---
source: crates/biome_js_analyze/tests/spec_tests.rs
expression: invalid.ts
---
# Input
```ts
export { foo, type Bar } from "foo";
```

# Diagnostics
```
invalid.ts:1:1 lint/nursery/noBarrelFile ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! Avoid barrel files, they slow down performance, and cause large module graphs with modules that go unused.
  
  > 1 │ export { foo, type Bar } from "foo";
      │ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  
  i Check this thorough explanation to better understand the context.
  

```