jquery判断checkbox

<script language="javascript" type="text/javascript">

    function SelectAllCheckboxes() {
        var count = 0;
        $('#<%=GridView1.ClientID %>').find("input:checkbox").each(function() {
            if (this.checked == true) {
                count++;
            }
        });
        if (count == 0) {
            alert('你没有选择任何项');
            return false;
        }
        else {
            return confirm('你确定删除这些项吗?');
        }
    }
</script>

 

 

<asp:Button ID="Button1" runat="server" Text="多项删除" CssClass="btnBg" OnClick="Button_Delete_Click" OnClientClick="return SelectAllCheckboxes();" />