# 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?query=workflow%3ABrowser) For the creation of [RFC4122](https://www.ietf.org/rfc/rfc4122.txt) UUIDs - **Complete** - Support for RFC4122 version 1, 3, 4, and 5 UUIDs - **Cross-platform** - Support for ... - CommonJS, [ECMAScript Modules](#ecmascript-modules) and [CDN builds](#cdn-builds) - NodeJS 12+ ([LTS releases](https://github.com/nodejs/Release)) - Chrome, Safari, Firefox, Edge browsers - Webpack and rollup.js module bundlers - [React Native / Expo](#react-native--expo) - **Secure** - Cryptographically-strong random values - **Small** - Zero-dependency, small footprint, plays nice with "tree shaking" packagers - **CLI** - Includes the [`uuid` command line](#command-line) utility > **Note** Upgrading from `uuid@3`? Your code is probably okay, but check out [Upgrading From `uuid@3`](#upgrading-from-uuid3) for details. > **Note** Only interested in creating a version 4 UUID? You might be able to use [`crypto.randomUUID()`](https://developer.mozilla.org/en-US/docs/Web/API/Crypto/randomUUID), eliminating the need to install this library. ## Quickstart To create a random UUID... **1. Install** ```shell npm install uuid ``` **2. Create a UUID** (ES6 module syntax) ```javascript import { v4 as uuidv4 } from 'uuid'; uuidv4(); // ⇨ '9b1deb4d-3b7d-4bad-9bdd-2b0d7b3dcb6d' ``` ... or using CommonJS syntax: ```javascript const { v4: uuidv4 } = require('uuid'); uuidv4(); // ⇨ '1b9d6bcd-bbfd-4b2d-9b5d-ab8dfbbd4bed' ``` 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.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.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.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.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 | Note: Ordering of values in the byte arrays used by `parse()` and `stringify()` follows the left ↠ 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 const bytes = uuidParse('6ec0bd7f-11c0-43da-975e-2a8ad9ebae0b'); // Convert to hex strings to show byte order (for documentation purposes) [...bytes].map((v) => v.toString(16).padStart(2, '0')); // ⇨ // [ // '6e', 'c0', 'bd', '7f', // '11', 'c0', '43', 'da', // '97', '5e', '2a', '8a', // 'd9', 'eb', 'ae', '0b' // ] ``` ### 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 | Note: Ordering of values in the byte arrays used by `parse()` and `stringify()` follows the left ↠ right order of hex-pairs in UUID strings. As shown in the example below. Example: ```javascript import { stringify as uuidStringify } from 'uuid'; const uuidBytes = [ 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` ] | RFC "node" field as an `Array[6]` of byte values (per 4.1.6) | | [`options.clockseq`] | RFC "clock sequence" as a `Number` between 0 - 0x3fff | | [`options.msecs`] | RFC "timestamp" field (`Number` of milliseconds, unix epoch) | | [`options.nsecs`] | RFC "timestamp" field (`Number` of nanoseconds to add to `msecs`, should be 0-10,000) | | [`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`] | `Array \| Buffer` If specified, uuid will be written here in byte-form, 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 | Note: The default [node id](https://tools.ietf.org/html/rfc4122#section-4.1.6) (the last 12 digits in the UUID) is generated once, randomly, on process startup, and then remains unchanged for the duration of the process. Note: `options.random` and `options.rng` are only meaningful on the very first call to `v1()`, where they may be passed to initialize the internal `node` and `clockseq` fields. Example: ```javascript import { v1 as uuidv1 } from 'uuid'; uuidv1(); // ⇨ '2c5ea4c0-4067-11e9-8bad-9b1deb4d3b7d' ``` Example using `options`: ```javascript import { v1 as uuidv1 } from 'uuid'; const v1options = { node: [0x01, 0x23, 0x45, 0x67, 0x89, 0xab], clockseq: 0x1234, msecs: new Date('2011-11-01').getTime(), nsecs: 5678, }; uuidv1(v1options); // ⇨ '710b962e-041c-11e1-9234-0123456789ab' ``` ### uuid.v3(name, namespace[, buffer[, offset]]) Create an RFC version 3 (namespace w/ MD5) UUID API is identical to `v5()`, but uses "v3" instead. ⚠️ Note: 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`] | `Array \| Buffer` If specified, uuid will be written here in byte-form, 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(); // ⇨ '1b9d6bcd-bbfd-4b2d-9b5d-ab8dfbbd4bed' ``` Example using predefined `random` values: ```javascript import { v4 as uuidv4 } from 'uuid'; const v4options = { random: [ 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`] | `Array \| Buffer` If specified, uuid will be written here in byte-form, 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` | 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.