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

For the creation of RFC4122 UUIDs

• Complete - Support for RFC4122 version 1, 3, 4, and 5 UUIDs
• Cross-platform - Support for ...
  • CommonJS, ECMAScript Modules and UMD builds
  • Node 8, 10, 12
  • Chrome, Safari, Firefox, Edge, IE 11 browsers
  • Webpack and rollup.js module bundlers
  • React Native
• Secure - Cryptographically-strong random values
• Small - Zero-dependency, small footprint, plays nice with "tree shaking" packagers
• CLI - Includes the uuid command line utility

Upgrading from uuid@3? Your code is probably okay, but check out Upgrading From uuid@3 for details.

Quickstart - Node.js/CommonJS

npm install uuid

Once installed, decide which type of UUID you need. RFC4122 provides for four versions, all of which are supported here. In order of popularity, they are:

• Version 4 (random) - Created from cryptographically-strong random values
• Version 1 (timestamp) - Created from the system clock (plus random values)
• Version 5 (namespace, SHA-1) - Created from user-supplied name and namespace strings
• Version 3 (namespace, MD5) - Like version 5, above, but with a poorer hash algorithm

Unsure which one to use? Use version 4 (random) unless you have a specific need for one of the other versions. See also this FAQ.

Create Version 4 (Random) UUIDs

import { v4 as uuidv4 } from 'uuid';
uuidv4(); // ⇨ '9b1deb4d-3b7d-4bad-9bdd-2b0d7b3dcb6d'

Create Version 1 (Timestamp) UUIDs

import { v1 as uuidv1 } from 'uuid';
uuidv1(); // ⇨ '2c5ea4c0-4067-11e9-8b2d-1b9d6bcdbbfd'

Create Version 3 or Version 5 (Namespace) UUIDs

⚠️ Version 3 and Version 5 UUIDs are basically the same, differing only in the underlying hash algorithm. Note that per the RFC, "If backward compatibility is not an issue, SHA-1 [Version 5] is preferred."

⚠️ If using a custom namespace be sure to generate your own namespace UUID. You can grab one here.

import { v5 as uuidv5 } from 'uuid'; // For version 5
import { v3 as uuidv3 } from 'uuid'; // For version 3

// Using predefined DNS namespace (for domain names)
uuidv5('hello.example.com', uuidv5.DNS); // ⇨ 'fdda765f-fc57-5604-a269-52a7df8164ec'
uuidv3('hello.example.com', uuidv3.DNS); // ⇨ '9125a8dc-52ee-365b-a5aa-81b0b3681cf6'

// Using predefined URL namespace (for URLs)
uuidv5('http://example.com/hello', uuidv5.URL); // ⇨ '3bbcee75-cecc-5b56-8031-b6641c1ed1f1'
uuidv3('http://example.com/hello', uuidv3.URL); // ⇨ 'c6235813-3ba4-3801-ae84-e0a6ebb7d138'

// Using a custom namespace (See note, above, about generating your own
// namespace UUID)
const MY_NAMESPACE = '1b671a64-40d5-491e-99b0-da01ff1f3341';
uuidv5('Hello, World!', MY_NAMESPACE); // ⇨ '630eb68f-e0fa-5ecc-887a-7c7a62614681'
uuidv3('Hello, World!', MY_NAMESPACE); // ⇨ 'e8b5a51d-11c8-3310-a6ab-367563f20686'

API

Version 4 (Random)

import { v4 as uuidv4 } from 'uuid';

// Incantations
uuidv4();
uuidv4(options);
uuidv4(options, buffer, offset);

Generate and return a RFC4122 version 4 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,
  ],
};
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 1 (Timestamp)

import { v1 as uuidv1 } from 'uuid';

// Incantations
uuidv1();
uuidv1(options);
uuidv1(options, buffer, offset);

Generate and return a RFC4122 version 1 (timestamp) 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,
};
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,
  //    27, 157, 107, 205, 187,
  //   253
  // ]
uuidv1(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 5 (Namespace)

import { v5 as uuidv5 } from 'uuid';

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

Generate and return a RFC4122 version 5 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'

Version 3 (Namespace)

⚠️ Note: Per the RFC, "If backward compatibility is not an issue, SHA-1 [Version 5] is preferred."

import { v3 as uuidv3 } from 'uuid';

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

Generate and return a RFC4122 version 3 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'

Command Line

UUIDs can be generated from the command line using uuid.

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

The default is to generate version 4 UUIDS, however the other versions are supported. Type uuid --help for details:

$ uuid --help

Usage:
  uuid
  uuid v1
  uuid v3 <name> <namespace uuid>
  uuid v4
  uuid v5 <name> <namespace uuid>
  uuid --help

Note: <namespace uuid> may be "URL" or "DNS" to use the corresponding UUIDs
defined by RFC4122

ECMAScript Modules

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 uuidv4 } from 'uuid';
uuidv4(); // ⇨ '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

UMD Builds

If you want to load a minified UMD build directly in the browser you can use one of the popular npm CDNs:

<script src="https://unpkg.com/uuid@latest/dist/umd/uuidv4.min.js"></script>
<script>
  alert(uuidv4());
</script>

or

<script src="https://cdn.jsdelivr.net/npm/uuid@latest/dist/umd/uuidv4.min.js"></script>
<script>
  alert(uuidv4());
</script>

Available bundles:

• https://unpkg.com/uuid@latest/dist/umd/
• https://cdn.jsdelivr.net/npm/uuid@latest/dist/umd/

"getRandomValues() not supported"

This error occurs in environments where the standard crypto.getRandomValues() API is not supported. This issue can be resolved by adding an appropriate polyfill:

React Native

1. Install react-native-get-random-values
2. Import it before uuid:

import 'react-native-get-random-values';
import { v4 as uuidv4 } from 'uuid';

Web Workers / Service Workers (Edge <= 18)

In Edge <= 18, Web Crypto is not supported in Web Workers or Service Workers and we are not aware of a polyfill (let us know if you find one, please).

Upgrading From uuid@3

"Wait... what happened to uuid@4 - uuid@6?!?"

In order to avoid confusion with RFC version 4 and version 5 UUIDs, and a possible version 6, releases 4 thru 6 of this module have been skipped. Hence, how we're now at uuid@7.

Deep Requires Now Deprecated

uuid@3 encouraged the use of deep requires to minimize the bundle size of browser builds:

const uuidv4 = require('uuid/v4'); // <== NOW DEPRECATED!
uuidv4();

As of uuid@7 this library now provides ECMAScript modules builds, which allow packagers like Webpack and Rollup to do "tree-shaking" to remove dead code. Instead, use the import syntax:

import { v4 as uuidv4 } from 'uuid';
uuidv4();

... or for CommonJS:

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

Default Export Removed

uuid@3 was exporting the Version 4 UUID method as a default export:

const uuid = require('uuid'); // <== REMOVED!

This usage pattern was already discouraged in uuid@3 and has been removed in uuid@7.

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Markdown generated from README_js.md by

Changelog

7.0.3 (2020-03-31)

Bug Fixes

• make deep require deprecation warning work in browsers (#409) (4b71107), closes #408