js实现DataGrid+CheckBox全选功能

<script language="jscript" type="text/javascript">
    function SelectAll(obj)
{
var flag=obj.checked;
var GridViewCtl=document.getElementById('gvStudy');
var count=GridViewCtl.rows.length;

for(var i=1;i<count;i++)
{
//gvshow.rows[i].cells[0].firstChild.checked=flag;
GridViewCtl.rows[i].getElementsByTagName("input")[0].checked = flag;

}
}

    </script>

DataGird：

<asp:TemplateField HeaderText="选择">
                                            <HeaderTemplate>
                                                <asp:CheckBox ID="chkAll" onclick="SelectAll(this);" runat="server" />选择
                                            </HeaderTemplate>
                                            <ItemTemplate>
                                                <asp:CheckBox ID="chkSelect" runat="server" />
                                            </ItemTemplate>
                                            <HeaderStyle HorizontalAlign="Left" />
                                        </asp:TemplateField>