[AS3] 좌우로 움직이는 공

package
{
	import flash.display.MovieClip;
	import flash.display.Sprite;
	import flash.events.Event;

	public class Test extends Sprite
	{
		private var div:Number = 1;
	
		public function Test()
		{
			sprite.graphics.beginFill(0xff0000);
			sprite.graphics.drawCircle(0, 0, 10);
			sprite.graphics.endFill();
			
			addChild(sprite);
			sprite.y = 100;
			sprite.addEventListener(Event.ENTER_FRAME, onEnter);
		}
		
		private function onEnter(e:Event):void {
			if ( 0 < this.x < stage.stageWidth)
			{
				this.x += div * 10;
			}
			if (this.x <= 0 || this.x >=stage.stageWidth)
			{
				div = -div;
			}
		}
	}
}