缺少对象 问题
<html><head>
</head>
<body >
</body>
<script type="text/javascript">
var i=0;
function a(){
var str="Welcome to my Webdite!!"
var qian=str.substr(0,i);
var hou=str.substr(i,str.length);
var qian1="<font size='30' color='red'>"+qian+"</font>";
var hou1=hou;
document.write(qian1+hou1);
i++;
if(i>str.length){
i=0;
}
window.setTimeout('a()',200) //为什么没有对象
}
window.onload=a;
</script>
</html>