---
url: /reference/OutputOptions.strict.md
---
# strict

* **Type**: `boolean` | `"auto"`
* **Optional**

Whether to always output `"use strict"` directive in non-ES module outputs.

* `true` - Always emit `"use strict"` at the top of the output (not applicable for ESM format since ESM is always strict).
* `false` - Never emit `"use strict"` in the output.
* `'auto'` - Respect the `"use strict"` directives from the source code.

See [In-depth directive guide](/in-depth/directives) for more details.

## Default

```ts
'auto'
```