Simple XOR error correction demo

xor.js

// Simple XOR error correction demo.
"use strict";

const packets = [
  "hello world",
  "JavaScript!",
  "lose me plz",
  "another one"
].map((s) => new Buffer(s));


// We send all 4 packets...
const sentPackets = packets;
console.log('sent packets:', sentPackets.map(p => p.toString()));

// ...and one error correction packet, which is a XOR of all packets.
const correctionPacket = packets.reduce((p, c) => {
  for (let i = 0; i < p.length; i++) {
    p[i] ^= c[i];
  }
  return p;
}, new Buffer(packets[0].length).fill(0));

console.log('correction packet: ', correctionPacket.toString('hex'));

// Something loses one of our packets...
const lostPacket = packets[Math.floor(Math.random() * packets.length)];

// ...and we receive only 3 packets and the error correction packaet.
const receivedPackets = sentPackets.filter(p => p !== lostPacket);
console.log('received packets:', receivedPackets.map(p => p.toString()));

// We can recover the lost packet by simply XORing all received
// packets with the correction packet.
const recoveredPacket = receivedPackets.reduce((p, c) => {
  for (let i = 0; i < p.length; i++) {
    p[i] ^= c[i];
  }
  return p;
}, new Buffer(correctionPacket));

// viola!
console.log('recovered packet: ', recoveredPacket.toString());