<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>分数等级</title>
</head>html
<body>
<script>
//建立变量B,并将用户输入的成绩赋值给B，再将B/10向下取整从新赋值给B；
var b = prompt("请输入成绩");
while(b<0||b>100){
var b = prompt("成绩不合法，请从新输入成绩");
}
var b =Math.floor(b/10);
//当B结果为6-10时，输出A-D级，其他输出E级；
switch(b){
case 10:
document.write("A级");
break;
case 9:
document.write("A级");
break;
case 8:
document.write("B级");
break;
case 7:
document.write("C级");
break;
case 6:
document.write("D级");
break;
default:
document.write("E级");
break;
}
</script>
</body>
</html>ui