nodejs prepending to a file

Question

For Node.js, what is the best way to prepend to a file in a way SIMILAR to

fs.appendFile(path.join(__dirname, 'app.log'), 'appendme', 'utf8')

Personally, the best way really revolves around a asynchronous solution to create a log where I can basically push onto the file from the top.

Answer 1

This solution isn't mine and I don't know where it's from but it works.

const data = fs.readFileSync('message.txt')
const fd = fs.openSync('message.txt', 'w+')
const insert = Buffer.from("text to prepend \n")
fs.writeSync(fd, insert, 0, insert.length, 0)
fs.writeSync(fd, data, 0, data.length, insert.length)
fs.close(fd, (err) => {
  if (err) throw err;
});

Answer 2

It is impossible to add to a beginning of a file. See this question for the similar problem in C or this question for the similar problem in C#.

I suggest you do your logging in the conventional way (that is, log to the end of file).

Otherwise, there is no way around reading the file, adding the text to the start and writing it back to the file which can get really costly really fast.

Answer 3

It seems it is indeed possible with https://www.npmjs.com/package/prepend-file