終于寫出來了
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<html >
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>系好安全帶,準備啟航</title>
<script type="text/javascript">
? //通過javascript的日期對象來得到當前的日期，并輸出。
? var date = new Date();
? var weekday=["星期日","星期一","星期二","星期三","星期四","星期五","星期六"];
? document.write(date.getFullYear()+"年");
? document.write(date.getMonth()+1+"月");
? document.write(date.getDate()+"日");
? document.write(" "+weekday[date.getDay()] +"--");
?
? //成績是一長竄的字符串不好處理，找規律后分割放到數組里更好操作哦
? var scoreStr = "小明:87;小花:81;小紅:97;小天:76;小張:74;小小:94;小西:90;小伍:76;小迪:64;小曼:76";
? var arr=scoreStr.split(";");
?
?
? //從數組中將成績撮出來，然后求和取整，并輸出。
? var sum=0;
? for(var i=0;i<arr.length;i++){
??? sum=sum+parseInt(arr[i].substr(3));
? }
? document.write("班級平均分為："+Math.floor(sum/arr.length));
</script>
</head>
<body>
</body>
</html>
2019-01-25
<!DOCTYPE??HTML><html?><head><meta?http-equiv="Content-Type"?content="text/html;?charset=utf-8"?/><title>系好安全帶,準備啟航</title><script?type="text/javascript">??//通過javascript的日期對象來得到當前的日期，并輸出。??var?mydate?=?new?Date();??var?year?=?mydate.getFullYear()??var?month?=?mydate.getMonth()??switch(month){????case?0:?????????month?=?'01';????????break;????case?1:?????????month?=?'02';????????break;????case?2:?????????month?=?'03';????????break;????case?3:?????????month?=?'04';????????break;????default:????????month?=?'獲取的月份不存在';??};??var?day?=?mydate.getDate();??var?hourse?=?mydate.getHours();??var?minutes?=?mydate.getMinutes();??var?seconds?=?mydate.getSeconds();??document.write(year+'年'+month+'月'+day+'日'+hourse+'點'+minutes+'分'+seconds+'秒'+'<br/>')????//成績是一長竄的字符串不好處理，找規律后分割放到數組里更好操作哦??var?scoreStr?=?"小明:87;小花:81;小紅:97;小天:76;小張:74;小小:94;小西:90;小伍:76;小迪:64;小曼:76";??var?myarr?=?scoreStr.split(';');??document.write(myarr+'<br/>');??var?sum?=?0;??for(var?i?=?0;?i<myarr.length;?i++){??????var?str?=?myarr[i].toString()??????sum?+=?parseInt(str.substring(3));??}??var?verage?=?parseInt(sum?/?myarr.length)??document.write(verage)??????//從數組中將成績撮出來，然后求和取整，并輸出。??</script></head><body></body></html>