为啥我的代码实现不了啊
<!DOCTYPE HTML>
<html >
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>系好安全带,准备启航</title>
<script type="text/javascript">
var d=new Date();
var year=d.getFullYear();
var month=d.getMonth();
var day=d.getDay();
var weekday=["星期日","星期一","星期二","星期三","星期四","星期五","星期六"];
var mynum=d.getDay();
document.write(year+"年"+month+"月"+day+"日"+weekday[mynum]+"</br>")
//通过javascript的日期对象来得到当前的日期，并输出。
//成绩是一长窜的字符串不好处理，找规律后分割放到数组里更好操作哦
var scoreStr = "小明:87;小花:81;小红:97;小天:76;小张:74;小小:94;小西:90;小伍:76;小迪:64;小曼:76";
var aa=scoreStr.split(";")
var sum=0;
var avg=0;
for{
var i=1;i<=aa.length,i++;
sum = sum + parseInt(aa[i].slice(3,5));}
avg = sum / aa.length;
document.write(parseInt(avg));
</script>
</head>
<body>
</body>
</html>
