JS中的form.submit()不能提交表单的错误原因

<div id="register">
     <h4>会员注册</h4>
     <div class="formdiv">
         <form method="post" action="register.php?action=register" name="register" id="registerForm">
             <dl>
                 <dt>请认真填写以下内容</dt>
                 <dd class="hasspan">
                     用户名：<input type="text" name="username">
                 </dd>
                 <dd class="hasspan">
                     密码：<input type="password" name="pwd">
                 </dd>
                 <dd class="hasspan">
                     确认密码：<input type="password" name="pwdagain">
                 </dd>
                 <dd id="tximg">
                     <img src="img/face/m01.gif" style="border-left-color: rgb(0, 153, 204); border-left-width: 1px; border-left-style: solid; padding: 0px 3px; margin: 3px auto 0px; width: 640px; background-color: rgb(242, 246, 251); clear: both; font-size: 14px; border-top-color: rgb(0, 153, 204); border-top-width: 1px; border-top-style: solid; border-right-color: rgb(0, 153, 204); border-right-width: 1px; border-right-style: solid; line-height: 25px; color: rgb(0, 0, 0); font-family: Tahoma, Helvetica, Arial, 宋体, sans-serif;"> 复制代码代码如下:

 /*注册表单提交*/
 function formDeal()
 {
     var btnSubmit = document.getElementById('submit');
     var formId = document.getElementById('registerForm');
     btnSubmit.onclick = function()
     {
         //表单的submit()方法不能提交表单
         formId.submit();
     }

 

 }

 if(!empty($_GET['action']) && $_GET['action'] == 'register')
 {
     echo '你提交了数据';
     exit();
 }

 this.type="submit"