Untitled

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title></title>
    </head>
    <body bgcolor="#666" style="color:#FFF">
        <form name="RegisterForm" action="changepw.php" method="POST">
            <input type="hidden" name="Method" value="create"/>
            <table>
                 <tr>
                     <td colspan="2"><h1>Change Password</h1></td>
                 </tr>
                        <tr>
                    <td>
                        UserID：
                    </td>
                    <td>
            <input type="text" name="user" value=""/>
            </td>
            </tr>
            <tr>
                <td>
                   Current Password：
                </td>
                <td>
            <input type="password" name="opass" value=""/>
            </td>
            </tr>
            <tr>
                <td>
                    New Password：
                </td>
                <td>
            <input type="password" name="npass" value=""/>
            </td>
            </tr>
             <tr>
                <td>
                    New Password (confirm)：
                </td>
                <td>
            <input type="password" name="npass2" value=""/>
            </td>
            </tr>
            <tr>
                <td>
                    <input type="button" onclick="OnSubmit();" value="Change">
            </td>
            </tr>
            </table>
        </form>
    </body>
    <script>
        function OnSubmit()
        {
        	var user=document.getElementsByName("user")[0].value;
            var opass=document.getElementsByName("opass")[0].value;
            var npass=document.getElementsByName("npass")[0].value;
            var npass2=document.getElementsByName("npass2")[0].value;
            if(user==""||opass==""||npass==""||npass2=="")
            {
                alert('Some fields are empty!!');
                return;
            }
            if(npass!=npass2)
            {
                alert('Passwords do not match!!');
                document.getElementsByName("npass")[0].value="";
                document.getElementsByName("npass2")[0].value="";
                return;
            }
            if(!user.match(/^[A-Za-z0-9]+$/))
            {
                alert('Invalid UserID.');
                document.getElementsByName("user")[0].value="";
                return;
            }
            if(!npass.match(/^[A-Za-z0-9]+$/))
            {
                alert('Invalid New Password');
                document.getElementsByName("npass")[0].value="";
                document.getElementsByName("npass2")[0].value="";
                return;
            }

            var frm=document.getElementsByName("RegisterForm")[0];
            frm.submit();
        }
    </script>
</html>