JavaScript UUID: Generate Unique IDs the Right Way

If you’ve ever needed a unique ID in JavaScript, you’ve probably hit this situation:

• You need a stable ID for DOM elements
• You’re generating keys for frontend state
• You want request IDs, session IDs, or client-side identifiers

And then the confusion starts:

Should I use Math.random()?
Should I use Date.now()?
Do I need a library?
What is a UUID actually?

Let’s clear this up practically, the same way developers actually use UUIDs in real projects.

What is a UUID (in simple terms)

A UUID (Universally Unique Identifier) is a 128-bit value designed to be unique across:

• Devices
• Browsers
• Servers
• Time

Example UUID:

550e8400-e29b-41d4-a716-446655440000

It looks random, but it follows a defined structure so collisions are extremely unlikely.

Key point:

UUIDs are not for security — they are for identity.

The mistake most developers make ❌

Many developers start with this:

const id = Math.random().toString(36).slice(2);

const id = Math.random().toString(36).slice(2);

Or this:

const id = Date.now();

const id = Date.now();

These work sometimes, but break in real-world cases:

• Collisions when generated fast
• Same IDs across tabs
• Predictable values
• Problems in distributed systems

If you care about correctness, don’t do this.

The correct way: crypto.randomUUID()

Modern JavaScript already gives you what you need.

Browser support (modern)

const id = crypto.randomUUID();
console.log(id);

const id = crypto.randomUUID();
console.log(id);

Output:

b7f1c4a8-8a1a-4c2e-9b9d-3f7e4f9a6c21

This generates a UUID v4, which is:

• Random
• Collision-resistant
• Fast
• No dependencies

If your environment supports crypto, this should be your default choice.

UUID v4: what you’re actually using

UUIDs come in versions, but you rarely need to memorize them.

The important one for JavaScript developers is:

• UUID v4 → Random-based UUID

Why v4 is preferred:

• No central coordination
• Safe for frontend & backend
• Perfect for client-generated IDs

That’s exactly what crypto.randomUUID() creates.

Node.js UUID generation

Node 16.17+ (built-in)

import { randomUUID } from 'crypto';

const id = randomUUID();

import { randomUUID } from 'crypto';

const id = randomUUID();

No external library needed.

When you do need a library

If you must support:

• Older browsers
• Older Node.js versions

Then use a library only as a fallback.

Example with uuid package:

npm install uuid

npm install uuid

import { v4 as uuidv4 } from 'uuid';

const id = uuidv4();

import { v4 as uuidv4 } from 'uuid';

const id = uuidv4();

Use this only when native crypto is unavailable.

Real-world use cases (where UUIDs actually shine)

1. DOM element IDs

const el = document.createElement('div');
el.id = crypto.randomUUID();

const el = document.createElement('div');
el.id = crypto.randomUUID();

No collisions. No guessing.

2. React keys (when data has no ID)

items.map(item => (
  <Component key={crypto.randomUUID()} />
));

items.map(item => (
  <Component key={crypto.randomUUID()} />
));

⚠️ Use carefully: keys should be stable between renders.

3. Client-side request tracking

const requestId = crypto.randomUUID();
fetch('/api/data', {
  headers: { 'X-Request-ID': requestId }
});

const requestId = crypto.randomUUID();
fetch('/api/data', {
  headers: { 'X-Request-ID': requestId }
});

Helps debugging across frontend & backend.

When NOT to use UUIDs ❌

UUIDs are great — but not everywhere.

Avoid UUIDs when:

• You need sorting by time
• You need short, human-readable IDs
• You’re optimizing database index size

In those cases, consider:

• Auto-increment IDs
• ULID
• NanoID

UUIDs are about uniqueness, not performance tuning.

UUID vs NanoID (quick reality check)

If you want zero thinking, UUID wins.

Common myths about UUIDs

❌ “UUIDs are secure”
✔ They are not encryption.

❌ “UUIDs are slow”
✔ Native crypto UUIDs are fast enough for almost all apps.

❌ “You always need a library”
✔ Modern JS already solved this.

The rule you should follow

If you remember only one thing:

Use crypto.randomUUID() everywhere you can.

• Browser → Yes
• Node.js → Yes
• Library → Only if forced

Simple, reliable, future-proof.

Final takeaway

UUIDs are not fancy — they’re boring and reliable, which is exactly what identifiers should be.

JavaScript already gives you a clean solution.

Use it. Move on. Build things.

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Nasim Khan

I’m Nasim Khan, is a Software Engineer focused on building efficient and user-friendly web applications. SHe writes about web development, programming fundamentals, and modern technologies, sharing practical insights for developers and learners.