runmd.onRequire = (path) => {
  if (path == 'rng') return fun;
  return path.replace(/^uuid/, './dist/');
};

// Shim Date and crypto so generated ids are consistent across doc revisions
runmd.Date.now = () => 1551914748172;

let seed = 0xdefaced;
require('crypto').randomFillSync = function (a) {
  for (let i = 0; i < 16; i++) a[i] = (seed = (seed * 0x41a7) & 0x7fffffff) & 0xff;
  return a;
};

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, 14
- 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

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

ECMAScript Module syntax:

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

CommonJS syntax:

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

Create Version 1 (Timestamp) UUIDs

import { v1 as uuidv1 } from 'uuid';
uuidv1(); // RESULT

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); // RESULT
uuidv3('hello.example.com', uuidv3.DNS); // RESULT

// Using predefined URL namespace (for URLs)
uuidv5('http://example.com/hello', uuidv5.URL); // RESULT
uuidv3('http://example.com/hello', uuidv3.URL); // RESULT

// 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); // RESULT
uuidv3('Hello, World!', MY_NAMESPACE); // RESULT

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); // RESULT

Example: Generate two IDs in a single buffer

const buffer = new Array();
uuidv4(null, buffer, 0); // RESULT
uuidv4(null, buffer, 16); // RESULT

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); // RESULT

Example: In-place generation of two binary IDs

// Generate two ids in an array
const arr = new Array();
uuidv1(null, arr, 0); // RESULT
uuidv1(null, arr, 16); // RESULT

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); // RESULT

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); // RESULT

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

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

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

Install react-native-get-random-values
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@7

Only Named Exports Supported When Using with Node.js ESM

uuid@7 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 uuid@7 are no longer supported.

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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README_js.md

README_js.md

uuid

Quickstart

Create Version 4 (Random) UUIDs

Create Version 1 (Timestamp) UUIDs

Create Version 3 or Version 5 (Namespace) UUIDs

API

Version 4 (Random)

Version 1 (Timestamp)

Version 5 (Namespace)

Version 3 (Namespace)

Command Line

ECMAScript Modules

UMD Builds

"getRandomValues() not supported"

React Native

Web Workers / Service Workers (Edge <= 18)

Upgrading From uuid@7

Only Named Exports Supported When Using with Node.js ESM

Deep Requires No Longer Supported

Upgrading From uuid@3

Deep Requires Now Deprecated

Default Export Removed

Files

README_js.md

Latest commit

History

README_js.md

File metadata and controls

uuid

Quickstart

Create Version 4 (Random) UUIDs

Create Version 1 (Timestamp) UUIDs

Create Version 3 or Version 5 (Namespace) UUIDs

API

Version 4 (Random)

Version 1 (Timestamp)

Version 5 (Namespace)

Version 3 (Namespace)

Command Line

ECMAScript Modules

UMD Builds

"getRandomValues() not supported"

React Native

Web Workers / Service Workers (Edge <= 18)

Upgrading From uuid@7

Only Named Exports Supported When Using with Node.js ESM

Deep Requires No Longer Supported

Upgrading From uuid@3

Deep Requires Now Deprecated

Default Export Removed