使用iframe实现无刷新提交表单

<?php  
header("Content-type: text/html; charset=utf8");  
?>  
<iframe name="testIframeName" style="display:none;"></iframe>  
<form target="testIframeName" method="post" action="formAction.php">  
<input type="text" name="username"/>  
<input type="password" name="password"/>  
<input type="submit" value=" 提 交 " />  

</form>

<?php  
$user=$_POST['username'];
$pass=$_POST['password'];
if($user=='an'&&$pass=='123')
echo "<script>alert(登录成功....');</script>";  
?>