这样的复选框如何实现全选功能？

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>用户列表</title>
<link href="images/admin.css" rel="stylesheet" type="text/css">
<script language="JavaScript">
<!--
function editUserFun(form)
{
if(form.pass_word.value.length!=0 && form.pass_word.value!=form.confirm.value)
{
alert("您输入的两次密码不相同，请确认！");
form.pass_word.focus();
return false;
}
else if(form.pass_word.value.length>0)
{
return confirm("您确定要修改该用户密码？");
}
else
{
return true;
}
}
function CheckAll(form) {
for (var i=0;i<form.elements.length;i++) {
var e = form.elements[i];
if (e.name != 'chkall' && e.type=='checkbox')
e.checked = form.chkall.checked;
}
}
// -->
</script>
</head><body>
<table width="90%" border="0" align="center" cellpadding="5" cellspacing="1" bgcolor="#CCCCCC">
  <tr bgcolor="#FFFFFF">
    <td colspan="5" bgcolor="#C7ECFC" class="optTitle"> 用户列表</td>
  </tr>
<FORM METHOD=GET ACTION="">
    <tr bgcolor="#FFFFFF">
    <td colspan="5" bgcolor="#FFFFFF" align=right>
<INPUT TYPE="hidden" name="CH" value="userList">
<SELECT NAME="user_group">
   <option value="">　全　部　</option>
   <option value="Parents">　家　长　</option>
   <option value="Teacher">　导　师　</option>
   <option value="Janitor">管　理　员</option>
   <option value="Administrator">超级管理员</option>
</SELECT>
<SELECT NAME="user_stat">
   <option value="">全部</option>
   <option value="Y">正常</option>
   <option value="N">停用</option>
</SELECT>
<SELECT NAME="belong_class">
   <option value="">　不　限　制　</option>
   
<option value='6'>[2003] 小一班</option><option value='4'>[2003] 中一班</option><option value='11'>[2002] 中一班</option><option value='9'>[2002] 小一班</option>
</SELECT>
    <INPUT TYPE="text" NAME="user_name" class="input_submit" size=10>&nbsp;&nbsp;<INPUT TYPE="submit" name="orderList" value="列表" class="input_submit">
</td>
  </tr>
  </FORM>
<FORM METHOD=POST ACTION="">
    <tr bgcolor="#FFFFFF">
    <td width=6% align=center>序</td>
<td width=8% align=center>状态</td>
<td align=center>用户名称</td>
<td width=20% align=center>注册日期</td>
<td width=18% align=center><INPUT TYPE="submit" name="removeAll" value="删除" class="input_submit" onClick="return confirm('确信删除所选用户？');">&nbsp;&nbsp;<input type="checkbox" name="chkall" value="on" onclick="CheckAll(this.form)" title="点击可全选"></td>
  </tr>                      <tr bgcolor='#FFFFFF' class='lockFont'>
                          <td width='6%' align=center>1</td>
                      <td width='9%' align=center><B>停用</B></td>
                      <td align=center>aaaaaa</td>
                      <td width='20%' align=center>2004-03-11</td>
                      <td width='18%' align=center><INPUT TYPE='submit' name='editUserId[9]' value='编辑' class='input_submit'>&nbsp;&nbsp;<INPUT TYPE='checkbox' NAME='remove[9]'></td>
                     </tr>

                      <tr bgcolor='#FFFFFF' >
                          <td width='6%' align=center>2</td>
                      <td width='9%' align=center>正常</td>
                      <td align=center>管理员</td>
                      <td width='20%' align=center>2004-02-28</td>
                      <td width='18%' align=center><INPUT TYPE='submit' name='editUserId[3]' value='编辑' class='input_submit'>&nbsp;&nbsp;<INPUT TYPE='checkbox' NAME='remove[3]'></td>
                     </tr>

                      <tr bgcolor='#FFFFFF' >
                          <td width='6%' align=center>3</td>
                      <td width='9%' align=center>正常</td>
                      <td align=center>gzccie</td>
                      <td width='20%' align=center>2004-02-28</td>
                      <td width='18%' align=center><INPUT TYPE='submit' name='editUserId[2]' value='编辑' class='input_submit'>&nbsp;&nbsp;<INPUT TYPE='checkbox' NAME='remove[2]'></td>
                     </tr>

                      <tr bgcolor='#FFFFFF' >
                          <td width='6%' align=center>4</td>
                      <td width='9%' align=center>正常</td>
                      <td align=center>网络混混</td>
                      <td width='20%' align=center>2004-02-28</td>
                      <td width='18%' align=center><INPUT TYPE='submit' name='editUserId[1]' value='编辑' class='input_submit'>&nbsp;&nbsp;<INPUT TYPE='checkbox' NAME='remove[1]'></td>
                     </tr>
<tr bgcolor=#FFFFFF><td colspan=5 bgcolor=#FFFFFF align=right><a href="/test/admincenter.php?CH=userList&page=1" title="首页">首页</a> <a href='/test/admincenter.php?CH=userList&page=1' title="上一组">[<<]</a><a href='/test/admincenter.php?CH=userList&page=1'><font color='#ff0000'>[1]</font></a><a href='/test/admincenter.php?CH=userList&page=1' title="下一组">[>>]</a> <a href="/test/admincenter.php?CH=userList&page=1" title="尾页">尾页</a></td></tr></FORM>
</table>
</body>
</html><div class='runTime' align='CENTER'>Script Execution Time : 0.0145 Second&nbsp;&nbsp;Querys:5</div><BR><BR><BR>