NodeJS 和 AngularJS 生成的损坏文件

问：

我在下载文件时遇到问题，我的数据来自 API （NodeJS + Express）。 xlsx 文件只是损坏了，无法打开，就像 zip 格式的文件一样。 一些 xlsx 有奇怪的字符，例如：

Ӫ E Q^ 3 3 ϾhwR- vY！c O y I 㱣 eG [J Gʌw ES lz e L 'Sr 'x2 R Į ¦

这是我的 NodeJS 代码（将数据返回到前面的方法）：

public async downloadFile(patch: string, start: [number, number], timeout: number) {
        try {
            ...

            const buffer: any = [];
            let readStream;
            const downloadPromise = new Promise((resolve, _reject, onCancel) => {
                onCancel(() => {
                    if (readStream) readStream.destroy();
                    return;
                });
                // create the read stream and register events callbacks
                readStream = this.bucket.file(storageInfo.$path).createReadStream();
                readStream.on('error', err => {
                    readStream.destroy();
                    resolve({ downloaded: false, data: err });
                });
                readStream.on('data', data => {
                    buffer.push(data);
                });
                readStream.on('end', () => {
                    readStream.destroy();
                    resolve({ downloaded: true, data: Buffer.concat(buffer) });
                });
            });

            return Response.success({ file: storageInfo, buffer: result.data });

        } catch (ex) {
            ...
        }
    }

Angularjs 代码：

public async previewFileFromGoogleStorage(hash: string): Promise<IFileDownload> {
    try {
        if (!hash) return null;

        const operation = await this.$http({
            method: 'GET',
            url: `${this.getUrlDownload()}${hash}`,
            cache: false,
            timeout: this.timeout,
            responseType: "arraybuffer"
        });
        
        const response: angular.IHttpResponse<any> = operation;
        const parsedReponse = JSON.parse(new TextDecoder().decode(response.data));
        const resultFile = <IDownloadParamsReturn>parsedReponse.data;

        const file = resultFile.file;
        const buffer = resultFile.buffer.data;

        const fileName = file.fileName;
        const fileBuffer = new Uint8Array(buffer);
        const fileType = this.getContentType(file.fileType);
        const fileBlob = new Blob([fileBuffer], { type: fileType });
        const fileURL = window.URL.createObjectURL(fileBlob);
        const result = <IFileDownload> { url: fileURL, name: fileName, type: fileType, blob: fileBlob };

        return result;

    } catch (ex) {
        HandleError.exception(ex);
    }
}

private async sendToDownload(): Promise<void> {
    try {
        this.$scope.file = <IFileDownload>await this.downloadService.previewFileFromGoogleStorage(hash);

        if (this.$scope.file.type.indexOf('image') === 0) {
            this.$scope.type = 'image';
            this.previewImage();
        } else if (this.$scope.file.type === 'application/pdf') {
            this.$scope.type = 'pdf';
            this.previewPdf();
        } else {
            this.$scope.type = 'other';
            const self = this;

            this.$scope.$apply(function () {
                self.blockUI.stop();
                self.downloadFile();
            });
        }
    } catch (ex) {
        this.blockUI.stop();
        HandleError.exception(ex);
    }
}

private downloadFile(): void {
    if (this.$rootScope.isIE) {
        window.navigator.msSaveOrOpenBlob(this.$scope.file.blob, this.$scope.file.name);
    } else {
        let link = document.createElement('a');
        link.href = window.URL.createObjectURL(new Blob([this.$scope.file.blob], { type: this.$scope.file.blob.type }));
        link.download = this.$scope.file.name;
        link.click();
    }
}

我被这个问题困住了，我不知道该怎么办，我已经尝试过将内容类型更改为“blob”或干脆不使用它，但没有奏效。