---
title: lambda/*.[tj]s
sidebar_position: 3
---
# lambda/*.[tj]s

After enabling BFF, the files under the `lambda/` directory will be registered as BFF routes according to conventions.

:::note
The files can be written in `js` or `ts` languages, but they must use `esm` syntax to export functions.
:::

For detailed information, refer to [BFF API Routes](/guides/advanced-features/bff/function.html#api-routes).