asp.net updatepanel 导致JS不能加载,而无法使用的解决方法

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

    var prm = Sys.WebForms.PageRequestManager.getInstance();

    prm.add_endRequest(function () {

        // re-bind your jquery events here 

        $(document).ready(function () {

            //begin

            var span = $("input[id*='txtSpan']");

            span.focusout(function () {

                var greaterthenzero = (span.val() == 0);

                if (span.val() == 0) {

                    $("#spRule").show();

                    $("input[id*='btnSave']").attr("disabled","disabled");

                }

                else {

                    $("#spRule").hide();

                    $("input[id*='btnSave']").removeAttr("disabled");

                }

            });

            //end

        });

    }

 );

</script>