Every JavaScript app eventually needs a unique identifier, and the built-in crypto.randomUUID() method makes it a one-liner — no library required. Call it in any modern browser or Node.js environment to get back a random, RFC 4122-compliant UUID as a plain string, ready to use as a database key, session token, or list identifier. Below you'll find copy-paste ready code for generating a UUID in JavaScript, checking whether a string is a well-formed UUID, and the uuid npm package for the versions and environments the native API doesn't cover.
How to Generate a UUID in JavaScript
The simplest way to generate a UUID in JavaScript is crypto.randomUUID(), built into every modern browser (Chrome 92+, Firefox 95+, Safari 15.4+) and Node.js (available globally on Node 19+, or via require('crypto') on Node 14.17+/16.7+) with zero dependencies. After reading a hyphenated string from input, a python uuid walkthrough shows how to turn it back into an object and handle a malformed value with try/except.
const myUuid = crypto.randomUUID();
console.log(myUuid);
// Output: 550e8400-e29b-41d4-a716-446655440000const { randomUUID } = require('crypto');
const myUuid = randomUUID();
console.log(myUuid);
// Output: 550e8400-e29b-41d4-a716-446655440000Explanation
crypto.randomUUID()is available as a global in browsers and on Node.js 19+, so no import is needed in those environments.- On Node.js 14.17+/16.7+, before it became a global,
require('crypto').randomUUID()gives you the exact same function. - It returns a random, RFC 4122 version 4 UUID as a plain 36-character string — not an object — so it drops straight into JSON, URLs, or template literals.
- Under the hood it draws from the platform's cryptographically secure random number generator (the Web Crypto API in browsers, Node's
cryptomodule on the server).
Convert a String to a UUID in JavaScript
JavaScript has no dedicated UUID type — a UUID is just a string — so "converting" one really means validating that a string is well-formed before you trust it. To avoid wasted allocations in a busy screen, reusing one instance instead of creating a new one per call is a tip found in any dart uuid example code for Flutter apps.
function isValidUUID(str) {
const regex = /^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/i;
return regex.test(str);
}
console.log(isValidUUID('550e8400-e29b-41d4-a716-446655440000')); // true
console.log(isValidUUID('not-a-uuid')); // falseimport { validate, version } from 'uuid';
const str = '550e8400-e29b-41d4-a716-446655440000';
console.log(validate(str)); // true
console.log(version(str)); // 4Explanation
- Since a UUID is just a string in JavaScript,
isValidUUID()uses a regex to check the 8-4-4-4-12 hexadecimal pattern. - The
iflag makes the regex case-insensitive, so it matches both uppercase and lowercase hex digits. - The
uuidpackage'svalidate()function checks the same shape but is RFC-aware, andversion()reports which UUID version the string encodes. - Always validate UUIDs coming from user input, URL parameters, or API requests before using them in database queries.
Other Options for Generating UUIDs in JavaScript
crypto.randomUUID() only produces version 4 UUIDs, so reach for the uuid npm package when you need version 1, 5, or 7 identifiers, or support for older browsers and Node.js versions where the native API isn't available.
npm install uuidimport { v4 as uuidv4, v7 as uuidv7 } from 'uuid';
// Version 4 - random, same style as crypto.randomUUID()
const randomId = uuidv4();
// Version 7 - Unix timestamp + random, sortable and index-friendly
const sortableId = uuidv7();Explanation
npm install uuidadds the package to your project; it works in Node.js and in bundled browser code alike.v4()produces the same style of random UUID ascrypto.randomUUID(), useful as a drop-in for environments where the native API isn't available.v7()encodes the current Unix millisecond timestamp in the most significant bits, producing IDs that sort chronologically — ideal for database primary keys.- The package also exports
v1()(timestamp + node ID) andv5()/v3()(deterministic, namespace-based) for casescrypto.randomUUID()can't cover.