頁面上按Enter鍵的事件

如下的一個登陸：

<script>

function KeyP() {

            if (event.keyCode == 13 ){
                document.getElementById('Btn_DengL').click(); 

            }
        }

</script>

<table width="300" align="center" class="tb">
                    <tr>
                    <th scope="col">用戶名：</th>
                       <th scope="col"><input id="userid" type="text" size="20" class="textbox_style" style="height:15px;width:146px" οnkeypress="KeyP()"  /> 
                       <input id="none" type="hidden" value=""/>
                        </th></tr>     
                       <tr><th scope="col">密&nbsp; 碼：  </th>                    
                           <th scope="col"><input id="password" type="password" size="20" style="height:15px;width:146px" class="textbox_style" οnkeypress="KeyP()"  /></th></tr>  
                           <tr>
                                <td></td><td>
                               <img alt="" src="~/images/186X/login.gif" runat="server"  id="Btn_DengL" οnclick="DengLClick()" style="cursor:hand"/>  
                               <img alt="" src="~/images/186X/reg.gif"  runat="server"  id="Btn_Reg"  οnclick="GoReg()" style="cursor:hand"/>
                              </td></tr>
                     </table>

不管焦點在用戶名、密碼還是登陸按鈕上，按Enter時，都會觸發登陸按鈕事件