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Generate RFC-compliant UUIDs in JavaScript

uuidjs
uuidjs
pushedAt 2 hours ago

uuidjs/uuid

uuid CI Browser

For the creation of RFC4122 UUIDs

  • Complete - Support for RFC4122 version 1, 3, 4, and 5 UUIDs
  • Cross-platform - Support for ...
  • 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 [email protected]? Your code is probably okay, but check out Upgrading From [email protected] for details.

Quickstart

To create a random UUID...

1. Install

npm install uuid

2. Create a UUID (ES6 module syntax)

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

... or using CommonJS syntax:

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

For timestamp UUIDs, namespace UUIDs, and other options read on ...

API Summary

uuid.NIL The nil UUID string (all zeros) New in [email protected]
uuid.parse() Convert UUID string to array of bytes New in [email protected]
uuid.stringify() Convert array of bytes to UUID string New in [email protected]
uuid.v1() Create a version 1 (timestamp) UUID
uuid.v3() Create a version 3 (namespace w/ MD5) UUID
uuid.v4() Create a version 4 (random) UUID
uuid.v5() Create a version 5 (namespace w/ SHA-1) UUID
uuid.validate() Test a string to see if it is a valid UUID New in [email protected]
uuid.version() Detect RFC version of a UUID New in [email protected]

API

uuid.NIL

The nil UUID string (all zeros).

Example:

import { NIL as NIL_UUID } from 'uuid';

NIL_UUID; // ⇨ '00000000-0000-0000-0000-000000000000'

uuid.parse(str)

Convert UUID string to array of bytes

str A valid UUID String
returns Uint8Array[16]
throws TypeError if str is not a valid UUID

Note: Ordering of values in the byte arrays used by parse() and stringify() follows the left ↠ right order of hex-pairs in UUID strings. As shown in the example below.

Example:

import { parse as uuidParse } from 'uuid';

// Parse a UUID
const bytes = uuidParse('6ec0bd7f-11c0-43da-975e-2a8ad9ebae0b');

// Convert to hex strings to show byte order (for documentation purposes)
[...bytes].map((v) => v.toString(16).padStart(2, '0')); // ⇨ 
  // [
  //   '6e', 'c0', 'bd', '7f',
  //   '11', 'c0', '43', 'da',
  //   '97', '5e', '2a', '8a',
  //   'd9', 'eb', 'ae', '0b'
  // ]

uuid.stringify(arr[, offset])

Convert array of bytes to UUID string

arr Array-like collection of 16 values (starting from offset) between 0-255.
[offset = 0] Number Starting index in the Array
returns String
throws TypeError if a valid UUID string cannot be generated

Note: Ordering of values in the byte arrays used by parse() and stringify() follows the left ↠ right order of hex-pairs in UUID strings. As shown in the example below.

Example:

import { stringify as uuidStringify } from 'uuid';

const uuidBytes = [
  0x6e, 0xc0, 0xbd, 0x7f, 0x11, 0xc0, 0x43, 0xda, 0x97, 0x5e, 0x2a, 0x8a, 0xd9, 0xeb, 0xae, 0x0b,
];

uuidStringify(uuidBytes); // ⇨ '6ec0bd7f-11c0-43da-975e-2a8ad9ebae0b'

uuid.v1([options[, buffer[, offset]]])

Create an RFC version 1 (timestamp) UUID

[options] Object with one or more of the following properties:
[options.node ] RFC "node" field as an Array[6] of byte values (per 4.1.6)
[options.clockseq] RFC "clock sequence" as a Number between 0 - 0x3fff
[options.msecs] RFC "timestamp" field (Number of milliseconds, unix epoch)
[options.nsecs] RFC "timestamp" field (Number of nanseconds to add to msecs, should be 0-10,000)
[options.random] Array of 16 random bytes (0-255)
[options.rng] Alternative to options.random, a Function that returns an Array of 16 random bytes (0-255)
[buffer] Array | Buffer If specified, uuid will be written here in byte-form, starting at offset
[offset = 0] Number Index to start writing UUID bytes in buffer
returns UUID String if no buffer is specified, otherwise returns buffer
throws Error if more than 10M UUIDs/sec are requested

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.

Note: options.random and options.rng are only meaningful on the very first call to v1(), where they may be passed to initialize the internal node and clockseq fields.

Example:

import { v1 as uuidv1 } from 'uuid';

uuidv1(); // ⇨ '2c5ea4c0-4067-11e9-8bad-9b1deb4d3b7d'

Example using options:

import { v1 as uuidv1 } from 'uuid';

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'

uuid.v3(name, namespace[, buffer[, offset]])

Create an RFC version 3 (namespace w/ MD5) UUID

API is identical to v5(), but uses "v3" instead.

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

uuid.v4([options[, buffer[, offset]]])

Create an RFC version 4 (random) UUID

[options] Object with one or more of the following properties:
[options.random] Array of 16 random bytes (0-255)
[options.rng] Alternative to options.random, a Function that returns an Array of 16 random bytes (0-255)
[buffer] Array | Buffer If specified, uuid will be written here in byte-form, starting at offset
[offset = 0] Number Index to start writing UUID bytes in buffer
returns UUID String if no buffer is specified, otherwise returns buffer

Example:

import { v4 as uuidv4 } from 'uuid';

uuidv4(); // ⇨ '1b9d6bcd-bbfd-4b2d-9b5d-ab8dfbbd4bed'

Example using predefined random values:

import { v4 as uuidv4 } from 'uuid';

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'

uuid.v5(name, namespace[, buffer[, offset]])

Create an RFC version 5 (namespace w/ SHA-1) UUID

name String | Array
namespace String | Array[16] Namespace UUID
[buffer] Array | Buffer If specified, uuid will be written here in byte-form, starting at offset
[offset = 0] Number Index to start writing UUID bytes in buffer
returns UUID String if no buffer is specified, otherwise returns buffer

Note: The RFC DNS and URL namespaces are available as v5.DNS and v5.URL.

