js下载文件防止白屏

              var ifup = document.getElementById("xman-activity-export-downLoad-file");
              if(ifup) {
                document.body.removeChild(ifup);
              }
              var elemIF = document.createElement("iframe");
              elemIF.id=‘xman-activity-export-downLoad-file‘;
              elemIF.src = ret?.data?.value?.exportOSSKey;
              elemIF.style.display = "none";
              document.body.appendChild(elemIF);