使用PHP在IE上发出两次javascript警报 - javascript alert twice issue on IE with PHP

javascript alert twice issue on IE with PHP

IE问题，如果我在除IE之外的所有浏览器中运行此脚本，它会提醒表单提交一次，但如果我尝试IE，它会警告两次，

原因可能是什么？

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<?php
if(isset($_POST['btn_submit']) && $_POST['btn_submit'] == 'Submit')
{
    ?>
        <script language="javascript">  
        alert('form submitted');
        </script>    
    <?php   
}
?>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Untitled Document</title>
</head>
<body>
<form id="name" method="post">
    <input type="file"/>
    <input type="submit" name="btn_submit" value="Submit" />
</form> 
</body>
</html>

编辑：我在IE7和IE8 上尝试了这个代码

在脚本末尾尝试js:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Untitled Document</title>
</head>
<body>
<form id="name" method="post">
    <input type="file"/>
    <input type="submit" name="btn_submit" value="Submit" />
</form> 
</body>
</html>
<?php
if(isset($_POST['btn_submit']) && $_POST['btn_submit'] == 'Submit')
{
    ?>
        <script language="javascript">  
        alert('form submitted');
        </script>    
    <?php   
}
?>

试试这种方法，它有点干净。

  <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
  <html xmlns="http://www.w3.org/1999/xhtml">
  <head>
  <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
  <title>Untitled Document</title>
  <script src="//ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script>
  <script type="text/javascript"> 
  $(document).ready(function() {
    $('#name').submit(function(event){
         event.preventDefault();
         // Do other stuff   
         alert('form submitted');
    });
   });
  </script>
  </head>
  <body>
     <form id="name" method="post">
        <input type="file"/>
        <input type="submit" name="btn_submit" value="Submit" />
     </form> 
  </body>
  </html>