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# uuid [![Build Status](https://secure.travis-ci.org/kelektiv/node-uuid.svg?branch=master)](http://travis-ci.org/kelektiv/node-uuid) #

Simple, fast generation of [RFC4122](http://www.ietf.org/rfc/rfc4122.txt) UUIDS.

Features:

* Support for version 1, 4 and 5 UUIDs
* Cross-platform
* Uses cryptographically-strong random number APIs (when available)
* Zero-dependency, small footprint (... but not [this small](https://gist.github.com/982883))

## Quickstart - CommonJS (Recommended)

```shell
npm install uuid
```

Then generate your uuid version of choice ...

Version 1 (timestamp):

```javascript
const uuidv1 = require('uuid/v1');
uuidv1(); // -> '6c84fb90-12c4-11e1-840d-7b25c5ee775a'
```

Version 4 (random):

```javascript
const uuidv4 = require('uuid/v4');
uuidv4(); // -> '110ec58a-a0f2-4ac4-8393-c866d813b8d1'
```

Version 5 (namespace):

```javascript
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
const MY_NAMESPACE = '<UUID string you previously generated elsewhere>';
uuidv5('Hello, World!', MY_NAMESPACE); // -> '90123e1c-7512-523e-bb28-76fab9f2f73d'
```

## Quickstart - Browser-ready Versions

Browser-ready versions of this module are available via [wzrd.in](https://github.com/jfhbrook/wzrd.in).

For version 1 uuids:

```html
<script src="http://wzrd.in/standalone/uuid%2Fv1@latest"></script>
<script>
uuidv1(); // -> v1 UUID
</script>
```

For version 4 uuids:

```html
<script src="http://wzrd.in/standalone/uuid%2Fv4@latest"></script>
<script>
uuidv4(); // -> v4 UUID
</script>
```

For version 5 uuids:

```html
<script src="http://wzrd.in/standalone/uuid%2Fv5@latest"></script>
<script>
uuidv5('http://example.com/hello', uuidv5.URL); // -> v5 UUID
</script>
```

## API

### Version 1

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

// Allowed arguments
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 | Date) 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 <node> id is generated guaranteed to stay constant for the lifetime of the current JS runtime. (Future versions of this module may use persistent storage mechanisms to extend this guarantee.)

Example: Generate string UUID with fully-specified options

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

Example: In-place generation of two binary IDs

```javascript
// Generate two ids in an array
const arr = new Array(32); // -> []
uuidv1(null, arr, 0);   // -> [02 a2 ce 90 14 32 11 e1 85 58 0b 48 8e 4f c1 15]
uuidv1(null, arr, 16);  // -> [02 a2 ce 90 14 32 11 e1 85 58 0b 48 8e 4f c1 15 02 a3 1c b0 14 32 11 e1 85 58 0b 48 8e 4f c1 15]
```

### Version 4

```javascript
const uuidv4 = require('uuid/v4')

// Allowed arguments
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 fully-specified options

```javascript
uuid.v4({
  random: [
    0x10, 0x91, 0x56, 0xbe, 0xc4, 0xfb, 0xc1, 0xea,
    0x71, 0xb4, 0xef, 0xe1, 0x67, 0x1c, 0x58, 0x36
  ]
});
// -> "109156be-c4fb-41ea-b1b4-efe1671c5836"
```

Example: Generate two IDs in a single buffer

```javascript
const buffer = new Array(32); // (or 'new Buffer' in node.js)
uuid.v4(null, buffer, 0);
uuid.v4(null, buffer, 16);
```

### Version 5

```javascript
const uuidv5 = require('uuid/v4');

// Allowed arguments
uuidv5(name, namespace);
uuidv5(name, namespace, buffer);
uuidv5(name, namespace, buffer, offset);
```

Generate and return a RFC4122 v4 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:

```javascript
// Generate a unique  namespace (typically you would do this once, outside of
// your project, then bake this value into your code)
const uuidv4 = require('uuid/v4');
const MY_NAMESPACE = uuidv4();  //

// Generate a couple namespace uuids
const uuidv5 = require('uuid/v5');
uuidv5('hello', MY_NAMESPACE);
uuidv5('world', MY_NAMESPACE);
```

## Testing

```shell
npm test
```

## Deprecated / Browser-ready API

The API below is available for legacy purposes and is not expected to be available post-3.X

```javascript
const uuid = require('uuid');

uuid.v1(...); // alias of uuid/v1
uuid.v4(...); // alias of uuid/v4
uuid(...);    // alias of uuid/v4

// uuid.v5() is not supported in this API
```

## Legacy node-uuid package

The code for the legacy node-uuid package is available in the `node-uuid` branch.