const fs = require('fs');

// read
fs.readFile('sample.txt', (error, data) => {
    if (error) {
        console.error(error);
    } else {
        console.log(data);
    }
});

// read sync
try {
    const data = fs.readFileSync('sample.txt');
    console.log(data);
} catch (error) {
    console.error(error);
}

// write
const content = 'Test Text';
fs.writeFile('test.txt', content, (error) => {
    if (error) {
        console.error(error);
    }
});


// write sync, append mode
try {
    fs.writeFileSync('test.txt', content, { flag: 'a+' });
} catch (error) {
    console.error(error);
}

// another append mode
fs.appendFile('test.txt', content, (error) => {
    if (error) {
        console.error(error);
    }
});