下面是我在课本上的一到习题！根据学生的等级评A B C D级。
<script language="javascript">
document.write("<font size='+1'>");
while(true){
var score=eval(prompt("Please input the score:",""));
if (score<0 || score>100){
document.writeln("The score should be between 0 to 100!");
continue;
}
if(score>89 && score<101){
document.writeln("The degree is: A");
}
else if (score>79 && score<90){
document.writeln("The degree is: B");
}
else if(score>69 && score<80){
document.writeln("The degree is: c");
}
else if(score>59 && score<70);{
document.writeln("The degree is: D");
}
else {
document.writeln("It is bad!");
}
answer = prompt("Do you want to input another student?","");
if(answer !="y"){
break;
}
}
document.write("终于可以休息了．．．<br>");
</script>

我仔细的检查过上面的代码好几次了，都没发现什么错误啊！但是浏览的时候就是空白页，什么提示框都没有，真奇怪，请指教吧！呵呵

呵呵,我看过浏览器的左下角,是没有显示网页有错误的.知识显示"完毕".
上面的代码是多了个";"的问题.
经过高人指点我帮上面的代码改了一下,但是看不到效果,请指教吧!呵呵
<script language="javascript">
var score=eval(prompt("Please input the score:",""))
switch(score){
case score>89 && score<101:
document.writeln("The degree is: A");
break;
case score>79 && score<90:
document.writeln("The degree is: B");
break;
case score>69 && score<80:
document.writeln("The degree is: C");
break;
case score>59 && score<70:
document.writeln("The degree is: D");
break;
case score<59:
document.writeln("The degree is: Bad");
break;
}
answer = prompt("Do you want to input another student?","");
if(answer !="y"){
break;
}

</script>