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

```ts
const assertTrue: (value: unknown) => asserts value is true;
```

Defined in: [packages/common/src/Assert.ts:98](https://github.com/evoluhq/evolu/blob/037c390af081e9944d616ff298a729515c5c5ab7/packages/common/src/Assert.ts#L98)

Asserts that a value is exactly `true` and narrows it to `true`.

Unlike [assert](https://evolu.dev/docs/api-reference/common/Assert/variables/assert), this checks an exact boolean value instead of
truthiness and does not require a custom message.

### Example

```ts

const value: unknown = true;
assertTrue(value);
assertType<true, typeof value>();
```