asp精简checkbox全选代码

<script language="javascript">
function checkall(form)
  {
  for (var i=0;i<form.elements.length;i++)
    {
    var e = form.elements[i];
    if (e.name != "chkall"&&e.disabled==false)
       e.checked = form.chkall.checked;
    }
}
</script>
<form method="post" action="" name="myform">
<input type='checkbox' name="id1" id="id" value='1'><br />
<input type='checkbox' name="id2" id="id" value='1'><br />
<input type='checkbox' name="id2" id="id" value='1'><br />
<input name="chkall" type="checkbox" id="chkall" onclick="checkall(myform)" value="checkbox"> 全部选中
</form>