[API reference](https://evolu.dev/docs/api-reference) › [@evolu/common](https://evolu.dev/docs/api-reference/common) › [Type](https://evolu.dev/docs/api-reference/common/Type) › instanceOf

```ts
function instanceOf<T>(ctor: T): InstanceOfType<T>;
```

Defined in: [packages/common/src/Type.ts:860](https://github.com/evoluhq/evolu/blob/e7144e2bbe9069362b62dec1b64a8aa922b8f1b0/packages/common/src/Type.ts#L860)

`instanceof` [Type](https://evolu.dev/docs/api-reference/common/Type/interfaces/Type).

Ensures that a value is an instance of the given class constructor.

### Example

```ts
class User {
  constructor(public name: string) {}
}

const UserInstance = instanceOf(User);

const result = UserInstance.from(new User("Alice")); // ok
const error = UserInstance.from({}); // err
```