOfplayer;
}
// if(up is true and down is not true)
if( up && !down ) {
player.y = player.y - speedOfplayer;
}
// if(down is true and up is not true)
if( down && !up ) {
player.y = player.y + speedOfplayer;
}
// if(down is true and up is not true)
if( left && !right ) {
player.x = player.x - speedOfplayer;
}
// Move diagonally
if( left && up && !right && !down ) {
player.y = player.y - speedOfplayer;
player.x = player.x - speedOfplayer;
}
if( right && up && !left && !down ) {
player.x = player.x + speedOfplayer;
player.y = player.y - speedOfplayer;
}
if( left && down && !right && !up ) {
player.x = player.x - speedOfplayer;
player.y = player.y - speedOfplayer;
}
if( right && down && !left && !up ) {
player.x = player.x + speedOfplayer;
player.y = player.y + speedOfplayer;
}

Answer 1

You may be overcomplicating things. This can be done in the following way. What is happening to the KEY_DOWN listener is that it will report the last key pressed. So you need a ENTER_FRAME listener to move the object. And because ENTER_FRAME will keep calling the function provided you need to capture if a key is released to reset the speed of the player to 0.
stage.addEventListener(KeyboardEvent.KEY_DOWN, onKeyDown);
stage.addEventListener(KeyboardEvent.KEY_UP, onKeyUp);
stage.addEventListener(Event.ENTER_FRAME, onTick);
var speedX:uint = 0;
var speedY:uint = 0;
function onKeyDown(event:KeyboardEvent):void {
var key:uint= event.keyCode;
if (key == Keyboard.UP) {
speedY = -5;
}
if (key == Keyboard.DOWN) {
speedY = 5;
}
if (key == Keyboard.LEFT) {
speedX = -5;
}
if (key == Keyboard.RIGHT) {
speedX = 5;
}
}
function onKeyUp(event:KeyboardEvent):void {
var key:uint= event.keyCode;
if (key == Keyboard.UP || key == Keyboard.DOWN) {
speedY = 0;
}
if (key == Keyboard.LEFT || key == Keyboard.RIGHT) {
speedX = 0;
}
}
function onTick(event:Event):void {
player.x += speedX;
player.y += speedY;
}