跨域form下载方式 批量下载

downloadFileForm:function(fid) {

var url = "https://file.xxxx.com/fileDownload.do";
var inputs = "<input type=‘hidden‘ name=‘param‘ value=‘‘ />";
var subNode = $(‘<form action="‘ + url + ‘" method="post" enctype="application/octet-stream">‘ + inputs + ‘</form>‘).appendTo(‘body‘);
subNode.find("input").val("{‘type‘= 0, ‘fileId‘="+fid+",‘time‘=" + new Date().getTime() + "}");
subNode.submit();
},

 function down(downfile) {


            var fileExt = (/[.]/.exec(downfile)) ? /[^.]+$/.exec(downfile.toLowerCase()) : ‘‘;
            fileExt = fileExt[0];

            var xhr = new XMLHttpRequest();


            xhr.open(‘GET‘, downfile, true);

            xhr.responseType = ‘blob‘;
            xhr.onload = function (e) {
                if (this.status == 200) {

                    let res = this.response;  //不是responseText。

                    let blob = new Blob([res], {type: mimeType[fileExt]});


                    //  var blob = this.response;
                    console.log(blob);

                    var filename = "爱搜打打";
                    var a = document.createElement(‘a‘);
                    var url = URL.createObjectURL(blob);
                    a.href = url;
                    a.download = filename;
                    a.click();
                    window.URL.revokeObjectURL(url);

                }
            };
            xhr.send();

        }