fs.append 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: node js write file

// fs_write.js

const fs = require('fs');

// specify the path to the file, and create a buffer with characters we want to write
let path = 'ghetto_gospel.txt';
let buffer = new Buffer('Those who wish to follow me\nI welcome with my hands\nAnd the red sun sinks at last');

// open the file in writing mode, adding a callback function where we do the actual writing
fs.open(path, 'w', function(err, fd) {
    if (err) {
        throw 'could not open file: ' + err;
    }

    // write the contents of the buffer, from position 0 to the end, to the file descriptor returned in opening our file
    fs.write(fd, buffer, 0, buffer.length, null, function(err) {
        if (err) throw 'error writing file: ' + err;
        fs.close(fd, function() {
            console.log('wrote the file successfully');
        });
    });
});

Example 3: fs writefile node

const fs = require('fs')

const content = 'Some content!'

fs.writeFile('/Users/joe/test.txt', content, err => {
  if (err) {
    console.error(err)
    return
  }
  //file written successfully
})

Example 4: fs.readfile

fs.readFile('filename', function read(err, data) {
    if (err) {
        throw err;
    }
    var content = data;
  
    console.log(content);  
   
});

Example 5: fs readfile encoding

fs.readFile('/etc/passwd', 'utf8', callback);