<!--
  -- This file is auto-generated from README_js.md. Changes should be made there.
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# uuid [![CI](https://github.com/uuidjs/uuid/workflows/CI/badge.svg)](https://github.com/uuidjs/uuid/actions?query=workflow%3ACI) [![Browser](https://github.com/uuidjs/uuid/workflows/Browser/badge.svg)](https://github.com/uuidjs/uuid/actions/workflows/browser.yml)

For the creation of [RFC9562](https://www.rfc-editor.org/rfc/rfc9562.html) (formerly [RFC4122](https://www.rfc-editor.org/rfc/rfc4122.html)) UUIDs

- **Complete** - Support for all RFC9562 UUID versions
- **Cross-platform** - Support for...
  - [Typescript](#support)
  - [Chrome, Safari, Firefox, and Edge](#support)
  - [NodeJS](#support)
  - [React Native / Expo](#react-native--expo)
- **Secure** - Uses modern `crypto` API for random values
- **Compact** - Zero-dependency, [tree-shakable](https://developer.mozilla.org/en-US/docs/Glossary/Tree_shaking)
- **CLI** - [`uuid` command line](#command-line) utility

<!-- prettier-ignore -->
> [!NOTE]
>
> Starting with `uuid@12` CommonJS is no longer supported.  See [implications](https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c) and [motivation](https://github.com/uuidjs/uuid/issues/881) for details.

## Quickstart

**1. Install**

```shell
npm install uuid
```

**2. Create a UUID**

```javascript
import { v4 as uuidv4 } from "uuid";

uuidv4(); // ⇨ 'ab16e731-6cee-424d-81a0-5929e9bdb0cc'
```

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

## API Summary

|                                                    |                                                 |                   |
| -------------------------------------------------- | ----------------------------------------------- | ----------------- |
| [`uuid.NIL`](#uuidnil)                             | The nil UUID string (all zeros)                 | New in `uuid@8.3` |
| [`uuid.MAX`](#uuidmax)                             | The max UUID string (all ones)                  | New in `uuid@9.1` |
| [`uuid.parse()`](#uuidparsestr)                    | Convert UUID string to array of bytes           | New in `uuid@8.3` |
| [`uuid.stringify()`](#uuidstringifyarr-offset)     | Convert array of bytes to UUID string           | New in `uuid@8.3` |
| [`uuid.v1()`](#uuidv1options-buffer-offset)        | Create a version 1 (timestamp) UUID             |                   |
| [`uuid.v1ToV6()`](#uuidv1tov6uuid)                 | Create a version 6 UUID from a version 1 UUID   | New in `uuid@10`  |
| [`uuid.v3()`](#uuidv3name-namespace-buffer-offset) | Create a version 3 (namespace w/ MD5) UUID      |                   |
| [`uuid.v4()`](#uuidv4options-buffer-offset)        | Create a version 4 (random) UUID                |                   |
| [`uuid.v5()`](#uuidv5name-namespace-buffer-offset) | Create a version 5 (namespace w/ SHA-1) UUID    |                   |
| [`uuid.v6()`](#uuidv6options-buffer-offset)        | Create a version 6 (timestamp, reordered) UUID  | New in `uuid@10`  |
| [`uuid.v6ToV1()`](#uuidv6tov1uuid)                 | Create a version 1 UUID from a version 6 UUID   | New in `uuid@10`  |
| [`uuid.v7()`](#uuidv7options-buffer-offset)        | Create a version 7 (Unix Epoch time-based) UUID | New in `uuid@10`  |
| ~~[`uuid.v8()`](#uuidv8)~~                         | "Intentionally left blank"                      |                   |
| [`uuid.validate()`](#uuidvalidatestr)              | Test a string to see if it is a valid UUID      | New in `uuid@8.3` |
| [`uuid.version()`](#uuidversionstr)                | Detect RFC version of a UUID                    | New in `uuid@8.3` |

## API

### uuid.NIL

The nil UUID string (all zeros).

