# uuid [](https://github.com/uuidjs/uuid/actions) For the creation of [RFC4122](http://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 UMD builds - Node 8, 10, 12 - Chrome, Safari, Firefox, Edge, IE 11 browsers - Webpack and rollup.js module bundlers - [React Native](#react-native) - **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 **Upgrading from uuid\@3?** Your code is probably okay, but check out [Upgrading From uuid\@3](#upgrading-from-uuid3) for details. ## Quickstart - Node.js/CommonJS ```shell npm install uuid ``` Once installed, decide which type of UUID you need. RFC4122 provides for four versions, all of which are supported here. In order of popularity, they are: - Version 4 (random) - Created from cryptographically-strong random values - Version 1 (timestamp) - Created from the system clock (plus random values) - Version 5 (namespace, SHA-1) - Created from user-supplied name and namespace strings - Version 3 (namespace, MD5) - Like version 5, above, but with a poorer hash algorithm **Unsure which one to use?** Use version 4 (random) unless you have a specific need for one of the other versions. See also [this FAQ](https://github.com/tc39/proposal-uuid#faq). ### Create Version 4 (Random) UUIDs ```javascript import { v4 as uuidv4 } from 'uuid'; uuidv4(); // ⇨ '9b1deb4d-3b7d-4bad-9bdd-2b0d7b3dcb6d' ``` ### Create Version 1 (Timestamp) UUIDs ```javascript import { v1 as uuidv1 } from 'uuid'; uuidv1(); // ⇨ '2c5ea4c0-4067-11e9-8b2d-1b9d6bcdbbfd' ``` ### Create Version 3 or Version 5 (Namespace) UUIDs ⚠️ Version 3 and Version 5 UUIDs are basically the same, differing only in the underlying hash algorithm. Note that per the RFC, "_If backward compatibility is not an issue, SHA-1 [Version 5] is preferred_." ⚠️ If using a custom namespace **be sure to generate your own namespace UUID**. You can grab one [here](https://www.uuidgenerator.net/). ```javascript import { v5 as uuidv5 } from 'uuid'; // For version 5 import { v3 as uuidv3 } from 'uuid'; // For version 3 // Using predefined DNS namespace (for domain names) uuidv5('hello.example.com', uuidv5.DNS); // ⇨ 'fdda765f-fc57-5604-a269-52a7df8164ec' uuidv3('hello.example.com', uuidv3.DNS); // ⇨ '9125a8dc-52ee-365b-a5aa-81b0b3681cf6' // Using predefined URL namespace (for URLs) uuidv5('http://example.com/hello', uuidv5.URL); // ⇨ '3bbcee75-cecc-5b56-8031-b6641c1ed1f1' uuidv3('http://example.com/hello', uuidv3.URL); // ⇨ 'c6235813-3ba4-3801-ae84-e0a6ebb7d138' // Using a custom namespace (See note, above, about generating your own // namespace UUID) const MY_NAMESPACE = '1b671a64-40d5-491e-99b0-da01ff1f3341'; uuidv5('Hello, World!', MY_NAMESPACE); // ⇨ '630eb68f-e0fa-5ecc-887a-7c7a62614681' uuidv3('Hello, World!', MY_NAMESPACE); // ⇨ 'e8b5a51d-11c8-3310-a6ab-367563f20686' ``` ## API ### Version 4 (Random) ```javascript import { v4 as uuidv4 } from 'uuid'; // Incantations uuidv4(); uuidv4(options); uuidv4(options, buffer, offset); ``` Generate and return a RFC4122 version 4 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. Takes precedence over `options.rng`. - `rng` - (Function) Random # generator function that returns an Array[16] of byte values (0-255). Alternative to `options.random`. - `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 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' ``` Example: Generate two IDs in a single buffer ```javascript const buffer = new Array(); uuidv4(null, buffer, 0); // ⇨ // [ // 155, 29, 235, 77, 59, // 125, 75, 173, 155, 221, // 43, 13, 123, 61, 203, // 109 // ] uuidv4(null, buffer, 16); // ⇨ // [ // 155, 29, 235, 77, 59, 125, 75, 173, // 155, 221, 43, 13, 123, 61, 203, 109, // 27, 157, 107, 205, 187, 253, 75, 45, // 155, 93, 171, 141, 251, 189, 75, 237 // ] ``` ### Version 1 (Timestamp) ```javascript import { v1 as uuidv1 } from 'uuid'; // Incantations