Flash AS3 Player Control with Arrow Keys Code

import flash.events.Event;
import flash.events.KeyboardEvent;
 
stage.addEventListener(KeyboardEvent.KEY_DOWN, onKeyPressed);
stage.addEventListener(KeyboardEvent.KEY_UP, onKeyReleased);
addEventListener(Event.ENTER_FRAME, gameLoop);
 
var playerSpeed = 2;
player.x = 400;
 
var isLeftKeyDown = false;
var isRightKeyDown = false;
var isUpKeyDown = false;
var isDownKeyDown = false;
 
function onKeyPressed(evt:KeyboardEvent) {
 
 if(evt.keyCode == Keyboard.LEFT) {
     isLeftKeyDown = true;
 }
 
 if(evt.keyCode == Keyboard.RIGHT) {
     isRightKeyDown = true;
 }
 
 if(evt.keyCode == Keyboard.UP) {
     isUpKeyDown = true;
 }
 
 if(evt.keyCode == Keyboard.DOWN) {
     isDownKeyDown = true;
 }
}
 
function onKeyReleased(evt:KeyboardEvent) {
 
 if(evt.keyCode == Keyboard.LEFT) {
     isLeftKeyDown = false;
 }
 
 if(evt.keyCode == Keyboard.RIGHT) {
     isRightKeyDown = false;
 }
 
 if(evt.keyCode == Keyboard.UP) {
     isUpKeyDown = false;
 }
 
 if(evt.keyCode == Keyboard.DOWN) {
     isDownKeyDown = false;
 }
}
 
function gameLoop(evt:Event) {
 if(isLeftKeyDown == true) {
     player.x-=playerSpeed;
 }
 
 if(isRightKeyDown == true) {
     player.x+=playerSpeed;
 }
 
 if(isUpKeyDown == true) {
     player.y-=playerSpeed;
 }
 
 if(isDownKeyDown == true) {
     player.y+=playerSpeed;
 }
}