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 ``` ## 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 uuid v4 uuid v5 uuid --help Note: may be "URL" or "DNS" to use the corresponding UUIDs defined by RFC4122 ``` ## ECMAScript Modules This library comes with [ECMAScript Modules](https://www.ecma-international.org/ecma-262/6.0/#sec-modules) (ESM) support for Node.js versions that support it ([example](./examples/node-esmodules/)) as well as bundlers like [rollup.js](https://rollupjs.org/guide/en/#tree-shaking) ([example](./examples/browser-rollup/)) and [webpack](https://webpack.js.org/guides/tree-shaking/) ([example](./examples/browser-webpack/)) (targeting both, Node.js and browser environments). ```javascript import { v4 as uuidv4 } from 'uuid'; uuidv4(); // ⇨ '1b9d6bcd-bbfd-4b2d-9b5d-ab8dfbbd4bed' ``` To run the examples you must first create a dist build of this library in the module root: ```shell npm run build ``` ## CDN Builds ### ECMAScript Modules To load this module directly into modern browsers that [support loading ECMAScript Modules](https://caniuse.com/#feat=es6-module) you can make use of [jspm](https://jspm.org/): ```html ``` ### UMD As of `uuid@9` [UMD (Universal Module Definition)](https://github.com/umdjs/umd) builds are no longer shipped with this library. If you need a UMD build of this library, use a bundler like Webpack or Rollup. Alternatively, refer to the documentation of [`uuid@8.3.2`](https://github.com/uuidjs/uuid/blob/v8.3.2/README.md#umd) which was the last version that shipped UMD builds. ## Known issues ### Duplicate UUIDs (Googlebot) This module may generate duplicate UUIDs when run in clients with _deterministic_ random number generators, such as [Googlebot crawlers](https://developers.google.com/search/docs/advanced/crawling/overview-google-crawlers). This can cause problems for apps that expect client-generated UUIDs to always be unique. Developers should be prepared for this and have a strategy for dealing with possible collisions, such as: - Check for duplicate UUIDs, fail gracefully - Disable write operations for Googlebot clients ### "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'; ``` Note: If you are using Expo, you must be using at least `react-native-get-random-values@1.5.0` and `expo@39.0.0`. ### Web Workers / Service Workers (Edge <= 18) [In Edge <= 18, Web Crypto is not supported in Web Workers or Service Workers](https://caniuse.com/#feat=cryptography) and we are not aware of a polyfill (let us know if you find one, please). ### IE 11 (Internet Explorer) Support for IE11 and other legacy browsers has been dropped as of `uuid@9`. If you need to support legacy browsers, you can always transpile the uuid module source yourself (e.g. using [Babel](https://babeljs.io/)). ## Upgrading From `uuid@7` ### Only Named Exports Supported When Using with Node.js ESM `uuid@7` did not come with native ECMAScript Module (ESM) support for Node.js. Importing it in Node.js ESM consequently imported the CommonJS source with a default export. This library now comes with true Node.js ESM support and only provides named exports. Instead of doing: ```javascript import uuid from 'uuid'; uuid.v4(); ``` you will now have to use the named exports: ```javascript import { v4 as uuidv4 } from 'uuid'; uuidv4(); ``` ### Deep Requires No Longer Supported Deep requires like `require('uuid/v4')` [which have been deprecated in `uuid@7`](#deep-requires-now-deprecated) are no longer supported. ## Upgrading From `uuid@3` "_Wait... what happened to `uuid@4` thru `uuid@6`?!?_" In order to avoid confusion with RFC [version 4](#uuidv4options-buffer-offset) and [version 5](#uuidv5name-namespace-buffer-offset) UUIDs, and a possible [version 6](http://gh.peabody.io/uuidv6/), releases 4 thru 6 of this module have been skipped. ### Deep Requires Now Deprecated `uuid@3` encouraged the use of deep requires to minimize the bundle size of browser builds: ```javascript const uuidv4 = require('uuid/v4'); // <== NOW DEPRECATED! uuidv4(); ``` As of `uuid@7` this library now provides ECMAScript modules builds, which allow packagers like Webpack and Rollup to do "tree-shaking" to remove dead code. Instead, use the `import` syntax: ```javascript import { v4 as uuidv4 } from 'uuid'; uuidv4(); ``` ... or for CommonJS: ```javascript const { v4: uuidv4 } = require('uuid'); uuidv4(); ``` ### Default Export Removed `uuid@3` was exporting the Version 4 UUID method as a default export: ```javascript const uuid = require('uuid'); // <== REMOVED! ``` This usage pattern was already discouraged in `uuid@3` and has been removed in `uuid@7`. --- Markdown generated from [README_js.md](README_js.md) by

	Stars	Issues	Version	Updated	Created
cuid	3,339	22	3.0.0	a year ago	12 years ago
nanoid	23,246	6	5.0.7	a month ago	7 years ago
shortid	5,740	16	2.2.16	4 years ago	12 years ago
uniqid	607	25	5.4.0	3 years ago	10 years ago
uuid	14,214	13	9.0.1	8 months ago	13 years ago

cuid vs nanoid vs shortid vs uniqid vs uuid

Downloads in past1 Month3 Months6 Months1 Year2 Years5 YearsAll time

Stats

Popular Searches

Sick of boring JavaScript newsletters?

Downloads in past