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uuid Build Status

Simple, fast generation of RFC4122 UUIDs.

Features:

  • Support for version 1, 3, 4 and 5 UUIDs
  • Cross-platform: CommonJS build for Node.js and ECMAScript Modules for the browser.
  • Uses cryptographically-strong random number APIs
  • Zero-dependency, small footprint

Quickstart - Node.js/CommonJS

npm install uuid

Then generate a random UUID (v4 algorithm), which is almost always what you want ...

Version 4 (random):

const uuid = require('uuid');
uuid.v4(); // ⇨ '9b1deb4d-3b7d-4bad-9bdd-2b0d7b3dcb6d'

Or generate UUIDs with other algorithms of your choice ...

Version 1 (timestamp):

const uuid = require('uuid');
uuid.v1(); // ⇨ '2c5ea4c0-4067-11e9-8b2d-1b9d6bcdbbfd'

Version 3 (namespace):

const uuid = require('uuid');

// ... using predefined DNS namespace (for domain names)
uuid.v3('hello.example.com', uuid.v3.DNS); // ⇨ '9125a8dc-52ee-365b-a5aa-81b0b3681cf6'

// ... using predefined URL namespace (for, well, URLs)
uuid.v3('http://example.com/hello', uuid.v3.URL); // ⇨ 'c6235813-3ba4-3801-ae84-e0a6ebb7d138'

// ... using a custom namespace
//
// Note: Custom namespaces should be a UUID string specific to your application!
// E.g. the one here was generated using this modules `uuid` CLI.
const MY_NAMESPACE = '1b671a64-40d5-491e-99b0-da01ff1f3341';
uuid.v3('Hello, World!', MY_NAMESPACE); // ⇨ 'e8b5a51d-11c8-3310-a6ab-367563f20686'

Version 5 (namespace):

const uuid = require('uuid');

// ... using predefined DNS namespace (for domain names)
uuid.v5('hello.example.com', uuid.v5.DNS); // ⇨ 'fdda765f-fc57-5604-a269-52a7df8164ec'

// ... using predefined URL namespace (for, well, URLs)
uuid.v5('http://example.com/hello', uuid.v5.URL); // ⇨ '3bbcee75-cecc-5b56-8031-b6641c1ed1f1'

// ... using a custom namespace
//
// Note: Custom namespaces should be a UUID string specific to your application!
// E.g. the one here was generated using this modules `uuid` CLI.
const MY_NAMESPACE = '1b671a64-40d5-491e-99b0-da01ff1f3341';
uuid.v5('Hello, World!', MY_NAMESPACE); // ⇨ '630eb68f-e0fa-5ecc-887a-7c7a62614681'

Supported Platforms

  • Node.js: All LTS, i.e. 8.x, 10.x, 12.x
  • Browsers (with bundlers like webpack/rollup):
    • Chrome: >= 49
    • Safari: >= 10
    • Firefox: >= 44
    • Edge: >= 15
    • IE: 11

ECMAScript Modules / ESM

For usage in the browser uuid provides support for ECMAScript Modules (ESM) that enable tree-shaking for bundlers, like rollup.js (example) and webpack (example).

import { v4 as uuid } from 'uuid';
uuid(); // ⇨ '1b9d6bcd-bbfd-4b2d-9b5d-ab8dfbbd4bed'

There is experimental native ESM support for the browser but it should not be considered ready for production use and may change or disappear in future releases.

To run the examples you must first create a dist build of this library in the module root:

npm run build

API

Version 4 (Random)

const uuid = require('uuid');

// Incantations
uuid.v4();
uuid.v4(options);
uuid.v4(options, buffer, offset);

Generate and return a RFC4122 v4 UUID.

  • options - (Object) Optional uuid state to apply. Properties may include:
    • random - (Number[16]) Array of 16 numbers (0-255) to use in place of randomly generated values. Takes precedence over options.rng.
    • rng - (Function) Random # generator function that returns an Array[16] of byte values (0-255). Alternative to options.random.
  • buffer - (Array | Buffer) Array or buffer where UUID bytes are to be written.
  • offset - (Number) Starting index in buffer at which to begin writing.

Returns buffer, if specified, otherwise the string form of the UUID

Example: Generate string UUID with predefined random values

const v4options = {
  random: [
    0x10,
    0x91,
    0x56,
    0xbe,
    0xc4,
    0xfb,
    0xc1,
    0xea,
    0x71,
    0xb4,
    0xef,
    0xe1,
    0x67,
    0x1c,
    0x58,
    0x36,
  ],
};
uuid.v4(v4options); // ⇨ '109156be-c4fb-41ea-b1b4-efe1671c5836'

