# randomId

> Stable, short random identifier — use for `<label for>` / `aria-describedby` pairings inside components.

Source: https://ngwr.dev/reference/utils/random-id  
Kind: Util

## Usage

```angular-ts
import { randomId } from 'ngwr/utils';

const id = randomId('wr-input');     // 'wr-input-a8f2bx1k9q4z'  (12 chars)
const short = randomId('wr-input', 6); // 'wr-input-h7m4k2'
```

## Why ngwr provides this

Every component that pairs a label with a control (`<label for>`, `aria-describedby`, `aria-controls`) needs a stable unique id per instance. Each native option is unsatisfying: `Math.random()` collides under load, `Date.now()` collides on the same tick, `crypto.randomUUID()` is 36 chars and isn't in every SSR runtime. `randomId` is short, prefixed, and SSR-safe.

```angular-ts
// Native options all have downsides:
const a = Math.random().toString(36).slice(2);   // collides under load, no prefix
const b = `id-${Date.now()}`;                    // collides when called twice the same tick
const c = crypto.randomUUID();                   // 36 chars, ugly in HTML, not in every SSR runtime

// ngwr — short, prefixed, collision-resistant, SSR-safe.
const id = randomId('wr-input');   // 'wr-input-a8f2bx1k9q4z'
```

## API

| Name | Description | Type | Default |
| --- | --- | --- | --- |
| `randomId(prefix?, length?, random?)` | Generates a stable random id like `wr-input-a8f2bx1k9q4z`. Safe for SSR (uses crypto when available). `length` is the random segment only, clamped to `[4, 64]`; `random` replaces the byte source, which is what makes an id deterministic in a test. | `(prefix = 'wr', length = 12, random?: (byteLength: number) => Uint8Array) => string` | `—` |