<script type="text/javascript">

        $(function () {

            $("#ddlNumber").change(function () {

                var number = $("#ddlNumber").find("option:selected").val();

                if (number != "") {

                    $("#allCheck").attr("checked", false);

                    $("[name = $chkItem]:checkbox").attr("checked", false);

                    for (var i = 0; i < number; i++) {

                        $("[name = $chkItem]:checkbox").eq(i+1).attr("checked", true);

                    }

                }

            });

            $("#allCheck").bind("click", function () {

                $("[name = $chkItem]:checkbox").attr("checked", $(this).attr("checked"));

            });

        })

</script>

var tmp = '<input name="companyID" type="checkbox" value="' + row["CompanyID"] + '" onclick="userCheck(this)">'

function userCheck(obj) {

    if (obj.checked) {

        var allCheckbox = $("input[name='companyID']");

        for (var i = 0; i < allCheckbox.length; i++) {

            allCheckbox[i].checked = false;

        }

        obj.checked = true;//设置checkbox的方式之一

    }

}

var inputs2 = $("input[id$=cbxSelect]", document.getElementById("<% =grvScale.ClientID %>"));

var flag = false;

for (var i = 0; i < inputs2.length; i++)

{

    if (inputs2[i].checked == true) //$(allCheckbox[i]).is(':checked')

    {

        flag = true;

    }

}