# uuid [](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.
