Node.js UUID

Файл uuid.js:

var crypto = require('crypto');

function rng () {
    return crypto.randomBytes(16);
}

/**
 * Convert array of 16 byte values to UUID string format of the form:
 * XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX
 */
var byteToHex = [];
for (var i = 0; i < 256; ++i) {
    byteToHex[i] = (i + 0x100).toString(16).substr(1);
}

function bytesToUuid (buf, offset) {
    var i = offset || 0;
    var bth = byteToHex;
    // join used to fix memory issue caused by concatenation: https://bugs.chromium.org/p/v8/issues/detail?id=3175#c4
    return [
        bth[buf[i++]], bth[buf[i++]],
        bth[buf[i++]], bth[buf[i++]], '-',
        bth[buf[i++]], bth[buf[i++]], '-',
        bth[buf[i++]], bth[buf[i++]], '-',
        bth[buf[i++]], bth[buf[i++]], '-',
        bth[buf[i++]], bth[buf[i++]],
        bth[buf[i++]], bth[buf[i++]],
        bth[buf[i++]], bth[buf[i++]]
    ].join('');
}

function uuid (options, buf, offset) {
    var i = buf && offset || 0;

    if (typeof options === 'string') {
        buf = options === 'binary' ? new Array(16) : null;
        options = null;
    }
    options = options || {};

    var rnds = options.random || (options.rng || rng)();

    // Per 4.4, set bits for version and `clock_seq_hi_and_reserved`
    rnds[6] = (rnds[6] & 0x0f) | 0x40;
    rnds[8] = (rnds[8] & 0x3f) | 0x80;

    // Copy bytes to buffer, if provided
    if (buf) {
        for (var ii = 0; ii < 16; ++ii) {
            buf[i + ii] = rnds[ii];
        }
    }

    return buf || bytesToUuid(rnds);
}

Файл index.js:

var uuid = require('./uuid');

console.log(uuid());

module.exports = uuid;