vue 兼容ie 下载文件

 handlePreview(file) {
      getFile(file.id)
        .then(res => {
          const blob = new Blob([res]);
          if (window.navigator.msSaveOrOpenBlob) {
            // 兼容IE
            navigator.msSaveBlob(blob, file.name);
          } else {
            var a = document.createElement("a");
            var event = new MouseEvent("click");
            a.download = file.name;
            a.href = window.URL.createObjectURL(blob);

            a.dispatchEvent(event);
          }
        })
        .catch(err => {
          console.log("err", err);
        });
    }