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) 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 --run v1
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
```javascript --run v1
// Generate two ids in an array
const arr = new Array();
uuidv1(null, arr, 0); // RESULT
uuidv1(null, arr, 16); // RESULT
```
### Version 3
```javascript
const uuidv3 = require('uuid/v3');
// Incantations
uuidv3(name, namespace);
uuidv3(name, namespace, buffer);
uuidv3(name, namespace, buffer, offset);
```
Generate and return a RFC4122 v3 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 --run v3
uuidv3('hello world', MY_NAMESPACE); // RESULT
```
### Version 4
```javascript
const uuidv4 = require('uuid/v4')
// Incantations
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 predefined `random` values
```javascript --run v4
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
```javascript --run v4
const buffer = new Array();
uuidv4(null, buffer, 0); // RESULT
uuidv4(null, buffer, 16); // RESULT
```
### Version 5
```javascript
const uuidv5 = require('uuid/v5');
// Incantations
uuidv5(name, namespace);
uuidv5(name, namespace, buffer);
uuidv5(name, namespace, buffer, offset);
```
Generate and return a RFC4122 v5 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 --run v5
uuidv5('hello world', MY_NAMESPACE); // RESULT
```
## Command Line
UUIDs can be generated from the command line with the `uuid` command.
