uuid

What is uuid?

The uuid npm package is used to generate universally unique identifiers (UUIDs), which are 128-bit numbers used to uniquely identify information in computer systems. The package supports multiple versions of UUIDs, each with different methods of generation based on requirements such as randomness, time-based generation, and name-based generation using namespaces.

What are uuid's main functionalities?

Generate UUID v1

Generates a version 1 UUID based on timestamp and MAC address of the host machine, ensuring temporal uniqueness.

const { v1: uuidv1 } = require('uuid');
console.log(uuidv1());

Generate UUID v4

Generates a version 4 UUID using random or pseudo-random numbers, providing a higher degree of randomness.

const { v4: uuidv4 } = require('uuid');
console.log(uuidv4());

Generate UUID v3

Generates a version 3 UUID using MD5 hashing of a namespace identifier and a name.

const { v3: uuidv3 } = require('uuid');
const MY_NAMESPACE = '1b671a64-40d5-491e-99b0-da01ff1f3341';
console.log(uuidv3('Hello, World!', MY_NAMESPACE));

Generate UUID v5

Generates a version 5 UUID using SHA-1 hashing of a namespace identifier and a name, providing better uniqueness and lower collision probability than v3.

const { v5: uuidv5 } = require('uuid');
const MY_NAMESPACE = '1b671a64-40d5-491e-99b0-da01ff1f3341';
console.log(uuidv5('Hello, World!', MY_NAMESPACE));

Other packages similar to uuid

shortid

ShortId generates short, non-sequential, URL-friendly unique ids. Unlike uuid, which generates 128-bit long UUIDs, ShortId creates shorter ids, which can be easier to use in URLs or when space is limited. However, ShortId is not recommended for security-critical applications due to the shorter identifier length and lower entropy.

nanoid

NanoId is a tiny, secure, URL-friendly, unique string ID generator for JavaScript. It is similar to uuid v4 in that it provides a way to generate random IDs, but it offers a customizable alphabet and length, allowing for a wider range of possible IDs. NanoId claims to be faster and more compact than UUID, making it a good alternative for many applications.

cuid

CUID (Collision-resistant Unique Identifier) is another alternative for generating unique identifiers. It is designed to be more collision-resistant than uuid and is optimized for horizontal scaling and sequential lookup performance. CUIDs are longer than UUIDs and contain a timestamp, which can be useful for sorting records in a database.

README

uuid

Simple, fast generation of RFC4122 UUIDS.

Features:

• Support for version 1, 3, 4 and 5 UUIDs
• Cross-platform
• Uses cryptographically-strong random number APIs (when available)
• Zero-dependency, small footprint (... but not this small)

[Deprecation warning: The use of require('uuid') is deprecated and will not be supported after version 3.x of this module. Instead, use require('uuid/[v1|v3|v4|v5]') as shown in the examples below.]

Quickstart - CommonJS (Recommended)

npm install uuid

Then generate your uuid version of choice ...

Version 1 (timestamp):

const uuidv1 = require('uuid/v1');
uuidv1(); // ⇨ '2c5ea4c0-4067-11e9-8bad-9b1deb4d3b7d'

Version 3 (namespace):

const uuidv3 = require('uuid/v3');

// ... using predefined DNS namespace (for domain names)
uuidv3('hello.example.com', uuidv3.DNS); // ⇨ '9125a8dc-52ee-365b-a5aa-81b0b3681cf6'

// ... using predefined URL namespace (for, well, URLs)
uuidv3('http://example.com/hello', uuidv3.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';
uuidv3('Hello, World!', MY_NAMESPACE); // ⇨ 'e8b5a51d-11c8-3310-a6ab-367563f20686'

Version 4 (random):

const uuidv4 = require('uuid/v4');
uuidv4(); // ⇨ '1b9d6bcd-bbfd-4b2d-9b5d-ab8dfbbd4bed'

Version 5 (namespace):

const uuidv5 = require('uuid/v5');

// ... using predefined DNS namespace (for domain names)
uuidv5('hello.example.com', uuidv5.DNS); // ⇨ 'fdda765f-fc57-5604-a269-52a7df8164ec'

// ... using predefined URL namespace (for, well, URLs)
uuidv5('http://example.com/hello', uuidv5.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';
uuidv5('Hello, World!', MY_NAMESPACE); // ⇨ '630eb68f-e0fa-5ecc-887a-7c7a62614681'

API

Version 1

const uuidv1 = require('uuid/v1');

// Incantations
uuidv1();
uuidv1(options);
uuidv1(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.

• 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
};
uuidv1(v1options); // ⇨ '710b962e-041c-11e1-9234-0123456789ab'

Example: In-place generation of two binary IDs

// Generate two ids in an array
const arr = new Array();
uuidv1(null, arr, 0);  // ⇨ 
  // [
  //    44,  94, 164, 192,  64, 103,
  //    17, 233, 146,  52, 155,  29,
  //   235,  77,  59, 125
  // ]
uuidv1(null, arr, 16); // ⇨ 
  // [
  //    44, 94, 164, 192,  64, 103, 17, 233,
  //   146, 52, 155,  29, 235,  77, 59, 125,
  //    44, 94, 164, 193,  64, 103, 17, 233,
  //   146, 52, 155,  29, 235,  77, 59, 125
  // ]

Version 3

const uuidv3 = require('uuid/v3');

// Incantations
uuidv3(name, namespace);
uuidv3(name, namespace, buffer);
uuidv3(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:

uuidv3('hello world', MY_NAMESPACE);  // ⇨ '042ffd34-d989-321c-ad06-f60826172424'

Version 4

const uuidv4 = require('uuid/v4')

// Incantations
uuidv4();
uuidv4(options);
uuidv4(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
  • rng - (Function) Random # generator function that returns an Array[16] of byte values (0-255)
• 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
  ]
};
uuidv4(v4options); // ⇨ '109156be-c4fb-41ea-b1b4-efe1671c5836'

Example: Generate two IDs in a single buffer

const buffer = new Array();
uuidv4(null, buffer, 0);  // ⇨ 
  // [
  //   155, 29, 235,  77,  59,
  //   125, 75, 173, 155, 221,
  //    43, 13, 123,  61, 203,
  //   109
  // ]
uuidv4(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 5

const uuidv5 = require('uuid/v5');

// Incantations
uuidv5(name, namespace);
uuidv5(name, namespace, buffer);
uuidv5(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:

uuidv5('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

Testing

npm test

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Changelog

3.4.0 (2020-01-16)

Features

• rename repository to github:uuidjs/uuid (#351) (e2d7314), closes #338