<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>验证码测试登录页面</title>
<script type="text/javascript">
function changeimg() {
var myimg = document.getElementById("code");
now = new Date();
myimg.src = "yzm.php?code=" + now.getTime();
}
</script>
</head>
<body>
<center>
<form action="yzm.php" method="post" />用户名：
<input type="text" name="username" />
<br>密 码：
<input type="password" name="password" />
<br> 验证码：
<input type="text" name="certCode" />
<img id="code" src="yzm.php"><a href="javascript:changeimg()">看不清，换一张 </a>
<br>
<input type="submit" value="登录" />
</form>
</center>
</body>
</html>
追问请用jquery的方式来写这种已经会了