Node.js append raw bytes to file

Question

I want to append 4 bytes to a raw data file.

This code would write text, but there's no guide to doing raw bytes

fs = require('fs');
fs.writeFile('helloworld.txt', 'Hello World!', function (err) {
  if (err) return console.log(err);
  console.log('Hello World > helloworld.txt');
});

You can use the nodejs [buffer object](https://nodejs.org/api/buffer.html#static-method-bufferfrombuffer) to write a buffer to file. — about14sheep, Feb 03 '22 at 23:59
Would probably use a Buffer to do that. See: https://stackoverflow.com/questions/2496710/writing-files-in-node-js — Felipe Esteves, Feb 03 '22 at 23:59
`fs.appendFile()` will append bytes to the end of an existing file. — jfriend00, Feb 04 '22 at 04:48

score 0 · Answer 1 · answered Feb 04 '22 at 01:20

fs.writeFile() accepts a Buffer as well as a string.

This example would append three 0x01 bytes to a file:

const fs = require('fs');

fs.writeFile('helloworld.txt', Buffer.from([0x01, 0x01, 0x01]), { flag: "a" }, function (err) {
  if (err) return console.log(err);
  console.log('Hello World > helloworld.txt');
});

Node.js append raw bytes to file

1 Answers1