UUID pack/unpack

uuid-pack.ts

export function packUUID(uuid: string): string {
    let v;
    let bytes = '';

    // Parse ########-....-....-....-............
    bytes += String.fromCharCode((v = parseInt(uuid.slice(0, 8), 16)) >>> 24);
    bytes += String.fromCharCode((v >>> 16) & 0xff);
    bytes += String.fromCharCode((v >>> 8) & 0xff);
    bytes += String.fromCharCode(v & 0xff);

    // Parse ........-####-....-....-............
    bytes += String.fromCharCode((v = parseInt(uuid.slice(9, 13), 16)) >>> 8);
    bytes += String.fromCharCode(v & 0xff);

    // Parse ........-....-####-....-............
    bytes += String.fromCharCode((v = parseInt(uuid.slice(14, 18), 16)) >>> 8);
    bytes += String.fromCharCode(v & 0xff);

    // Parse ........-....-....-####-............
    bytes += String.fromCharCode((v = parseInt(uuid.slice(19, 23), 16)) >>> 8);
    bytes += String.fromCharCode(v & 0xff);

    // Parse ........-....-....-....-############
    // (Use "/" to avoid 32-bit truncation when bit-shifting high-order bytes)
    bytes += String.fromCharCode(((v = parseInt(uuid.slice(24, 36), 16)) / 0x10000000000) & 0xff);
    bytes += String.fromCharCode((v / 0x100000000) & 0xff);
    bytes += String.fromCharCode((v >>> 24) & 0xff);
    bytes += String.fromCharCode((v >>> 16) & 0xff);
    bytes += String.fromCharCode((v >>> 8) & 0xff);
    bytes += String.fromCharCode(v & 0xff);

    return btoa(bytes)
        .replaceAll('/', '_') // Replace / with _ (see RFC 4648, sec. 5)
        .replaceAll('+', '-') // Replace + with - (see RFC 4648, sec. 5)
        .substring(0, 22); // Drop '==' padding 
}

export function unpackUUID(bytes: string): string {
    const data = atob(bytes.replaceAll('_', '/').replaceAll('-', '+') + '==');

    return (
        (data.charCodeAt(0) + 0x100).toString(16).slice(1) +
        (data.charCodeAt(1) + 0x100).toString(16).slice(1) +
        (data.charCodeAt(2) + 0x100).toString(16).slice(1) +
        (data.charCodeAt(3) + 0x100).toString(16).slice(1) +
        '-' +
        (data.charCodeAt(4) + 0x100).toString(16).slice(1) +
        (data.charCodeAt(5) + 0x100).toString(16).slice(1) +
        '-' +
        (data.charCodeAt(6) + 0x100).toString(16).slice(1) +
        (data.charCodeAt(7) + 0x100).toString(16).slice(1) +
        '-' +
        (data.charCodeAt(8) + 0x100).toString(16).slice(1) +
        (data.charCodeAt(9) + 0x100).toString(16).slice(1) +
        '-' +
        (data.charCodeAt(10) + 0x100).toString(16).slice(1) +
        (data.charCodeAt(11) + 0x100).toString(16).slice(1) +
        (data.charCodeAt(12) + 0x100).toString(16).slice(1) +
        (data.charCodeAt(13) + 0x100).toString(16).slice(1) +
        (data.charCodeAt(14) + 0x100).toString(16).slice(1) +
        (data.charCodeAt(15) + 0x100).toString(16).slice(1)
    );
}

function test() {
  for (let n = 0; n < 30000; n++) {
    const uuid = crypto.randomUUID();
    const compressed = packUUID(uuid);
    const uncompresed = unpackUUID(compressed)

    if (uuid !== uncompresed) {
        console.log(uuid, compressed, uncompresed, uuid === uncompresed);
    }
  }

  console.log('👌');
}