随机产生验证码
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>随机产生验证码</title>
<style type="text/css">
#code{
width: 145px;
height: 50px;
background-color: lightblue;
font-size: 44px;
letter-spacing: 5px;
text-align: center;
}
#container{
width: 145px;
height: 80px;
background-color: lightblue;
text-align: center;
}
</style>
</head>
<body>
<script type="text/javascript">
function createCode(){
var chars=['Q','D','L','1','2','3'];
var randCode="";
for(var i=0;i<4;i++)//产生4位的随机码
{
var pos=parseInt(Math.random()*(chars.length -1));
randCode+=chars[pos];
}
document.getElementById("code").innerHTML=randCode;
}
</script>
<div id="container">
<div id="code"></div>
<button onclick="createCode()">验证码</button>
</div>
</body>
</html>
猜数字
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>循环结构</title>
</head>
<body>
<script type="text/javascript">
var num,ans;
ans=parseInt(Math.random()*100);
do{
num=prompt("请输入代猜数字.");
if(num==ans)
{
alert("correct answer！");
}
else if(num>ans)
{
alert("bigger than answer！");
}
else alert("smaller than answer！");
}
while(ans!=num);
</script>
</body>
</html>
