模块设计：
1.域、域标题标记
<fieldset>
<legend align="center">计算1!+2!+...+N！</legend>
<script type="text/javascript">
var n=prompt("输入整数N",0);//输入整数N
//判断N是否有效
var result=1;sum=0;
for (var i=1;i<=n;i++) {
result=result*i;
document.write("<br>"+i+"!="+result);
sum=sum+result;
}
document.write("<br>阶乘的和="+sum);
</script>
</fieldset>
2.样式style标记设计
<style type="text/css">
fieldset{margin:20px auto;
width:300px;
padding:20px auto;
border:2px outset #009966;}
legend{font-size:28px;font-weight:bolder;}
</style>
3.for循环部分
for (var i=1;i<=n;i++) {
result=result*i;
document.write("<br>"+i+"!="+result);
sum=sum+result;
}
完整程序实现：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title> 计算1!+2!+...+N! </title>
<style type="text/css">
fieldset{margin:20px auto;
width:300px;padding:20px auto;
border:2px outset #009966;}
legend{font-size:28px;font-weight:bolder;}
</style>
</head>
<body>
<fieldset>
<legend align="center">计算1!+2!+...+N！</legend>
<script type="text/javascript">
var n=prompt("输入整数N",0);//输入整数N
//判断N是否有效
var result=1,sum=0;
for (var i=1;i<=n;i++) {
result=result*i;
document.write("<br>"+i+"!="+result);
sum=sum+result;
}
document.write("<br>阶乘的和="+sum);
</script>
</fieldset>
</body>
</html>
实现效果：
