文件下载重命名时扩展名被误识别怎么办？

export const downloadFile = (fileUrl, fileName, errorCallback) => {
    try {
        const xhr = new XMLHttpRequest();
        xhr.open("GET", fileUrl, true);
        xhr.responseType = "blob";
        xhr.send();
        xhr.onload = function () {
            if (this.status === 200 || this.status === 304) {
                const contentType = xhr.getResponseHeader("Content-Type");
                let extension = "";
                if (contentType) {
                    // 根据Content-Type确定扩展名，可根据实际情况扩展
                    if (contentType.includes("pdf")) {
                        extension = ".pdf";
                    } else if (contentType.includes("zip")) {
                        extension = ".zip";
                    } else if (contentType.includes("txt")) {
                        extension = ".txt";
                    } // ... 添加其他类型判断
                }

                const blob = new Blob([this.response], { type: contentType });
                const finalFileName = fileName + extension; // 追加扩展名
                if ("msSaveOrOpenBlob" in navigator) {
                    navigator.msSaveOrOpenBlob(blob, finalFileName);
                    return;
                }
                const url = URL.createObjectURL(blob);
                simulateClick(blob, finalFileName, "_blank");
                URL.revokeObjectURL(url);
            }
        };
        xhr.onerror = function () {
            errorCallback && errorCallback();
        };
    } catch (error) {
        errorCallback && errorCallback();
    }
};