How to append to a file in Node?

Question

I am trying to append a string to a log file. However writeFile will erase the content each time before writing the string.

fs.writeFile(\'log.txt\'         


        

Answer 1

Using fs.appendFile or fsPromises.appendFile are the fastest and the most robust options when you need to append something to a file.

In contrast to some of the answers suggested, if the file path is supplied to the appendFile function, It actually closes by itself. Only when you pass in a filehandle that you get by something like fs.open() you have to take care of closing it.

I tried it with over 50,000 lines in a file.

Examples :

(async () => {
  // using appendFile.
  const fsp = require('fs').promises;
  await fsp.appendFile(
    '/path/to/file', '\r\nHello world.'
  );

  // using apickfs; handles error and edge cases better.
  const apickFileStorage = require('apickfs');
  await apickFileStorage.writeLines(
    '/path/to/directory/', 'filename', 'Hello world.'
  );
})();

Ref: https://github.com/nodejs/node/issues/7560
Example Execution: https://github.com/apickjs/apickFS/blob/master/writeLines.js