ถามเกี่ยวกับ การใช้ Time และอื่นๆ เข้ามาดูทีครับ

<script>
var offset=new Date();
var  startTime = 5*1000 ;  // นับถอยหลัง 5 วินาที
var count=0;
var lvl=0;
function  countdown(){
		var current=new Date();
		var diff =current-offset;
		var min="00",sec="00";
		
		if(diff >startTime){
			count++;
			if(count>10){
				lvl++;
				count=1;
				document.getElementById('lvl').innerHTML =lvl;
			}
			offset =new Date();
			current.setTime(startTime);
			min=(current.getMinutes().toString().length==1)?"0"+current.getMinutes():current.getMinutes();
			sec =(current.getSeconds().toString().length==1)?"0"+current.getSeconds():current.getSeconds();
			document.getElementById('health').src="drawImg.php?num="+count;


		}else{
			current.setTime(startTime-diff);
			min=(current.getMinutes().toString().length==1)?"0"+current.getMinutes():current.getMinutes();
			sec =(current.getSeconds().toString().length==1)?"0"+current.getSeconds():current.getSeconds();			
		}
		document.getElementById('countdown').innerHTML=min+"."+sec;
		setTimeout('countdown()',900)
}
window.onload=countdown;
</script>
<div id="countdown"></div>
LVL:<span id="lvl">0</span><br/>
<img src="drawImg.php" id="health">

<?php
Header("Content-type:image/gif");
$img=ImageCreate(100,15);
$white=ImageColorAllocate($img,255,255,255);
$x =ImageColorAllocate($img,145,145,145);
ImageRectangle($img,0,1,99,14,$x);
$num =$_GET[num];
$f=ImageColorAllocate($img,44,246,125);
ImageFilledRectangle($img,0,2,10*$num-1,13,$f);

$font = "c:\\Windows\\fonts\\tahoma.ttf";
$black=ImageColorAllocate($img,0,0,0);
imageTTFText($img,8,0,70,11,$black,$font,($num*10)."%");

ImageGIF($img);
Imagedestroy($Img);
?>