Date と getTimer()

/**
 * Copyright bkzen ( http://wonderfl.net/user/bkzen )
 * MIT License ( http://www.opensource.org/licenses/mit-license.php )
 * Downloaded from: http://wonderfl.net/c/dy3p
 */

package  
{
	import flash.display.Sprite;
	import flash.events.Event;
	import flash.text.TextField;
	import flash.text.TextFieldAutoSize;
	import flash.utils.getTimer;
	
	/**
	 * ...
	 * @author jc at bk-zen.com
	 */
	[SWF (backgroundColor = "0xFFFFFF", frameRate = "30", width = "465", height = "465")]
	public class Test2 extends Sprite
	{
		private var txt: TextField;
		private var startTimeA: uint;
		private var startTimeB: uint;
		private var count: int;
		
		public function Test2() 
		{
			if (stage) init();
			else addEventListener(Event.ADDED_TO_STAGE, init);
		}
		
		private function init(e: Event = null): void 
		{
			removeEventListener(Event.ADDED_TO_STAGE, init);
			//
			txt = new TextField();
			txt.autoSize = TextFieldAutoSize.LEFT;
			addChild(txt);
			startTimeA = new Date().getTime();
			startTimeB = getTimer();
			addEventListener(Event.ENTER_FRAME, loop);
		}
		
		private function loop(e: Event ): void 
		{
			if (count++ % 30 > 0) return;
			var ta: uint = new Date().getTime() - startTimeA, tb: uint = getTimer() - startTimeB;
			txt.text = "new Date() : " + ta + "\ngetTimer() : " + tb + "\ndiff : " + (ta - tb);
			txt.x = (stage.stageWidth - txt.width) / 2;
			txt.y = (stage.stageHeight - txt.height) / 2;
		}
		
	}

}