Example:

```javascript
import { NIL as NIL_UUID } from "uuid";

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

### uuid.MAX

The max UUID string (all ones).

Example:

```javascript
import { MAX as MAX_UUID } from "uuid";

MAX_UUID; // ⇨ 'ffffffff-ffff-ffff-ffff-ffffffffffff'
```

### 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 |

<!-- prettier-ignore -->
> [!NOTE]
> Ordering of values in the byte arrays used by `parse()` and `stringify()` follows the left &Rarr; right order of hex-pairs in UUID strings. As shown in the example below.

Example:

```javascript
import { parse as uuidParse } from "uuid";

// Parse a UUID
uuidParse("6ec0bd7f-11c0-43da-975e-2a8ad9ebae0b"); // ⇨
// Uint8Array(16) [
//   110, 192, 189, 127,  17,
//   192,  67, 218, 151,  94,
//    42, 138, 217, 235, 174,
//    11
// ]
```

### 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                       |

<!-- prettier-ignore -->
> [!NOTE]
> Ordering of values in the byte arrays used by `parse()` and `stringify()` follows the left &Rarr; right order of hex-pairs in UUID strings. As shown in the example below.

Example:

```javascript
import { stringify as uuidStringify } from "uuid";

const uuidBytes = Uint8Array.of(
  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 = (random)` ]       | RFC "node" field as an `Array[6]` of byte values (per 4.1.6)                                                                           |
| [`options.clockseq = (random)`]    | RFC "clock sequence" as a `Number` between 0 - 0x3fff                                                                                  |
| [`options.msecs = (current time)`] | RFC "timestamp" field (`Number` of milliseconds, unix epoch)                                                                           |
| [`options.nsecs = 0`]              | RFC "timestamp" field (`Number` of nanoseconds to add to `msecs`, should be 0-10,000)                                                  |
| [`options.random = (random)`]      | `Array` of 16 random bytes (0-255) used to generate other fields, above                                                                |
| [`options.rng`]                    | Alternative to `options.random`, a `Function` that returns an `Array` of 16 random bytes (0-255)                                       |
| [`buffer`]                         | `Uint8Array` or `Uint8Array` subtype (e.g. Node.js `Buffer`). If provided, binary UUID is written into the array, 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                                                                                       |

Example:

```javascript
import { v1 as uuidv1 } from "uuid";

uuidv1(); // ⇨ '4d9d2960-31d0-11f1-aba8-29728d41eeed'
```

Example using `options`:

```javascript
import { v1 as uuidv1 } from "uuid";

const options = {
  node: Uint8Array.of(0x01, 0x23, 0x45, 0x67, 0x89, 0xab),
  clockseq: 0x1234,
  msecs: new Date("2011-11-01").getTime(),
  nsecs: 5678,
};
uuidv1(options); // ⇨ '710b962e-041c-11e1-9234-0123456789ab'
```

### uuid.v1ToV6(uuid)

Convert a UUID from version 1 to version 6

```javascript
import { v1ToV6 } from "uuid";

v1ToV6("92f62d9e-22c4-11ef-97e9-325096b39f47"); // ⇨ '1ef22c49-2f62-6d9e-97e9-325096b39f47'
```

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

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

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

<!-- prettier-ignore -->
> [!IMPORTANT]
> 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`]         | `Uint8Array` or `Uint8Array` subtype (e.g. Node.js `Buffer`). If provided, binary UUID is written into the array, 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:

```javascript
import { v4 as uuidv4 } from "uuid";

uuidv4(); // ⇨ '7934256a-bc92-4b69-b240-f9e463881aea'
```

Example using predefined `random` values:

```javascript
import { v4 as uuidv4 } from "uuid";

const v4options = {
  random: Uint8Array.of(
    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`]     | `Uint8Array` or `Uint8Array` subtype (e.g. Node.js `Buffer`). If provided, binary UUID is written into the array, 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`                                                                  |

<!-- prettier-ignore -->
> [!NOTE]
> The RFC `DNS` and `URL` namespaces are available as `v5.DNS` and `v5.URL`.

Example with custom namespace:

```javascript
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:

```javascript
import { v5 as uuidv5 } from "uuid";

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

### uuid.v6([options[, buffer[, offset]]])

Create an RFC version 6 (timestamp, reordered) UUID

This method takes the same arguments as uuid.v1().

