stringify.js

import validate from './validate.js';
/**
 * Convert array of 16 byte values to UUID string format of the form:
 * XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX
 */

const byteToHex = [];

for (let i = 0; i < 256; ++i) {
  byteToHex.push((i + 0x100).toString(16).slice(1));
}

export function unsafeStringify(arr, offset = 0) {
  // Note: Be careful editing this code!  It's been tuned for performance
  // and works in ways you may not expect. See https://github.com/uuidjs/uuid/pull/434
  return (byteToHex[arr[offset + 0]] + byteToHex[arr[offset + 1]] + byteToHex[arr[offset + 2]] + byteToHex[arr[offset + 3]] + '-' + byteToHex[arr[offset + 4]] + byteToHex[arr[offset + 5]] + '-' + byteToHex[arr[offset + 6]] + byteToHex[arr[offset + 7]] + '-' + byteToHex[arr[offset + 8]] + byteToHex[arr[offset + 9]] + '-' + byteToHex[arr[offset + 10]] + byteToHex[arr[offset + 11]] + byteToHex[arr[offset + 12]] + byteToHex[arr[offset + 13]] + byteToHex[arr[offset + 14]] + byteToHex[arr[offset + 15]]).toLowerCase();
}

function stringify(arr, offset = 0) {
  const uuid = unsafeStringify(arr, offset); // Consistency check for valid UUID.  If this throws, it's likely due to one
  // of the following:
  // - One or more input array values don't map to a hex octet (leading to
  // "undefined" in the uuid)
  // - Invalid input values for the RFC `version` or `variant` fields

  if (!validate(uuid)) {
    throw TypeError('Stringified UUID is invalid');
  }

  return uuid;
}

export default stringify;