求大神指教为什么显示出来的都是零
<DOCTYPE HTML>
<html>
<head>
<meta charset="utf-8"/>
<title></title>
<script>
function toDou(n)
{
if(n<10)
{return '0'+n;}
else{return ''+n;}
}
window.onload=function ()
{
var aImg=document.getElementsByTagName('img')
function tick()
{
var oDate=new Date()
var str=toDou(oDate.getHours())+toDou(oDate.getMinutes())+toDou(oDate.getSeconds())
for(var i=0;i<aImg.length;i++)
{
aImg.src='images/'+str.charAt(i)+'.png';
}
}
setInterval(tick,1000)
tick();
}
</script>
</head>
<body style="background:black; color:white; font-size:59px;"/>
<img src="images/0.png" />
<img src="images/0.png" />
:
<img src="images/0.png" />
<img src="images/0.png" />
:
<img src="images/0.png" />
<img src="images/0.png" />
</body>
</html>
