How to append a data to a file in Node.js

In this tutorial, we will learn about two different ways to append data to a file in Node.js.

Using the fs.appendFileSync() method

The fs.appendFileSync() method synchronously append data to a file, it also creates a new file if a file doesn’t exist in your file system.

Data can be either string or Buffer.

Example:

const fs = require('fs');

fs.appendFileSync('songs.txt', 'my first song');

The first argument in the appendFileSync() method is filename and second argument is the data you need to append to that file.

Using the fs.appendFile() method

The fs.appendFile() method asynchronously append data to a file, it also creates a new file if a file doesn’t exist in your file system.

Example:

fs.appendFile('songs.txt', 'my first song', (err) => {
  if (err) throw err;
  console.log('The "my first song" was appended to file!');
});

The first argument in the appendFile() method is filename, the second argument is the data you need to append to that file and third argument is callback function where it runs with an error argument once a data is appended to the file.