uuid

What is uuid?

The uuid npm package is used to generate universally unique identifiers (UUIDs), which are 128-bit numbers used to uniquely identify information in computer systems. The package supports multiple versions of UUIDs, each with different methods of generation based on requirements such as randomness, time-based generation, and name-based generation using namespaces.

What are uuid's main functionalities?

Generate UUID v1

Generates a version 1 UUID based on timestamp and MAC address of the host machine, ensuring temporal uniqueness.

const { v1: uuidv1 } = require('uuid');
console.log(uuidv1());

Generate UUID v4

Generates a version 4 UUID using random or pseudo-random numbers, providing a higher degree of randomness.

const { v4: uuidv4 } = require('uuid');
console.log(uuidv4());

Generate UUID v3

Generates a version 3 UUID using MD5 hashing of a namespace identifier and a name.

const { v3: uuidv3 } = require('uuid');
const MY_NAMESPACE = '1b671a64-40d5-491e-99b0-da01ff1f3341';
console.log(uuidv3('Hello, World!', MY_NAMESPACE));

Generate UUID v5

Generates a version 5 UUID using SHA-1 hashing of a namespace identifier and a name, providing better uniqueness and lower collision probability than v3.

const { v5: uuidv5 } = require('uuid');
const MY_NAMESPACE = '1b671a64-40d5-491e-99b0-da01ff1f3341';
console.log(uuidv5('Hello, World!', MY_NAMESPACE));

Other packages similar to uuid

shortid

ShortId generates short, non-sequential, URL-friendly unique ids. Unlike uuid, which generates 128-bit long UUIDs, ShortId creates shorter ids, which can be easier to use in URLs or when space is limited. However, ShortId is not recommended for security-critical applications due to the shorter identifier length and lower entropy.

nanoid

NanoId is a tiny, secure, URL-friendly, unique string ID generator for JavaScript. It is similar to uuid v4 in that it provides a way to generate random IDs, but it offers a customizable alphabet and length, allowing for a wider range of possible IDs. NanoId claims to be faster and more compact than UUID, making it a good alternative for many applications.

cuid

CUID (Collision-resistant Unique Identifier) is another alternative for generating unique identifiers. It is designed to be more collision-resistant than uuid and is optimized for horizontal scaling and sequential lookup performance. CUIDs are longer than UUIDs and contain a timestamp, which can be useful for sorting records in a database.

README

uuid

Simple, fast generation of RFC4122 UUIDS.

Features:

• Generate RFC4122 version 1 or version 4 UUIDs
• Runs in node.js and all browsers.
• Cryptographically strong random # generation on supporting platforms
• 1185 bytes minified and gzip'ed (Want something smaller? Check this crazy shit out! )
• Annotated source code

Getting Started

Install it in your browser:

<script src="uuid.js"></script>

Or in node.js:

npm install uuid

var uuid = require('uuid');

// Generate a v1 (time-based) id
uuid.v1(); // -> '6c84fb90-12c4-11e1-840d-7b25c5ee775a'

// Generate a v4 (random) id
uuid.v4(); // -> '110ec58a-a0f2-4ac4-8393-c866d813b8d1'

API

uuid.v1([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

Notes:

1. The randomly generated node id is only 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

uuid.v1({
  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

// Generate two ids in an array
var arr = new Array(32); // -> []
uuid.v1(null, arr, 0);   // -> [02 a2 ce 90 14 32 11 e1 85 58 0b 48 8e 4f c1 15]
uuid.v1(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]

// Optionally use uuid.unparse() to get stringify the ids
uuid.unparse(buffer);    // -> '02a2ce90-1432-11e1-8558-0b488e4fc115'
uuid.unparse(buffer, 16) // -> '02a31cb0-1432-11e1-8558-0b488e4fc115'

uuid.v4([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 to use. Set to one of the built-in generators - uuid.mathRNG (all platforms), uuid.nodeRNG (node.js only), uuid.whatwgRNG (WebKit only) - or a custom function that returns an 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.

Returns buffer, if specified, otherwise the string form of the UUID

Example: Generate string UUID with fully-specified options

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

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

uuid.parse(id[, buffer[, offset]])

uuid.unparse(buffer[, offset])

Parse and unparse UUIDs

• id - (String) UUID(-like) string
• buffer - (Array | Buffer) Array or buffer where UUID bytes are to be written. Default: A new Array or Buffer is used
• offset - (Number) Starting index in buffer at which to begin writing. Default: 0

Example parsing and unparsing a UUID string

var bytes = uuid.parse('797ff043-11eb-11e1-80d6-510998755d10'); // -> <Buffer 79 7f f0 43 11 eb 11 e1 80 d6 51 09 98 75 5d 10>
var string = uuid.unparse(bytes); // -> '797ff043-11eb-11e1-80d6-510998755d10'

uuid.noConflict()

(Browsers only) Set uuid property back to it's previous value.

Returns the uuid object.

Example:

var myUuid = uuid.noConflict();
myUuid.v1(); // -> '6c84fb90-12c4-11e1-840d-7b25c5ee775a'

Deprecated APIs

Support for the following v1.2 APIs is available in v1.3, but is deprecated and will be removed in the next major version.

uuid([format [, buffer [, offset]]])

uuid() has become uuid.v4(), and the format argument is now implicit in the buffer argument. (i.e. if you specify a buffer, the format is assumed to be binary).

Testing

In node.js

> cd test
> node test.js

In Browser

open test/test.html

Benchmarking

Requires node.js

cd benchmark/
npm install
node benchmark.js

For a more complete discussion of uuid performance, please see the benchmark/README.md file, and the benchmark wiki

For browser performance checkout the JSPerf tests.

Release notes

2.0.0

• Removed uuid.BufferClass

1.4.0

• Improved module context detection
• Removed public RNG functions

1.3.2

• Improve tests and handling of v1() options (Issue #24)
• Expose RNG option to allow for perf testing with different generators

1.3.0

• Support for version 1 ids, thanks to @ctavan!
• Support for node.js crypto API
• De-emphasizing performance in favor of a) cryptographic quality PRNGs where available and b) more manageable code