KSUID implemented in Google Apps Script

KSUID.gs

// Pseudorandom number generator function
function getRandomBytes(length) {
  var result = [];
  for (var i = 0; i < length; i++) {
    result.push(Math.floor(Math.random() * 256));
  }
  return result;
}

// Convert bytes to base62 string
function bytesToBase62(bytes) {
  var base62Chars = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
  var result = '';
  var num = 0;

  for (var i = 0; i < bytes.length; i++) {
    num = num * 256 + bytes[i];
  }

  while (num > 0) {
    result = base62Chars.charAt(num % 62) + result;
    num = Math.floor(num / 62);
  }

  return result;
}

// KSUID generation function
function generateKSUID() {
  // Generate timestamp
  var timestamp = Math.floor((new Date().getTime() / 1000) - 1400000000); // Adjust epoch to May 13th, 2014

  // Generate random payload (128 bits)
  var payload = getRandomBytes(16);

  // Concatenate timestamp and payload
  var bytes = [];
  bytes.push(timestamp >>> 24 & 0xFF);
  bytes.push(timestamp >>> 16 & 0xFF);
  bytes.push(timestamp >>> 8 & 0xFF);
  bytes.push(timestamp & 0xFF);
  bytes.push.apply(bytes, payload);

  // Encode concatenated value using base62
  var base62Str = bytesToBase62(bytes);

  // Pad result to ensure it always has a fixed length of 27 characters
  var result = base62Str.padEnd(27, '0');

  return result;
}