新手求问，关于js登录验证有关问题

新手求问，关于js登录验证问题

PHP code

<!--

Code highlighting produced by Actipro CodeHighlighter (freeware)
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--><script type="text/javascript">
    function logincheck(){
        if (loginform.user.value=""){
            alert ("请输入用户名");
            loginform.user.focus();
            return false;    
        }
        if (loginform.pw.value=""){
            alert ("请输入用户名");
            loginform.pw.focus();
            return false;    
        }
    }
</script>



    <div id="login">
    
         <div id="top">
           <div id="top_left"><img  src="images/login_03.gif" alt=" 新手求问，关于js登录验证有关问题 " ></div>
              <div id="top_center"></div>
         </div>
         <form action="login.php" method="post" name="loginform" onsubmit="return logincheck(this);">
             <div id="center">
                  <div id="center_left"></div>
                  <div id="center_middle">
                       <div id="user">用 户
                         <input type="text" name="user">
                       </div>
                       <div id="password">密   码
                         <input type="password" name="pw">
                       </div>
                       <div id="btn">
                        <input type="submit" value="登录" name="submit">
                        <input type="reset" value="取消" name="reset">
                       </div>
                  
                  </div>
                  <div id="center_right"></div>         
             </div>
         </form>
         <div id="down">
              <div id="down_left">
                  <div id="inf">
                       <span class="inf_text">版本信息</span>
                       <span class="copyright">留言管理系统 2012 v1.0</span>
                  </div>
              </div>
              <div id="down_center"></div>         
         </div>

    </div>

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