Определить края сцены

var SPEED:Number = 5;

function moveLeft():Void {
var leftWall:Number = 0;
if(target._x > leftWall) {
target._x -= SPEED;
}else {
target._x = leftWall;
}
}

function moveRight():Void {
var rightWall:Number = Stage.width - target._width;
if(target._x < rightWall) {
target._x += SPEED;
}else {
target._x = rightWall
}
}

function moveUp():Void {
var topWall:Number = 0
if(target._y > topWall) {
target._y -= SPEED;
}else {
target._y = topWall;
}
}

function moveDown():Void {
var bottomWall:Number = Stage.height - target._height;
if(target._y < bottomWall) {
target._y += SPEED;
}else {
target._y = bottomWall;
}
}