Example with custom namespace:

import { v5 as uuidv5 } from 'uuid';

// Define a custom namespace.  Readers, create your own using something like
// https://www.uuidgenerator.net/
const MY_NAMESPACE = '1b671a64-40d5-491e-99b0-da01ff1f3341';

uuidv5('Hello, World!', MY_NAMESPACE); // ⇨ '630eb68f-e0fa-5ecc-887a-7c7a62614681'

Example with RFC URL namespace:

import { v5 as uuidv5 } from 'uuid';

uuidv5('https://www.w3.org/', uuidv5.URL); // ⇨ 'c106a26a-21bb-5538-8bf2-57095d1976c1'

uuid.validate(str)

Test a string to see if it is a valid UUID

str String to validate
returns true if string is a valid UUID, false otherwise

Example:

import { validate as uuidValidate } from 'uuid';

uuidValidate('not a UUID'); // ⇨ false
uuidValidate('6ec0bd7f-11c0-43da-975e-2a8ad9ebae0b'); // ⇨ true

Using validate and version together it is possible to do per-version validation, e.g. validate for only v4 UUIds.

import { version as uuidVersion } from 'uuid';
import { validate as uuidValidate } from 'uuid';

function uuidValidateV4(uuid) {
  return uuidValidate(uuid) && uuidVersion(uuid) === 4;
}

const v1Uuid = 'd9428888-122b-11e1-b85c-61cd3cbb3210';
const v4Uuid = '109156be-c4fb-41ea-b1b4-efe1671c5836';

uuidValidateV4(v4Uuid); // ⇨ true
uuidValidateV4(v1Uuid); // ⇨ false

uuid.version(str)

Detect RFC version of a UUID

str A valid UUID String
returns Number The RFC version of the UUID
throws TypeError if str is not a valid UUID

Example:

import { version as uuidVersion } from 'uuid';

uuidVersion('45637ec4-c85f-11ea-87d0-0242ac130003'); // ⇨ 1
uuidVersion('6ec0bd7f-11c0-43da-975e-2a8ad9ebae0b'); // ⇨ 4

Command Line

UUIDs can be generated from the command line using uuid.

$ npx 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:

$ npx 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

This library comes with ECMAScript Modules (ESM) support for Node.js versions that support it (example) as well as bundlers like rollup.js (example) and webpack (example) (targeting both, Node.js and browser environments).

import { v4 as uuidv4 } from 'uuid';
uuidv4(); // ⇨ '1b9d6bcd-bbfd-4b2d-9b5d-ab8dfbbd4bed'

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

npm run build

CDN Builds

ECMAScript Modules

To load this module directly into modern browsers that support loading ECMAScript Modules you can make use of jspm:

<script type="module">
  import { v4 as uuidv4 } from 'https://jspm.dev/uuid';
  console.log(uuidv4()); // ⇨ '1b9d6bcd-bbfd-4b2d-9b5d-ab8dfbbd4bed'
</script>

UMD

To load this module directly into older browsers you can use the UMD (Universal Module Definition) builds from any of the following CDNs:

Using UNPKG:

<script src="https://unpkg.com/[email protected]/dist/umd/uuidv4.min.js"></script>

Using jsDelivr:

<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/umd/uuidv4.min.js"></script>

Using cdnjs:

<script src="https://cdnjs.cloudflare.com/ajax/libs/uuid/8.1.0/uuidv4.min.js"></script>

These CDNs all provide the same uuidv4() method:

<script>
  uuidv4(); // ⇨ '55af1e37-0734-46d8-b070-a1e42e4fc392'
</script>

Methods for the other algorithms (uuidv1(), uuidv3() and uuidv5()) are available from the files uuidv1.min.js, uuidv3.min.js and uuidv5.min.js respectively.

Known issues

Duplicate UUIDs (Googlebot)

This module may generate duplicate UUIDs when run in clients with deterministic random number generators, such as Googlebot crawlers. This can cause problems for apps that expect client-generated UUIDs to always be unique. Developers should be prepared for this and have a strategy for dealing with possible collisions, such as:

  • Check for duplicate UUIDs, fail gracefully
  • Disable write operations for Googlebot clients

"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 / Expo

  1. Install react-native-get-random-values
  2. Import it before uuid. Since uuid might also appear as a transitive dependency of some other imports it's safest to just import react-native-get-random-values as the very first thing in your entry point:
import 'react-native-get-random-values';
import { v4 as uuidv4 } from 'uuid';

Note: If you are using Expo, you must be using at least [email protected] and [email protected].

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 [email protected]

Only Named Exports Supported When Using with Node.js ESM

[email protected] did not come with native ECMAScript Module (ESM) support for Node.js. Importing it in Node.js ESM consequently imported the CommonJS source with a default export. This library now comes with true Node.js ESM support and only provides named exports.

Instead of doing:

import uuid from 'uuid';
uuid.v4();

you will now have to use the named exports:

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

Deep Requires No Longer Supported

Deep requires like require('uuid/v4') which have been deprecated in [email protected] are no longer supported.

Upgrading From [email protected]

"Wait... what happened to [email protected] thru [email protected]?!?"

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.

Deep Requires Now Deprecated

[email protected] encouraged the use of deep requires to minimize the bundle size of browser builds:

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

As of [email protected] 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

[email protected] was exporting the Version 4 UUID method as a default export:

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

This usage pattern was already discouraged in [email protected] and has been removed in [email protected].


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