fsPromises.appendFile(path, data[, options])


    异步地将数据追加到文件,如果该文件尚不存在,则创建该文件。 data 可以是字符串或 <Buffer>

    Asynchronously append data to a file, creating the file if it does not yet exist. data can be a string or a <Buffer>.

    If options is a string, then it specifies the encoding.

    The mode option only affects the newly created file. See fs.open() for more details.

    The path may be specified as a <FileHandle> that has been opened for appending (using fsPromises.open()).