# useMounted

Returns `true` after the component has mounted on the client. Useful for deferring client-only rendering to avoid SSR hydration mismatches.

## Signature

```ts
function useMounted(): boolean;
```

## Usage

```tsx
function ThemeToggle() {
  const mounted = useMounted();

  if (!mounted) return null; // avoid SSR/hydration mismatch

  return <button>{getCurrentTheme()}</button>;
}
```

## Notes

- Always returns `false` on the first render (SSR and initial client render), then `true` after `useEffect` fires.
- Client-only (`'use client'`).