fs write new data to file existing code example

Example 1: How to append to a file in Node?

// Asynchronously:
const fs = require('fs');

fs.appendFile('message.txt', 'data to append', function (err) {
  if (err) throw err;
  console.log('Saved!');
});

// Synchronously:
const fs = require('fs');

fs.appendFileSync('message.txt', 'data to append');

Example 2: writefile in node js

// writefile.js

const fs = require('fs');

let lyrics = 'But still I\'m having memories of high speeds when the cops crashed\n' + 
             'As I laugh, pushin the gas while my Glocks blast\n' + 
             'We was young and we was dumb but we had heart';

// write to a new file named 2pac.txt
fs.writeFile('2pac.txt', lyrics, (err) => {
    // throws an error, you could also catch it here
    if (err) throw err;

    // success case, the file was saved
    console.log('Lyric saved!');
});