function
fs.promises.appendFile
data: string | ArrayBufferView<ArrayBufferLike> | Iterable<unknown, any, any> | AsyncIterable<unknown, any, any>,
): Promise<void>;
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()).
@param path
filename or {FileHandle}
@returns
Fulfills with undefined upon success.