Generate UUID in JavaScript: crypto.randomUUID() Guide

How to Generate UUIDs in JavaScript

Since 2021, modern browsers and Node.js 19+ include crypto.randomUUID() — a native, cryptographically secure UUID v4 generator that requires no external dependencies. For older environments, the uuid npm package remains the standard choice with over 100 million weekly downloads.

Native: crypto.randomUUID()

// Browser (Chrome 92+, Firefox 95+, Safari 15.4+)
const id = crypto.randomUUID();
console.log(id); // \"3b241101-e2bb-4d52-8376-9e5c8e1f3a41\"

// Node.js 19+
const { randomUUID } = require(\"crypto\");
console.log(randomUUID()); // Same format

// Generate multiple UUIDs
const ids = Array.from({ length: 10 }, () => crypto.randomUUID());
console.log(ids);

npm uuid Package

// Install: npm install uuid
const { v4: uuidv4 } = require(\"uuid\");

const id = uuidv4();
console.log(id); // \"9b1deb4d-3b7d-4bad-9bdd-2b0d7b3dcb6d\"

// Validate a UUID
const { validate } = require(\"uuid\");
console.log(validate(\"not-a-uuid\")); // false
console.log(validate(id));            // true

// Detect UUID version
const { version } = require(\"uuid\");
console.log(version(id)); // 4

Manual Implementation (No Dependencies)

If you cannot use crypto.randomUUID() and do not want a dependency, here is a minimal implementation using crypto.getRandomValues():

function generateUUID() {
    const bytes = new Uint8Array(16);
    crypto.getRandomValues(bytes);
    // Set version 4 (0100) in byte 6
    bytes[6] = (bytes[6] & 0x0f) | 0x40;
    // Set variant 1 (10xx) in byte 8
    bytes[8] = (bytes[8] & 0x3f) | 0x80;
    const hex = [...bytes].map(b => b.toString(16).padStart(2, \"0\"));
    return [
        hex.slice(0, 4).join(\"\"),
        hex.slice(4, 6).join(\"\"),
        hex.slice(6, 8).join(\"\"),
        hex.slice(8, 10).join(\"\"),
        hex.slice(10, 16).join(\"\")
    ].join(\"-\");
}

When to Use UUIDs in JavaScript

• Database primary keys — generate IDs client-side before inserting, enabling offline-first apps and optimistic UI updates
• Temporary IDs — assign unique IDs to DOM elements, form fields, or component instances
• Idempotency keys — prevent duplicate API submissions by attaching a UUID to each request
• Session identifiers — track anonymous users or browser sessions without cookies
• File naming — generate unique filenames for uploads to prevent collisions in cloud storage

Browser Support

crypto.randomUUID() is supported in Chrome 92+, Edge 92+, Firefox 95+, Safari 15.4+, and Node.js 19+. For older browsers, use the uuid package or the manual implementation above. Always check typeof crypto.randomUUID === \"function\" before using the native method.