# Function: useSource()

> **useSource**\<`T`\>(`type`): `SourceFn`\<`T`\>

Creates a source whose identity remains stable while the component is mounted.

Use [`source`](/api/rxjs/index/source-1) to create a source outside a component.

The returned `SourceFn` is both a callable event emitter and an RxJS
Subject. An optional `type` labels its emissions in Redux DevTools.

```tsx
import { useAdapt, useSource } from '@state-adapt/react';

function Counter() {
  const onSet = useSource<number>('set');
  const [count] = useAdapt(0, { sources: onSet });

  return <button onClick={() => onSet(1)}>{count.state}</button>;
}
```