Jquery File download ($.fileDownload)

 function exportToExcelTest() {

        var region = $('#ddlRegion').val();
        var hrinfo = $('#hrinfodropdown').val();
        if (region != null) {
            $('#ExportOptions').modal('hide');
            $.blockUI({ message: '<h1>Please wait generating excel data...</h1>' });
            //$.blockUI({ message: '<h1><img src="../Images/ajax_loader_blue_350.gif" /> Just a moment...</h1>' });
            $.blockUI({ css: { backgroundColor: '#f00', color: '#fff'} });
            var myData = region + ':' + hrinfo;

            $.fileDownload('Excel.ashx', {
                httpMethod: "POST",
                data: { data: myData },
                successCallback: function (url) {
                    //$("div#loading").hide();
                    //alert('ok');
                    //response.setHeader("Set-Cookie", "fileDownload=false; path=/");
                    $.unblockUI();
                },
                prepareCallback: function (url) {
                    //alert('ok');
                    //response.setHeader("Set-Cookie", "fileDownload=true; path=/");
                    $.unblockUI();
                },
                failCallback: function (responseHtml, url) {
                    //alert('ok');
                    // $("div#loading").hide();
                    // alert('Error while generating excel file');
                    //response.setHeader("Set-Cookie", "fileDownload=false; path=/");
                    $.unblockUI();
                }
            });          
        }
        else {
            alert('Please select a region....');
            return false;
        }
    }

https://stackoverflow.com/questions/13853300/jquery-file-download-filedownload

https://blog.csdn.net/weixin_41029960/article/details/82585082?utm_medium=distribute.pc_relevant.none-task-blog-baidujs_title-1&spm=1001.2101.3001.4242

https://stackoverflow.com/questions/52495935/how-to-download-a-file-from-java-controller-to-javascript