uuidv1(); uuidv1(options); uuidv1(options, buffer, offset); ``` Generate and return a RFC4122 version 1 (timestamp) 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. - `random` - (Number[16]) Array of 16 numbers (0-255) to use for initialization of `node` and `clockseq` as described above. Takes precedence over `options.rng`. - `rng` - (Function) Random # generator function that returns an Array[16] of byte values (0-255). Alternative to `options.random`. - `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 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. Example: Generate string UUID with fully-specified options ```javascript 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' ``` Example: In-place generation of two binary IDs ```javascript // Generate two ids in an array const arr = new Array(); uuidv1(null, arr, 0); // ⇨ // [ // 44, 94, 164, 192, 64, // 103, 17, 233, 146, 52, // 27, 157, 107, 205, 187, // 253 // ] uuidv1(null, arr, 16); // ⇨ // [ // 44, 94, 164, 192, 64, 103, 17, 233, // 146, 52, 27, 157, 107, 205, 187, 253, // 44, 94, 164, 193, 64, 103, 17, 233, // 146, 52, 27, 157, 107, 205, 187, 253 // ] ``` ### Version 5 (Namespace) ```javascript import { v5 as uuidv5 } from 'uuid'; // Incantations uuidv5(name, namespace); uuidv5(name, namespace, buffer); uuidv5(name, namespace, buffer, offset); ``` Generate and return a RFC4122 version 5 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 uuidv5('hello world', MY_NAMESPACE); // ⇨ '9f282611-e0fd-5650-8953-89c8e342da0b' ``` ### Version 3 (Namespace) ⚠️ Note: Per the RFC, "_If backward compatibility is not an issue, SHA-1 [Version 5] is preferred_." ```javascript import { v3 as uuidv3 } from 'uuid'; // Incantations uuidv3(name, namespace); uuidv3(name, namespace, buffer); uuidv3(name, namespace, buffer, offset); ``` Generate and return a RFC4122 version 3 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 uuidv3('hello world', MY_NAMESPACE); // ⇨ '042ffd34-d989-321c-ad06-f60826172424' ``` ## Command Line UUIDs can be generated from the command line using `uuid`. ```shell $ 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: ``` $ 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 For usage in the browser `uuid` provides support for [ECMAScript Modules](https://www.ecma-international.org/ecma-262/6.0/#sec-modules) (ESM) that enable tree-shaking for 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/)). ```javascript import { v4 as uuidv4 } from 'uuid'; uuidv4(); // ⇨ '1b9d6bcd-bbfd-4b2d-9b5d-ab8dfbbd4bed' ``` There is experimental native ESM support for [the browser](./examples/browser-esmodules/) but it should not be considered ready for production use and may change or disappear in future releases. To run the examples you must first create a dist build of this library in the module root: ``` npm run build ``` ## UMD Builds If you want to load a minified UMD build directly in the browser you can use one of the popular npm CDNs: ```html ``` or ```html ``` Available bundles: - https://unpkg.com/uuid@latest/dist/umd/ - https://cdn.jsdelivr.net/npm/uuid@latest/dist/umd/ ## "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 1. Install [`react-native-get-random-values`](https://github.com/LinusU/react-native-get-random-values#readme) 1. Import it before `uuid`: ```javascript import 'react-native-get-random-values'; import { v4 as uuidv4 } from 'uuid'; ``` ### 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). ## Upgrading From uuid\@3 "_Wait... what happened to uuid\@4 - uuid\@6?!?_" In order to avoid confusion with RFC [version 4](#version-4-random) and [version 5](#version-5-namespace) UUIDs, and a possible [version 6](http://gh.peabody.io/uuidv6/), releases 4 thru 6 of this module have been skipped. Hence, how we're now at uuid\@7. ### 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 [](https://github.com/broofa/runmd)