Example: Generate two IDs in a single buffer

const buffer = new Array();
uuid.v4(null, buffer, 0); // ⇨ 
  // [
  //   155, 29, 235,  77,  59,
  //   125, 75, 173, 155, 221,
  //    43, 13, 123,  61, 203,
  //   109
  // ]
uuid.v4(null, buffer, 16); // ⇨ 
  // [
  //   155,  29, 235,  77,  59, 125,  75, 173,
  //   155, 221,  43,  13, 123,  61, 203, 109,
  //    27, 157, 107, 205, 187, 253,  75,  45,
  //   155,  93, 171, 141, 251, 189,  75, 237
  // ]

Version 1 (Timestamp + Node)

⚠️⚠️⚠️ Please make sure to check whether you really need the timestamp properties of Version 1 UUIDs before using them. In many cases, Version 4 random UUIDs are the better choice. This FAQ covers more details. ⚠️⚠️⚠️

const uuid = require('uuid');

// Incantations
uuid.v1();
uuid.v1(options);
uuid.v1(options, buffer, offset);

Generate and return a RFC4122 v1 (timestamp-based) UUID.

  • options - (Object) Optional uuid state to apply. Properties may include:
    • node - (Array) Node id as Array of 6 bytes (per 4.1.6). Default: Randomly generated ID. See note 1.
    • clockseq - (Number between 0 - 0x3fff) RFC clock sequence. Default: An internally maintained clockseq is used.
    • msecs - (Number) Time in milliseconds since unix Epoch. Default: The current time is used.
    • nsecs - (Number between 0-9999) additional time, in 100-nanosecond units. Ignored if msecs is unspecified. Default: internal uuid counter is used, as per 4.2.1.2.
    • random - (Number[16]) Array of 16 numbers (0-255) to use for initialization of node and clockseq as described above. Takes precedence over options.rng.
    • rng - (Function) Random # generator function that returns an Array[16] of byte values (0-255). Alternative to options.random.
  • buffer - (Array | Buffer) Array or buffer where UUID bytes are to be written.
  • offset - (Number) Starting index in buffer at which to begin writing.

Returns buffer, if specified, otherwise the string form of the UUID

Note: The default node id (the last 12 digits in the UUID) is generated once, randomly, on process startup, and then remains unchanged for the duration of the process.

Example: Generate string UUID with fully-specified options

const v1options = {
  node: [0x01, 0x23, 0x45, 0x67, 0x89, 0xab],
  clockseq: 0x1234,
  msecs: new Date('2011-11-01').getTime(),
  nsecs: 5678,
};
uuid.v1(v1options); // ⇨ '710b962e-041c-11e1-9234-0123456789ab'

Example: In-place generation of two binary IDs

// Generate two ids in an array
const arr = new Array();
uuid.v1(null, arr, 0); // ⇨ 
  // [
  //    44,  94, 164, 192,  64,
  //   103,  17, 233, 146,  52,
  //    27, 157, 107, 205, 187,
  //   253
  // ]
uuid.v1(null, arr, 16); // ⇨ 
  // [
  //    44, 94, 164, 192,  64, 103,  17, 233,
  //   146, 52,  27, 157, 107, 205, 187, 253,
  //    44, 94, 164, 193,  64, 103,  17, 233,
  //   146, 52,  27, 157, 107, 205, 187, 253
  // ]

Version 3 (Namespace)

const uuid = require('uuid');

// Incantations
uuid.v3(name, namespace);
uuid.v3(name, namespace, buffer);
uuid.v3(name, namespace, buffer, offset);

Generate and return a RFC4122 v3 UUID.

  • name - (String | Array[]) "name" to create UUID with
  • namespace - (String | Array[]) "namespace" UUID either as a String or Array[16] of byte values
  • buffer - (Array | Buffer) Array or buffer where UUID bytes are to be written.
  • offset - (Number) Starting index in buffer at which to begin writing. Default = 0

Returns buffer, if specified, otherwise the string form of the UUID

Example:

uuid.v3('hello world', MY_NAMESPACE); // ⇨ '042ffd34-d989-321c-ad06-f60826172424'

Version 5 (Namespace)

const uuid = require('uuid');

// Incantations
uuid.v5(name, namespace);
uuid.v5(name, namespace, buffer);
uuid.v5(name, namespace, buffer, offset);

Generate and return a RFC4122 v5 UUID.

  • name - (String | Array[]) "name" to create UUID with
  • namespace - (String | Array[]) "namespace" UUID either as a String or Array[16] of byte values
  • buffer - (Array | Buffer) Array or buffer where UUID bytes are to be written.
  • offset - (Number) Starting index in buffer at which to begin writing. Default = 0

Returns buffer, if specified, otherwise the string form of the UUID

Example:

uuid.v5('hello world', MY_NAMESPACE); // ⇨ '9f282611-e0fd-5650-8953-89c8e342da0b'

Command Line

UUIDs can be generated from the command line with the uuid command.

$ uuid
ddeb27fb-d9a0-4624-be4d-4615062daed4

$ uuid v1
02d37060-d446-11e7-a9fa-7bdae751ebe1

Type uuid --help for usage details

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