10.js

const fs = require('fs');
const appendData = 'This data will be appended to the file.\n';
fs.appendFile('example.txt', appendData, (err) => {
 if (err) {
 console.error(err);
 return;
 }
 console.log('Data appended to file!');
});
const content = 'This data will be written to the file.\n';
fs.open('example2.txt', 'w', (err, fd) => {
 if (err) {
 console.error(err);
 return;
 }
 fs.writeFile(fd, content, (err) => {
 if (err) {
 console.error(err);
 return;
 }
 console.log('File written successfully!');
 fs.close(fd, (err) => {
 if (err) {
 console.error(err);
 }
 console.log('File closed successfully!');
 });
 });
});
const data = 'This data will overwrite the content of the file.\n';
fs.writeFile('example3.txt', data, (err) => {
 if (err) {
 console.error(err);
 return;
 }
 console.log('File written successfully!');
});