```javascript
import { v6 as uuidv6 } from "uuid";

uuidv6(); // ⇨ '1f131d04-d9dc-65a0-9516-5be66631ce97'
```

Example using `options`:

```javascript
import { v6 as uuidv6 } from "uuid";

const options = {
  node: [0x01, 0x23, 0x45, 0x67, 0x89, 0xab],
  clockseq: 0x1234,
  msecs: new Date("2011-11-01").getTime(),
  nsecs: 5678,
};
uuidv6(options); // ⇨ '1e1041c7-10b9-662e-9234-0123456789ab'
```

### uuid.v6ToV1(uuid)

Convert a UUID from version 6 to version 1

```javascript
import { v6ToV1 } from "uuid";

v6ToV1("1ef22c49-2f62-6d9e-97e9-325096b39f47"); // ⇨ '92f62d9e-22c4-11ef-97e9-325096b39f47'
```

### uuid.v7([options[, buffer[, offset]]])

Create an RFC version 7 (random) UUID

|                                    |                                                                                                                                                                                        |
| ---------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| [`options`]                        | `Object` with one or more of the following properties:                                                                                                                                 |
| [`options.msecs = (current time)`] | RFC "timestamp" field (`Number` of milliseconds, unix epoch)                                                                                                                           |
| [`options.random = (random)`]      | `Array` of 16 random bytes (0-255) used to generate other fields, above                                                                                                                |
| [`options.rng`]                    | Alternative to `options.random`, a `Function` that returns an `Array` of 16 random bytes (0-255)                                                                                       |
| [`options.seq = (random)`]         | 32-bit sequence `Number` between 0 - 0xffffffff. This may be provided to help ensure uniqueness for UUIDs generated within the same millisecond time interval. Default = random value. |
| [`buffer`]                         | `Uint8Array` or `Uint8Array` subtype (e.g. Node.js `Buffer`). If provided, binary UUID is written into the array, 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:

```javascript
import { v7 as uuidv7 } from "uuid";

uuidv7(); // ⇨ '019d637c-c6fb-74e9-8b9d-2f1d459a4201'
```

### ~~uuid.v8()~~

**_"Intentionally left blank"_**

<!-- prettier-ignore -->
> [!NOTE]
> Version 8 (experimental) UUIDs are "[for experimental or vendor-specific use cases](https://www.rfc-editor.org/rfc/rfc9562.html#name-uuid-version-8)".  The RFC does not define a creation algorithm for them, which is why this package does not offer a `v8()` method.  The `validate()` and `version()` methods do work with such UUIDs, however.

### 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:

```javascript
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.

```javascript
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:

```javascript
import { version as uuidVersion } from "uuid";

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

<!-- prettier-ignore -->
> [!NOTE]
> This method returns `0` for the `NIL` UUID, and `15` for the `MAX` UUID.

## Command Line

UUIDs can be generated from the command line using `uuid`.

```shell
$ 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:

```shell
$ npx uuid --help

Usage:
  uuid
  uuid v1
  uuid v3 <name> <namespace uuid>
  uuid v4
  uuid v5 <name> <namespace uuid>
  uuid v7
  uuid --help

Note: <namespace uuid> may be "URL" or "DNS" to use the corresponding UUIDs
defined by RFC9562
```

## `options` Handling for Timestamp UUIDs

Prior to `uuid@11`, it was possible for `options` state to interfere with the internal state used to ensure uniqueness of timestamp-based UUIDs (the `v1()`, `v6()`, and `v7()` methods). Starting with `uuid@11`, this issue has been addressed by using the presence of the `options` argument as a flag to select between two possible behaviors:

- Without `options`: Internal state is utilized to improve UUID uniqueness.
- With `options`: Internal state is **NOT** used and, instead, appropriate defaults are applied as needed.

## Support

**Browsers**: `uuid` [builds are tested](/uuidjs/uuid/blob/main/wdio.conf.js) against the latest version of desktop Chrome, Safari, Firefox, and Edge. Mobile versions of these same browsers are expected to work but aren't currently tested.

**Node**: `uuid` [builds are tested](https://github.com/uuidjs/uuid/blob/main/.github/workflows/ci.yml#L26-L27) against node ([LTS releases](https://github.com/nodejs/Release)), plus one prior. E.g. At the time of this writing `node@20` is the "maintenance" release and `node@24` is the "current" release, so `uuid` supports `node@20`-`node@24`.

**Typescript**: TS versions released within the past two years are supported. [source](https://github.com/microsoft/TypeScript/issues/49088#issuecomment-2468723715)

## Known issues

<!-- This header is referenced as an anchor in src/rng.ts -->

### "getRandomValues() not supported"

This error occurs in environments where the standard [`crypto.getRandomValues()`](https://developer.mozilla.org/en-US/docs/Web/API/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`](https://github.com/LinusU/react-native-get-random-values#readme)
1. 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:

```javascript
import "react-native-get-random-values";
import { v4 as uuidv4 } from "uuid";
```

---

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