# throttle

> Wrap a callback so it fires at most every `waitMs`, honouring both the leading and trailing edge. Returns a function with a `.cancel()` method for safe teardown.

Source: https://ngwr.dev/reference/utils/throttle  
Kind: Util

## Usage

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

const onScroll = throttle(() => trackScroll(), 100);
window.addEventListener('scroll', onScroll);

onScroll.cancel();   // teardown
```

## Why ngwr provides this

Hand-rolled throttles almost always forget the trailing edge — so the final scroll position / drag coordinate is silently dropped. ngwr's version handles both edges and exposes `.cancel()` so component teardown stays clean.

```angular-ts
// Native — most hand-rolled throttles forget the trailing edge.
let lastRun = 0;
function onScroll() {
  const now = Date.now();
  if (now - lastRun >= 100) {
    lastRun = now;
    trackScroll();
  }
}
// → final scroll position is never reported (no trailing call).

// ngwr — leading + trailing edge, with `.cancel()` for teardown.
const onScroll = throttle(() => trackScroll(), 100);
destroyRef.onDestroy(() => onScroll.cancel());
```

## API

| Name | Description | Type | Default |
| --- | --- | --- | --- |
| `throttle(fn, waitMs)` | Returns a wrapper that fires `fn` at most every `waitMs` (leading and trailing edge). Exposes `.cancel()` for teardown. | `(fn, ms) => WrThrottledFn` | `—` |